Thyroidtests

Some information on this page is a little more advanced.
If you have trouble understanding the process of normal thyroid function, please go to our page describing this process first.

As you will seen in your overview of normal thyroid physiology, the thyroid gland produces T4 (also called thyroxine) and T3. But this production is not possible without stimulation from the pituitary gland (TSH) which in turn is also regulated by the hypothalamus's TSH Releasing Hormone (TRH). Now, with modern immunoassay techniques it is possible to measure circulating hormones in the blood very accurately. Knowledge of this thyroid physiology is important in knowing what thyroid test or tests are needed to diagnose different diseases. No one single laboratory test is 100% accurate in diagnosing all types of thyroid disease; however, a combination of two or more tests can usually detect even the slightest abnormality of thyroid function.

For example, a low T4 level could mean a diseased thyroid gland or a non-functioning pituitary gland which is not stimulating the thyroid to produce T4. Since the pituitary gland would normally release TSH if the T4 is low, a high TSH level would confirm that the thyroid gland (not the pituitary gland) is responsible for the hypothyroidism, a condition sometimes called primary hypothyroidism.

If the T4 level is low and TSH is not elevated, the pituitary gland is more likely to be the cause for the hypothyroidism. Of course, this would drastically effect the treatment since the pituitary gland also regulates the body's other glands (adrenals, ovaries, and testicles) as well as controlling growth in children and normal kidney function. Pituitary gland failure means that the other glands may also be failing and other treatment than just thyroid may be necessary. The most common cause for the pituitary gland failure is a tumor of the pituitary and this might also require surgery to remove.

Measurement of Serum Thyroid Hormones: T4 by immunoassay. Measurement of thyroxine (T4) by modern immunoassay is the most used thyroid test of all. Nearly all of the T4 circulating in the serum is bound to a protein called thryroxine binding globulin (TBG) and is not physiologically active so tests that measure all the T4 in serum really measure the total T4 level. Because of this TBG binding, a elevation or decrease in serum T4 may be due to change in TBG level and not reflect clinical hyperthyroidism or hypothyroidism. Since only the free or non-TBG bound T4 results in clinical changes in the patient, it is best to measure the Free-T4 rather than the total T4.

Measurement of Serum Thyroid Hormones: T3 by immunoassay. Thyroxine (T4) represents 80% of the thyroid hormone produced by the normal gland and generally represents the overall function of the gland. The other 20% is triiodothyronine measured as T3 by immunoassay. Sometimes the diseased thyroid gland will start producing very high levels of T3 but still produce normal levels of T4. Therefore measurement of both hormones provides an even more accurate evaluation of thyroid function.

Thyroid Binding Globulin. Most of the thyroid hormones in the blood are attached to a protein called thyroid binding globulin (TBG). If there is an excess or deficiency of this protein it alters thetotal T4 or T3 measurement but does not affect the action of the hormone since the Free T4 should remain normal. If a patient appears to have normal thyroid function, but an unexplained high or low T4, or T3, it may be due to an increase or decrease of TBG. Direct measurement of TBG can be done and will explain the abnormal value. Excess TBG or low levels of TBG are found in some families as an hereditary trait. It causes no problem except falsely elevating or lowering the T4 level. These people are frequently misdiagnosed as being hyperthyroid or hypothyroid, but they have no thyroid problem and need no treatment.

Measurement of Pituitary Production of TSH. Pituitary production of TSH is measured by third generation high sensitivity methodology that can measure extremely low levels of TSH in the serum or plasma. Normal TSH levels are sufficient to keep the normal thyroid gland functioning properly. When the thyroid gland becomes inefficient such as in early hypothyroidism, the TSH becomes elevated even though the T4 and T3 may still be within the "normal" range. This rise in TSH represents the pituitary gland's response to a drop in circulating thyroid hormone; it is usually the first indication of thyroid gland failure. Since TSH is normally low when the thyroid gland is functioning properly, the failure of TSH to rise when circulating thyroid hormones are low is an indication of impaired pituitary function. The new "highly sensitive" TSH test will show very low levels (below normal levels) of TSH when the thyroid is overactive (as a normal response of the pituitary to try to decrease thyroid stimulation). Interpretations of the TSH level depends upon the level of thyroid hormone; therefore, the TSH is usually used in combination with other thyroid tests such as the T4, Free T4 and T3 immunoassays.

TRH Test. In normal people TSH secretion from the pituitary can be increased by giving a shot containing TSH Releasing Hormone (TRH...the hormone released by the hypothalamus which tells the pituitary to produce TSH). A baseline TSH of 5 or less usually goes up to 10-20 after giving an injection of TRH. Patients with too much thyroid hormone (thyroxine or triiodothyronine) will not show a rise in TSH when given TRH. This "TRH test" is presently the most sensitive test in detecting early hyperthyroidism. Patients who show too much response to TRH (TSH rises greater than 40) may be hypothyroid. This test is also used in cancer patients who are taking thyroid replacement to see if they are on sufficient medication. It is sometimes used to measure if the pituitary gland is functioning. The new "highly sensitive" TSH test (above) has eliminated the necessity of performing a TRH test in most clinical situations.

Iodine Uptake Scan. A means of measuring thyroid function is to measure how much iodine is taken up by the thyroid gland (RAI uptake). Remember, cells of the thyroid normally absorb iodine from our blood stream (obtained from foods we eat) and use it to make thyroid hormone (described on our thyroid function page). Hypothyroid patients usually take up too little iodine and hyperthyroid patients take up too much iodine. The test is performed by giving a dose of radioactive iodine on an empty stomach. The iodine is concentrated in the thyroid gland or excreted in the urine over the next few hours. The amount of iodine that goes into the thyroid gland can be measured by a "Thyroid Uptake". Of course, patients who are taking thyroid medication will not take up as much iodine in their thyroid gland because their own thyroid gland is turned off and is not functioning. At other times the gland will concentrate iodine normally but will be unable to convert the iodine into thyroid hormone; therefore, interpretation of the iodine uptake is usually done in conjunction with blood tests.

Cold nodule.

Thyroid Scan. Taking a "picture" of how well the thyroid gland is functioning requires giving a radioisotope to the patient and letting the thyroid gland concentrate the isotope (just like the iodine uptake scan above). Therefore, it is usually done at the same time that the iodine uptake test is performed. Although other isotopes, such as technetium, will be concentrated by the thyroid gland; these isotopes will not measure iodine uptake which is what we really want to know because the production of thyroid hormone is dependent upon absorbing iodine. It has also been found that thyroid nodules that concentrate iodine are rarely cancerous; this is not true if the scan is done with technetium. Therefore, all scans are now done with radioactive iodine. Both of the scans above show normal sized thyroid glands, but the one on the left has a "HOT" nodule in the lower aspect of the right lobe, while the scan on the right has a "COLD" nodule in the lower aspect of the left lobe (outlined in red and yellow). Pregnant women should not have thyroid scans performed because the iodine can cause development troubles within the baby's thyroid gland. A normal CRT thyroid scan.

Identifying nodules and determining if they are "hot" or "cold".

Measuring the size of the goiter prior to treatment.

Follow-up of thyroid cancer patients after surgery.

Locating thyroid tissue outside the neck, i.e. base of the tongue or in the chest.

Thyroid Ultrasound. Thyroid ultrasound refers to the use of high frequency sound waves to obtain an image of the thyroid gland and identify nodules. It tells if a nodule is "solid" or a fluid-filled cyst, but it will not tell if a nodule is benign or malignant. Ultrasound allows accurate measurement of a nodule's size and can determine if a nodule is getting smaller or is growing larger during treatment. Ultrasound aids in performing thyroid needle biopsy by improving accuracy if the nodule cannot be felt easily on examination. Several more pages are dedicated to the use of ultrasound in evaluating thyroid nodules.

Thyroid Antibodies. The body normally produces antibodies to foreign substances; however, some people are found to have antibodies against their own thyroid tissue. A condition known as Hashimoto's Thyroiditis is associated with a high level of these thyroid autoantibodies in the blood. Whether the antibodies cause the disease or whether the disease causes the antibodies is not known; however, the finding of a high level of thyroid antibodies is strong evidence of this disease. Occasionally, low levels of thyroid antibodies are found with other types of thyroid disease. When Hashimoto's thyroiditis presents as a thyroid nodule rather than a diffuse goiter, the thyroid antibodies may not be present.

Thyroid Needle Biopsy. This has become the most reliable test to differentiate the "cold" nodule that is cancer from the "cold" nodule that is benign ("hot" nodules are rarely cancerous). It provides information that no other thyroid test will provide. While not perfect, it will provide definitive information in 75% of the nodules biopsied. A very extensive discussion of Thyroid Needle Biopsy is found on another page.

Since Euthyrox or Synthroid (and most other thyroid pills) behave exactly as normal human thyroid hormone, they are not rapidly cleared from the body as other medications are. Most thyroid pills have a half life of 6.7 days which means they must be stopped for four to five weeks (five half lives) before accurate thyroid testing is possible. An exception to the long half life of thyroid medication is Cytomel - a thyroid pill with a half life of only forty-eight hours. Therefore it is possible to change a person's thyroid replacement to Cytomel for one month to allow time for his regular pills to clear the body. Cytomel is then stopped for ten days (five half lives) and the appropriate immunoassay test can then be done. Usually patients, even those who have no remaining thyroid function, tolerate being off thyroid replacement only ten days quite well.

How is it used?

TSH testing is used to:

diagnose a thyroid disorder in a person with symptoms,
screen healthy adults for thyroid disorders as recommended by the American Thyroid Association,
screen newborns for an underactive thyroid,
monitor thyroid replacement therapy in people with hypothyroidism, and
diagnose and monitor female infertility problems.

Thyroid Tests

When is it ordered ?

Your doctor orders this test if you show symptoms of a thyroid disorder. For example, symptoms of hyperthyroidism include heat intolerance, weight loss, rapid heartbeat, nervousness, insomnia, and breathlessness.

Common symptoms of hypothyroidism include fatigue, weakness, weight gain, slow heart rate, and cold intolerance.

The blood test may be ordered with other thyroid hormone tests and after a physical examination of your thyroid. TSH screening is routinely performed in newborns. The American Thyroid Association recommends that adults older than age 35 be screened for thyroid disease every five years.

What does the test result mean?

A high TSH result often means an underactive thyroid gland caused by failure of the gland (hypothyroidism). Rarely, a high TSH result can indicate a problem with the pituitary gland, such as a tumor, in what is known as secondary hyperthyroidism. A high TSH value can also occur in people with underactive thyroid glands who have been receiving too little thyroid hormone medication.

A low TSH result can indicate an overactive thyroid gland (hyperthyroidism). A low TSH result can also indicate damage to the pituitary gland that prevents it from producing TSH. A low TSH result can also occur in people with an underactive thyroid gland who are receiving too much thyroid hormone medication.

In most cases, test results are reported as numerical values rather than as "high" or "low", "positive" or "negative", or "normal". In these instances, it is necessary to know the reference range for the particular test. However, reference ranges may vary by the patient's age, sex, as well as the instrumentation or kit used to perform the test. To learn more about reference ranges, please see the article, Reference Ranges and What They Mean. To learn the reference range for your test, consult your doctor.

Is there anything else I should know?

Many medications — including aspirin and thyroid-hormone replacement therapy — may interfere with thyroid gland function test results, so tell your doctor about any drugs you are taking.

When your doctor adjusts your dose of thyroid hormone, make sure you wait at least one to two months before you check your TSH again, so that your new dose can have its full effect.

Extreme stress and acute illness may also affect TSH test results, and results may be low during the first trimester of pregnancy.

Normal thyroid gland is shaped like a butterfly

The thyroid gland is the biggest gland in the neck. It is situated in the anterior (front) neck below the skin and muscle layers. The thyroid gland takes the shape of a butterfly with the two wings being represented by the left and right thyroid lobes which wrap around the trachea. The sole function of the thyroid is to make thyroid hormone. This hormone has an effect on nearly all tissues of the body where it increases cellular activity. The function of the thyroid therefore is to regulate the body's metabolism.
thyroid cancer tumor surgery operation condition thyroid parathyroid disease disease tumor

The thyroid gland is prone to several very distinct problems, some of which are extremely common. These problems can be broken down into [1] those concerning the production of hormone (too much, or too little), [2] those due to increased growth of the thyroid causing compression of important neck structures or simply appearing as a mass in the neck, [3] the formation of nodules or lumps within the thyroid which are worrisome for the presence of thyroid cancer, and [4] those which are cancerous. Each thyroid topic is addressed separately and illustrated with actual patient x-rays and pictures to make them easier to understand. The information on this web site is arranged to give you more detailed and complex information as you read further.

Your thyroid gland is a small gland, normally weighing less than one ounce, located in the front of the neck. It is made up of two halves, called lobes, that lie along the windpipe (trachea) and are joined together by a narrow band of thyroid tissue, known as the isthmus.

The thyroid is situated just below your "Adams apple" or larynx. During development (inside the womb) the thyroid gland originates in the back of the tongue, but it normally migrates to the front of the neck before birth. Sometimes it fails to migrate properly and is located high in the neck or even in the back of the tongue (lingual thyroid) This is very rare. At other times it may migrate too far and ends up in the chest (this is also rare).

The function of the thyroid gland is to take iodine, found in many foods, and convert it into thyroid hormones: thyroxine (T4) and triiodothyronine (T3). Thyroid cells are the only cells in the body which can absorb iodine. These cells combine iodine and the amino acid tyrosine to make T3 and T4. T3 and T4 are then released into the blood stream and are transported throughout the body where they control metabolism (conversion of oxygen and calories to energy). Every cell in the body depends upon thyroid hormones for regulation of their metabolism. The normal thyroid gland produces about 80% T4 and about 20% T3, however, T3 possesses about four times the hormone "strength" as T4.

Hypothalamus secretes TRH, Pituitary secretes TSH, Thyroid secretes T3 and T4.

Hypothalamus secretes TRH, Pituitary secretes TSH, Thyroid secretes T3 and T4.

The thyroid gland is under the control of the pituitary gland, a small gland the size of a peanut at the base of the brain (shown here in orange). When the level of thyroid hormones (T3 & T4) drops too low, the pituitary gland produces Thyroid Stimulating Hormone (TSH) which stimulates the thyroid gland to produce more hormones. Under the influence of TSH, the thyroid will manufacture and secrete T3 and T4 thereby raising their blood levels. The pituitary senses this and responds by decreasing its TSH production. One can imagine the thyroid gland as a furnace and the pituitary gland as the thermostat. Thyroid hormones are like heat. When the heat gets back to the thermostat, it turns the thermostat off. As the room cools (the thyroid hormone levels drop), the thermostat turns back on (TSH increases) and the furnace produces more heat (thyroid hormones).

The pituitary gland itself is regulated by another gland, known as the hypothalamus (shown in our picture in light blue). The hypothalamus is part of the brain and produces TSH Releasing Hormone (TRH) which tells the pituitary gland to stimulate the thyroid gland (release TSH). One might imagine the hypothalamus as the person who regulates the thermostat since it tells the pituitary gland at what level the thyroid should be set.

Hypothyroidism is a condition in which the body lacks sufficient thyroid hormone. Since the main purpose of thyroid hormone is to "run the body's metabolism", it is understandable that people with this condition will have symptoms associated with a slow metabolism. Over five million Americans have this common medical condition. In fact, as many as ten percent of women may have some degree of thyroid hormone deficiency. Hypothyroidism is more common than you would believe...and, millions of people are currently hypothyroid and don't know it! [For an overview of how thyroid hormone is produced and how its production is regulated check out our thyroid hormone production page.]

There are two fairly common causes of hypothyroidism. The first is a result of previous (or currently ongoing) inflammation of the thyroid gland which leaves a large percentage of the cells of the thyroid damaged (or dead) and incapable of producing sufficient hormone. The most common cause of thyroid gland failure is called autoimmune thyroiditis (also called Hashimoto's thyroiditis), a form of thyroid inflammation caused by the patient's own immune system. The second major cause is the broad category of "medical treatments". As noted on a number of our other pages, the treatment of many thyroid conditions warrants surgical removal of a portion or all of the thyroid gland. If the total mass of thyroid producing cells left within the body are not enough to meat the needs of the body, the patient will develop hypothyroidism. Remember, this is often the goal of the surgery as seen in surgery for thyroid cancer. But at other times, the surgery will be to remove a worrisome nodule,leaving half of the thyroid in the neck undisturbed. Sometimes (often), this remaining thyroid lobe and isthmus will produce enough hormone to meet the demands of the body. For other patients, however, it may become apparent years later that the remaining thyroid just can't quite keep up with demand. Similarly, goiters and some other thyroid conditions can be treated with radioactive iodine therapy. The aim of the radioactive iodine therapy (for benign conditions) is to kill a portion of the thyroid to [1] prevent goiters from growing larger, or [2] producing too much hormone (hyperthyroidism). Occasionally, (often?) the result of radioactive iodine treatment will be that too many cells are damaged so the patient often becomes hypothyroid a year or two later. This is O.K. and usually greatly preferred over the original problem. There are several other rare causes of hypothyroidism, one of them being a completely "normal" thyroid gland which is not making enough hormone because of a problem in the pituitary gland. If the pituitary does not produce enough Thyroid Stimulating Hormone (TSH) then the thyroid simply does not have the "signal" to make hormone, so it doesn't.

Fatigue
Weakness
Weight gain or increased difficulty losing weight
Coarse, dry hair
Dry, rough pale skin
Hair loss
Cold intolerance (can't tolerate the cold like those around you)
Muscle cramps and frequent muscle aches
Constipation
Depression
Irritability
Memory loss
Abnormal menstrual cycles
Decreased libido

Each individual patient will have any number of these symptoms which will vary with the severity of the thyroid hormone deficiency and the length of time the body has been deprived of the proper amount of hormone. Some patients will have one of these symptoms as their main complaint, while another will not have that problem at all and will be suffering from a different symptom. Most will have a combination of a number of these symptoms. Occasionally, some patients with hypothyroidism have no symptoms at all, or they are just so subtle that they go unnoticed. Note: Although this may sound obvious, if you have these symptoms, you need to discuss them with your doctor and probably seek the skills of an endocrinologist. If you have already been diagnosed and treated for hypothyroidism and you continue to have any or all of these symptoms, you need to discuss it with your physician. Although treatment of hypothyroidism can be quite easy in some individuals, others will have a difficult time finding the right type and amount of replacement thyroid hormone. (More about this on the next page).

Because the body is expecting a certain amount of thyroid hormone the pituitary will make additional thyroid-stimulating-hormone (TSH) in an attempt to entice the thyroid to produce more hormone. This constant bombardment with high levels of TSH may cause the thyroid gland to become enlarged and form a goiter (termed a "compensatory goiter"). Our goiter page goes into this topic in detail, and outlines that a deficiency of thyroid hormone is a common cause of goiter formation. Left untreated, the symptoms of hypothyroidism will usually progress. Rarely, complications can result in severe life-threatening depression, heart failure or coma.

Hypothyroidism can often be diagnosed with a simple blood test. In some persons, however, its not so simple and more detailed tests are needed. Most importantly, a good relationship with a good endocrinologist will almost surely be needed.

Hypothyroidism is completely treatable in many patients simply by taking a small pill once a day! Once again, however, we have made a simplified statement and its not always so easy. There are several types of thyroid hormone preparations and one type of medicine will not be the best therapy for all patients. Many factors will go into the treatment of hypothyroidism and it is different for everybody.

Since hypothyroidism is caused by too little thyroid hormone secreted by the thyroid, the diagnosis is based almost exclusively upon measuring the amount of thyroid hormone in the blood. There are normal ranges which have been calculated by computers which measured these hormones in tens of thousands of people. If your hormone levels fall below the normal range, that is consistent with hypothyroidism. These tests are very accurate and reliable and are so routine that they are available to everybody. However, its not always so simple...keep reading.

The idea is to measure blood levels of T4 and TSH. In the typical person with an under-active thyroid gland, the blood level of T4 (the main thyroid hormone) will be low, while the TSH level will be high. This means that the thyroid is not making enough hormone and the pituitary recognizes it and is responding appropimmunoassaytely by making more Thyroid Stimulating Hormone (TSH) in an attempt to force more hormone production out of the thyroid. In the more rare case of hypothyroidism due to pituitary failure, the thyroid hormone T4 will be low, but the TSH level will also be low. The thyroid is behaving "appropimmunoassaytely" under these conditions because it can only make hormone in response to TSH signals from the pituitary. Since the pituitary is not making enough TSH, then the thyroid will never make enough T4. The real question in this situation is what is wrong with the pituitary? But in the typical and most common form of hypothyroidism, the main thyroid hormone T4 is low, and the TSH level is high.

The next question is: When is low too low, and when is high too high? Blood levels have "normal" ranges, but other factors need to be taken into account as well, such as the presence or absence of symptoms. You should discuss your levels with your doctor so you can interpret how they are helping (or not?) fix your problems.

Oh, if only it were this simple all the time! Although the majority of individuals with hypothyroidism will be easy to diagnose with these simple blood tests, many millions will have this disease in mild to moderate forms which are more difficult to diagnose. The solution for these people is more complex and this is due to several factors. First we must realize that not all patients with hypothyroidism are the same. There are many degrees of this disease from very severe to very mild. Additionally, and very importantly, we cannot always predict just how bad (or good) an individual patient will feel just by examining his/her thyroid hormone levels. In other words, some patients with very "mild" deviations in their thyroid laboratory test results will feel just fine while others will be quite symptomatic. The degree of thyroid hormone abnormalities often, but NOT ALWAYS will correlate with the degree of symptoms. It is important for both you and your physician to keep this in mind since the goal is not necessarily to make the lab tests go into the normal range, but to make you feel better as well! We must also keep in mind that even the "normal" thyroid hormone levels in the blood have a fairly large range, so even if a patient is in the "normal" range, it may not be the normal level for them.

For the majority of patients with hypothyroidism, taking some form of thyroid hormone replacement (synthetic or natural, pill or liquid, etc) will make the "thyroid function tests" return to the normal range, AND, this is accompanied by a general improvement in symptoms making the patient feel better. This does not happen to all individuals, however, and for these patients it is very important to find an endocrinologist who will listen and be sympathetic. (We aim to help you find this type of doctor.) Because most patients will be improved (or made completely better) when sufficient thyroid hormone is provided on a daily basis to make the hormone levels in the blood come into the normal range, physicians will often will rely on test results to determine when a patient is on the appropimmunoassayte dose and therefore doing well. Remember, these tests have a wide normal range. Find a doctor who helps make you FEEL better, not just make your labs better because once given this diagnosis, you are likely to carry it for a long, long time. There is more than one drug, there is more than one lab test, and there is a "just right" doctor for everybody.

Hypothyroidism is usually quite easy to treat (for most people)! The easiest and most effective treatment is simply taking a thyroid hormone pill (Levothyroxine) once a day, preferably in the morning. This medication is a pure synthetic form of T4 which is made in a laboratory to be an exact replacement for the T4 that the human thyroid gland normally secretes. It comes in multiple strengths, which means that an appropimmunoassayte dosage can almost always be found for each patient. The dosage should be re-evaluated and possibly adjusted monthly until the proper level is established. The dose should then be re-evaluated at least annually. If you are on this medication, make sure your physician knows it so he/she can check the levels at least yearly. Note: Just like we discussed above, however, this simple approach does not hold true for everybody. Occasionally the correct dosage is a bit difficult to pin-point and therefore you may need an exam and blood tests more frequently. Also, some patients just don't do well on some thyroid medications and will be quite happy on another. For these reasons you should not be shy in discussing with your doctor your blood hormone tests, symptoms, how you feel, and the type of medicine you are taking. The goal is to make you feel better, make your body last longer, slow the risk of heart disease and osteoporosis...in addition to making your blood levels normal! Sometimes that's easy, when its not, you need a physician who is willing to spend the time with you that you deserve while you explore different dosages other types of medications (or alternative diagnoses).

Some patients will notice a slight reduction in symptoms within 1 to 2 weeks, but the full metabolic response to thyroid hormone therapy is often delayed for a month or two before the patient feels completely normal. It is important that the correct amount of thyroid hormone is used. Not enough and the patient may have continued fatigue or some of the other symptoms of hypothyroidism. Too high a dose could cause symptoms of nervousness, palpitations or insomnia typical of hyperthyroidism. Some recent studies have suggested that too much thyroid hormone may cause increased calcium loss from bone increasing the patient's risk for osteoporosis. For patients with heart conditions or diseases, an optimal thyroid dose is particularly important. Even a slight excess may increase the patient's risk for heart attack or worsen angina. Some physicians feel that more frequent dose checks and blood hormone levels are appropimmunoassayte in these patients.

After about one month of treatment, hormone levels are measured in the blood to establish whether the dose of thyroid hormone which the patient is taking is appropimmunoassayte. We don't want too much given or subtle symptoms of hyperthyroidism could ensue, and too little would not alleviate the symptoms completely. Often blood samples are also checked to see if there are antibodies against the thyroid, a sign of autoimmune thyroiditis. Remember, this is the most common cause of hypothyroidism. Once treatment for hypothyroidism has been started, it typically will continue for the patient's life. Therefore, it is of great importance that the diagnosis be firmly established and you have a good relationship with a physician you like and trust.

Synthetic T4 can be safely taken with most other medications. Patients taking cholestyramine (a compound used to lower blood cholesterol) or certain medications for seizures should check with their physician about potential interactions. Women taking T4 who become pregnant should feel confident that the medication is exactly what their own thyroid gland would otherwise make. However, they should check with their physician since the T4 dose may have to be adjusted during pregnancy (usually more hormone is needed to meet the increased demands of the mother's new increased metabolism). There are other potential problems with other drugs including iron-containing vitamins. Once again, pregnant women (and all women and men for that matter) taking iron supplements should discuss this with your physician. There are three brand name Levothyroxine tablets now available. You may want to consult with your physician or pharmacist on the most cost effective brand since recent studies suggest that none is better than the other.

Thyroiditis is an inflammation (not an infection) of the thyroid gland. Several types of thyroiditis exist and the treatment is different for each.

Hashimoto's Thyroiditis. Hashimoto's Thyroiditis (also called autoimmune or chronic lymphocytic thyroiditis) is the most common type of thyroiditis. It is named after the Japanese physician, Hakaru Hashimoto, that first described it in 1912. The thyroid gland is always enlarged, although only one side may be enlarged enough to feel. During the course of this disease, the cells of the thyroid becomes inefficient in converting iodine into thyroid hormone and "compensates" by enlarging. The radioactive iodine uptake may be paradoxically high while the patient is hypothyroid because the gland retains the ability to take-up or "trap" iodine even after it has lost its ability to produce thyroid hormone. As the disease progresses, the TSH increases since the pituitary is trying to induce the thyroid to make more hormone, the T4 falls since the thyroid can't make it, and the patient becomes hypothyroid. The sequence of events can occur over a relatively short span of a few weeks or may take several years.

Treatment is to start thyroid hormone replacement. This prevents or corrects the hypothyroidism and it also generally keeps the gland from getting larger.

In most cases the thyroid gland will decrease in size once thyroid hormone replacement is started.

Thyroid antibodies are present in 95% of patients with Hashimoto's Thyroiditis and serve as a useful "marker" in identifying the disease without thyroid biopsy or surgery.

Thyroid antibodies may remain for years after the disease has been adequately treated and the patient is on thyroid hormone replacement.

De Quervain's Thyroiditis. De Quervain's Thyroiditis (also called subacute or granulomatous thyroiditis) was first described in 1904 and is much less common than Hashimoto's Thyroiditis. The thyroid gland generally swells rapidly and is very painful and tender. The gland discharges thyroid hormone into the blood and the patients become hyperthyroid; however the gland quits taking up iodine (radioactive iodine uptake is very low) and the hyperthyroidism generally resolves over the next several weeks.

Patients frequently become ill with fever and prefer to be in bed.

Thyroid antibodies are not present in the blood, but the sedimentation rate, which measures inflammation, is very high.

Although this type of thyroiditis resembles an infection within the thyroid gland, no infectious agent has ever been identified and antibiotics are of no use.

Treatment is usually bed rest and aspirin to reduce inflammation.

Occasionally cortisone (steroids) (to reduce inflammation) and thyroid hormone (to "rest" the thyroid gland) may be used in prolonged cases.

Nearly all patients recover and the thyroid gland returns to normal after several weeks or months.

A few patients will become hypothyroid once the inflammation settles down and therefore will need to stay on thyroid hormone replacement indefinitely.

Recurrences are uncommon.

Silent Thyroiditis. Silent Thyroiditis is the third and least common type of thyroiditis. It was not recognized until the 1970's although it probably existed and was treated as Graves' Disease before that. This type of thyroiditis resembles in part Hashimoto's Thyroiditis and in part De Quervain's Thyroiditis. The blood thyroid test are high and the radioactive iodine uptake is low (like De Quervain's Thyroiditis), but there is no pain and needle biopsy resembles Hashimoto's Thyroiditis. The majority of patients have been young women following pregnancy. The disease usually needs no treatment and 80% of patients show complete recovery and return of the thyroid gland to normal after three months. Symptoms are similar to Graves' Disease except milder. The thyroid gland is only slightly enlarged and exophthalmos (development of "bug eyes") does not occur. Treatment is usually bed rest with beta blockers to control palpitations (drugs to prevent rapid heart rates). Radioactive iodine, surgery, or antithyroid medication is never needed. A few patients have become permanently hypothyroid and needed to be placed on thyroid hormone.

Basic facts about thyroid nodules

Simply put, thyroid nodules are lumps which commonly arise within an otherwise normal thyroid gland. Often these abnormal growths of thyroid tissue are located at the edge of the thyroid gland so they can be felt as a lump in the throat. When they are large or when they occur in very thin individuals, they can even sometimes be seen as a lump in the front of the neck. The following is a list of facts regarding thyroid nodules:

After an appropimmunoassayte work-up, most thyroid nodules will yield an answer of NO to all of the above questions. In this most common situation, there is a small to moderate sized nodule which is simply an overgrowth of "normal" thyroid tissue, or even a sign that there is too little hormone being produced. Patients with a diffusely enlarged thyroid (called a goiter) will present with what is perceived at first to be a nodule, but later found to be only one of many benign enlarged growths within the thyroid (a goiter). Usually a fine needle aspiration biopsy (FNA) will tell if the nodule is cancerous or benign. This one test can get right to the bottom of the issue (covered in detail on another page). Often an Ultrasound examination is necessary to determine the characteristics of a thyroid nodule (ultrasound is covered in detail on another page)

Symptoms of thyroid nodules

Most thyroid nodules cause no symptoms at all. They are usually found by patients who feel a lump in their throat or see it in the mirror. Occasionally, a family member or friend will notice a strange lump in the neck of someone with a thyroid nodule. Another common way in which thyroid nodules are found is during a routine examination by a physician.

Occasionally, nodules may cause pain, and even rarer still are those patients who complain of difficulty swallowing when a nodule is large enough and positioned in such a way that it impedes the normal passage of food through the esophagus (which lies behind the trachea and thyroid).

I have a nodule !! What do I do ??

First of all, remember that the vast majority of thyroid nodules are benign. Next, the nodule should be evaluated by a physician who is comfortable with this problem. Endocrinologists and Endocrine Surgeons deal with these problems on a regular basis, but many family practice physicians, general internists, and general surgeons are also adept at addressing thyroid nodules. This is covered in more detail on our nodule exam/biopsy page.

One of the first things that a physician will do will be to ask a number of important questions regarding your health and potential thyroid problems. These questions include whether or not you have been exposed to nuclear radiation or received radiation treatments as a child or teenager.

What about radiation exposure ??

Ionizing radiation has been known for a number of years to be associated with a SMALL increased risk of developing thyroid cancer. The risk is very small and the amount of radiation exposure is usually quite high. There is typically a delay of 20 years or more between radiation exposure and the development of thyroid cancer.

Radiation was used occasionally between the 1920's and 1950's to treat certain neck infections such as recurrent tonsillitis as well as certain skin conditions such as severe acne.

In July, 1997 the U.S. government announced the results of a scientific study to determine if the nuclear weapons testing in the Southeast U.S. from 1945 through the 1970's would have an effect on the development of thyroid cancer in Americans. This epidemiological study determined that these nuclear tests would likely increase the amount of thyroid cancers seen in Americans over the next several decades. The risks are substantially greater for those patients living nearby the test sites for many years. If there is any good news to this report, it is that these cancers will typically be of the well differentiated type which have an excellent prognosis...the vast majority of these can be cured. There is NO evidence that children are at increased risk of developing thyroid cancer, the small increase risk appears to be limited to those that were directly exposed in the past. Despite these increased risks, thyroid cancer is still relatively uncommon and usually very curable.

Solitary dominant nodule of right thyroid lobe

Thyroid nodules increase with age and are present in almost ten percent of the adult population. Autopsy studies reveal the presence of thyroid nodules in 50 percent of the population, so they are fairly common. Ninety-five percent of solitary thyroid nodules are benign, and therefore, only five percent of thyroid nodules are malignant. Common types of the benign thyroid nodules are adenomas (overgrowths of "normal" thyroid tissue), thyroid cysts, and Hashimoto's thyroiditis. Uncommon types of benign thyroid nodules are due to subacute thyroiditis, painless thyroiditis, unilateral lobe agenesis, or Riedel's struma. As noted on previous pages, those few nodules which are cancerous are usually due to the most common types of thyroid cancers which are the differentiated" thyroid cancers. Papillary carcinoma accounts for 60 percent, follicular carcinoma accounts for 12 percent, and the follicular vaimmunoassaynt of papillary carcinoma accounting for six percent. These well differentiated thyroid cancers are usually curable, but they must be found first. Fine needle biopsy is a safe, effective, and easy way to determine if a nodule is cancerous.

Thyroid cancers typically present as a dominant solitary thyroid nodule which can be felt by the patient or even seen as a lump in the neck by his/her family and friends. This is illustrated in the picture above. As pointed out on our page introducing thyroid nodules, we must differentiate benign nodules from cancerous solitary thyroid nodules. While history, examination by a physician, laboratory tests, ultrasound, and thyroid scans (shown in the picture below) can all provide Solitary cold nodule of thyroid

information regarding a solitary thyroid nodule, the only test which can differentiate benign from cancerous thyroid nodules is a biopsy (the term biopsy means to obtain a sample of the tissue and examine it under the microscope to see if the cells have taken on the characteristics of cancer cells). Thyroid cancer is no different in this situation from all other tissues of the body...the only way to see if something is cancerous is to biopsy it. However, thyroid tissues are easily accessible to needles, so rather than operating to remove a chunk of tissue with a knife, we can stick a very small needle into it and remove cells for microscopic examination. This method of biopsy is called a fine needle aspiration biopsy, or "FNA".

What is a cold nodule? Thyroid cells absorb iodine so they can make thyroid hormone out of it. When radioactive iodine is given, a butterfly image will be obtained on x-ray film showing the outline of the thyroid. If a nodule is composed of cells which do not make thyroid hormone (don't absorb iodine) then it will appear "cold" on the x-ray film. A nodule which is producing too much hormone will show up darker and is called "hot". [A hot nodule is shown on our page describing the causes of hyperthyroidism].

The evaluation of a solitary thyroid nodule should always include history and examination by a physician. Certain aspects of the history and physical exam will suggest a benign or malignant condition. Remember, a biopsy of some sort is the only way to tell for sure.

family history of Hashimoto's thyroiditis

family history of benign thyroid nodule or goiter

symptoms of hyperthyroidism or hypothyroidism

pain or tenderness associated with a nodule

a soft, smooth, mobile nodule

multinodular goiter without a predominant nodule (lots of nodules, not one main nodule)

"warm" nodule on thyroid scan (produces normal amount of hormone)

simple cyst on ultrasound

age less than 20

age greater than 70

male gender

new onset of swallowing difficulties

new onset of hoarseness

history of external neck irradiation during childhood

firm, irregular and fixed nodule

presence of cervical lymphadenopathy (swollen hard lymph nodes in the neck)

previous history of thyroid cancer

nodule that is "cold" on scan (shown in picture above, meaning the nodule does not make hormone)

solid or complex on ultrasound

Thyroid hormone levels are usually normal in the presence of a nodule, and normal thyroid hormone levels do not differentiate benign from cancerous nodules. However, the presence of hyperthyroidism or hypothyroidism favors a benign nodule (thats why a "warm" nodule or a "hot" nodule favors a benign condition). Thyroglobulin levels are useful tumor markers once the diagnosis of malignancy has been made, but are nonspecific in regard to differentiating a benign from a cancerous thyroid nodule. Ultrasound accurately determines thyroid gland volume, number and size of nodules; separates thyroid from nonthyroidal masses; helps guide fine needle biopsy when necessary; and can identify solid nodules as small as 3 mm and cystic nodules as small as 2 mm. Although several ultrasound features favor the presence of a benign nodule, and other ultrasound features favor the presence of a cancerous nodule. Ultrasound alone cannot be used to differentiate benign from malignant nodules. This is covered more completely on our nodule/ultrasound page. And since 15 percent of cystic thyroid nodules are malignant, ultrasound determination that a nodule is cystic does not rule out thyroid cancer.

Nodules detected by thyroid scans are classified as cold, hot or warm. Eighty-five percent of thyroid nodules are cold, 10 percent are warm, and five percent are hot. An excellent example of a cold scan is shown above, but remember that 85 percent of cold nodules are benign, 90 percent of warm nodules are benign, and 95 percent of hot nodules are benign. Although thyroid scanning can give a probability that a nodule is benign or malignant, it cannot truly differentiate benign or malignant nodules and usually should not be used as the only basis for recommending treatment of the nodule, including thyroid surgery.

Thyroid fine needle aspiration (FNA) biopsy is the only non-surgical method which can differentiate malignant and benign nodules in most, but not all, cases. The needle is placed into the nodule several times and cells are aspirated into a syringe. The cells are placed on a microscope slide, stained, and examined by a pathologist. The nodule is then classified as nondiagnostic, benign, suspicious or malignant.

FNA is the first, and in the vast majority of cases, the only test required for the evaluation of a solitary thyroid nodule. (A TSH value should also be obtained to evaluate thyroid function.) Thyroid ultrasound and thyroid scans are usually not required for evaluation of a solitary thyroid nodule. FNA has reduced the cost for evaluation and treatment of thyroid nodules, and has improved yield of cancer found at thyroid surgery. Although a solitary thyroid nodule can enlarge or shrink over time, the natural history of solitary nodules reveals that most nodules change little with time.

Several studies reveal that suppression with thyroid hormone does not decrease the size of thyroid nodules. Therefore, unless a nodule is growing or becoming symptomatic, it is not necessary to suppress the nodule. In addition, suppression of a thyroid nodule would require long-term TSH suppression, potentially increasing the risk of osteoporosis in these patients. While there has been a traditional distinction between thyroid glands with a solitary nodule and multinodular goiters, it has been shown that approximately 50 percent of patients with a solitary nodule on exam will have additional nodules on thyroid ultrasound. Therefore, the differentiation between solitary nodules and multinodular goiters is becoming less clear-cut. It has also been believed for many years that the presence of a multinodular goiter reduces the likelihood that a thyroid cancer is present, yet recent studies indicate that there might be an equal likelihood for developing thyroid cancer in a multinodular goiter just as in a solitary thyroid nodule. If a multinodular goiter has a predominant nodule, the predominant nodule should be biopsied.

In conclusion, FNA of the thyroid is a safe, inexpensive and effective way to distinguish a benign from a malignant nodule and usually should be the first diagnostic test performed.

Once a thyroid nodule has been detected (or suspected), there are a few things that the physician wants to know before any recommendations can be made regarding what actions to take. Remember, the vast majority of thyroid nodules are benign and nothing to worry about, so the focus is on determining which ones have any reasonable chance of being cancerous. It is those few worrisome nodules which will need to be operated upon with that portion of the thyroid removed.

One of the first tests which is routinely performed is the Fine Needle Aspiration Biopsy. The FNA will usually (but not always) tell if a nodule is benign or malignant. Often this is the only test which is needed. The use of FNA and a lot more information about the potential for a thyroid nodule to be malignant is on another page.

Another test which is routinely performed is the ultrasound. This simple test uses sound waves to image the thyroid. The sound waves are emitted from a small hand-held transducer which is passed over the thyroid. A lubricant jelly is placed on the skin so that the sound waves transmit easier through the skin and into the thyroid and surrounding structures. This test is quick, accurate, cheap, painless, and completely safe. It usually takes only about 10 minutes and the results can be known almost immediately. Not all nodules need this test, but it is almost routine.

This is an ultrasound of a typical thyroid nodule...except that this nodule is a bit bigger than usual. The two scans are identical, I just outlined the one on the right to help you understand what you are looking at. The probe is placed on the skin which is at the very top of the picture and sound waves are directed deep into the neck and thyroid (toward the bottom of the picture). As sound waves hit structures they bounce back like an echo. The probe detects these reflections to make pictures. This nodule (shown in red) comprises about 80% of the thyroid tissue (shown in yellow) in this particular area of the thyroid. If you looked at other parts of the thyroid, however, you would not see the nodule and you would only see normal thyroid tissue.

There are certain characteristics of thyroid nodules seen on ultrasound which are more worrisome than others. Keep in mind, however, that ultrasound alone cannot make the diagnosis of cancer! This test will usually help tell us that the nodule has a low chance of being cancer (has characteristics of a benign nodule), or that it has some characteristics of a cancerous nodule and therefore a biopsy is indicated.

Nice sharp edges are seen all around the nodule

Nodule filled with fluid and not live tissue (a cyst)

Lots of nodules throughout the thyroid (almost always a benign multi-nodular goiter)

No blood flowing through it (not live tissue, likely a cyst)

More on this topic on our FNA Page.

To illustrate some of these points a little, the next picture shows the same ultrasound as above, but this time we programmed the probe to detect blood flow. You can now clearly see that this nodule is complex...which means that some of it is cystic, while other parts are comprised of live tissues which have a good blood supply. If this were a simple cyst filled with serous fluid, then it would have no red (artery) or blue (vein) blood flow.

This patient had no other nodules in her thyroid, so this was diagnosed as a "dominant complex nodule of the right thyroid lobe"

Since this nodule does have a few worrisome characteristics, we performed a fine needle aspirate biopsy (FNA). In this test, a very small needle is passed into the nodule and some cells are aspirated out and then placed on a glass slide for a pathologist to stain and determine if they are malignant or not. This test is very simple, takes less than 30 seconds, is virtually pain free, and can be very accurate. If it is read as cancer, this test is almost always right. Sometimes, however, there are not enough cells removed or some but not all cells look abnormal. In this case, the pathologist will not be able to tell cancer from a benign nodule. This situation usually dictates that the test be repeated or that the patient undergoes surgical removal of this part of the thyroid. Remember, the vast majority of nodules are benign, and even if it is cancer, most thyroid cancers are extremely curable!

This patient had 2 indeterminate FNA's performed. Both needle biopsies had good tissue specimens, but the pathologist could not distinguish benign from cancer. She subsequently underwent a simple right thyroid lobectomy and the final diagnosis was a benign follicular adenoma. She did fine after the operation and has enough normal thyroid still in her neck so that she does not have to take thyroid hormone pills.

This is a large topic so we have split it into four manageable sized portions.
This page introduces hyperthyroidism. Subsequent pages are listed at the bottom which
address more specific details of making the diagnosis, the causes, and different treatment options.

This little gland runs my metabolism?

In healthy people, the thyroid makes just the right amounts of two hormones, T4 and T3, which have important actions throughout the body. These hormones regulate many aspects of our metabolism, eventually affecting how many calories we burn, how warm we feel, and how much we weigh. In short, the thyroid "runs" our metabolism. These hormones also have direct effects on most organs, including the heart which beats faster and harder under the influence of thyroid hormones. Essentially all cells in the body will respond to increases in thyroid hormone with an increase in the rate at which they conduct their business. Hyperthyroidism is the medical term to describe the signs and symptoms associated with an over production of thyroid hormone. For an overview of how thyroid hormone is produced and how its production is regulated check out our thyroid hormone production page.

Hyperthyroidism means the thyroid produces too much hormone.

Hyperthyroidism means the thyroid produces too much hormone.

Hyperthyroidism is a condition caused by the effects of too much thyroid hormone on tissues of the body. Although there are several different causes of hyperthyroidism, most of the symptoms that patients experience are the same regardless of the cause (see the list of symptoms below). Because the body's metabolism is increased, patients often feel hotter than those around them and can slowly lose weight even though they may be eating more. The weight issue is confusing sometimes since some patients actually gain weight because of an increase in their appetite. Patients with hyperthyroidism usually experience fatigue at the end of the day, but have trouble sleeping. Trembling of the hands and a hard or irregular heartbeat (called palpitations) may develop. These individuals may become irritable and easily upset. When hyperthyroidism is severe, patients can suffer shortness of breath, chest pain, and muscle weakness. Usually the symptoms of hyperthyroidism are so gradual in their onset that patients don't realize the symptoms until they become more severe. This means the symptoms may continue for weeks or months before patients fully realize that they are sick. In older people, some or all of the typical symptoms of hyperthyroidism may be absent, and the patient may just lose weight or become depressed.

Palpitations

Heat intolerance

Nervousness

Insomnia

Breathlessness

Increased bowel movements

Light or absent menstrual periods

Fatigue

Fast heart rate
Trembling hands
Weight loss
Muscle weakness
Warm moist skin
Hair loss
Staring gaze

Remember, the words "signs" and "symptoms" have different medical meanings. Symptoms are those problems that a patient notices or feels. Signs are those things that a physician can objectively detect or measure. For instance, a patient will feel hot, this is a symptom. The physician will touch the patient's skin and note that it is warm and moist, this is a sign.

There are several causes of hyperthyroidism. Most often, the entire gland is overproducing thyroid hormone. Less commonly, a single nodule is responsible for the excess hormone secretion.

The most common underlying cause of hyperthyroidism is Graves' disease, a condition named for an Irish doctor who first described the condition. This condition can be summarized by noting that an enlarged thyroid (enlarged thyroids are called goiters) is producing way too much thyroid hormone. [Remember that only a small percentage of goiters produce too much thyroid hormone, the majority actually become large because they are not producing enough thyroid hormone]. Graves' disease is classified as an autoimmune disease, a condition caused by the patient's own immune system turning against the patient's own thyroid gland. The hyperthyroidism of Graves' disease, therefore, is caused by antibodies that the patient's immune system makes which attach to specific activating sites on thyroid gland which in turn cause the thyroid to make more hormone. There are actually three distinct parts of Graves' disease: [1] overactivity of the thyroid gland (hyperthyroidism), [2] inflammation of the tissues around the eyes causing swelling, and [3] thickening of the skin over the lower legs (pretibial myxedema). Most patients with Graves' disease, however, have no obvious eye involvement. Their eyes may feel irritated or they may look like they are staring. About one out of 20 people with Graves' disease will suffer more severe eye problems, which can include bulging of the eyes, severe inflammation, double vision, or blurred vision. If these serious problems are not recognized and treated, they can permanently damage the eyes and even cause blindness. Thyroid and eye involvement in Graves' disease generally run a parallel course, with eye problems resolving slowly after hyperthyroidism is controlled.

Affects women much more often than men (about 8:1)

Often called diffuse toxic goiter because the entire gland is enlarged

Uncommon over the age of 50 (more common in the 30's and 40's)

Tends to run in families (not known why)

Solitary HOT nodule in right thyroid lobe.

Hyperthyroidism can also be caused by a single nodule within the thyroid instead of the entire thyroid. As outlined in detail on our nodules page, thyroid nodules usually represent benign (non-cancerous) lumps or tumors in the gland. These nodules sometimes produce excessive amounts of thyroid hormones. This condition is called "toxic nodular goiter". The picture on the right is an iodine scan (also simply called a thyroid scan) which shows a normal sized thyroid gland (shaped like a butterfly). This scan is abnormal because a solitary "hot" nodule is located in the right lower lobe. This single nodule is comprised of thyroid cells which have lost their regulatory mechanism which dictates how much hormone to produce. Without this regulatory control, the cells in this nodule produce thyroid hormone at a dramatically increased rate causing the symptoms of hyperthyroidism. [As a point of reference, some nodules are "cold" since they don't produce any hormone at all. There is a picture of a cold nodule on the nodule page.]

Inflammation of the thyroid gland, called thyroiditis, can lead to the release of excess amounts of thyroid hormones that are normally stored in the gland. In subacute thyroiditis, the painful inflammation of the gland is believed to be caused by a virus, and the hyperthyroidism lasts a few weeks. A more common painless form of thyroiditis occurs in one out of 20 women, a few months after delivering a baby and is, therefore, known as postpartum thyroiditis. Although hyperthyroidism caused by thyroiditis causes the typical symptoms listed on our introduction to hyperthyroidism page, they generally last only a few weeks until the thyroid hormone stored in the gland has been exhausted. For more about thyroiditis see our page on this topic.

Hyperthyroidism can also occur in patients who take excessive doses of any of the available forms of thyroid hormone. This is a particular problem in patients who take forms of thyroid medication that contains T3, which is normally produced in relatively small amounts by the human thyroid gland. Other forms of hyperthyroidism are even rarer. It is important for your doctor to determine which form of hyperthyroidism you may have since the best treatment options will change depending on the underlying cause.

Thyroid produces T3 and T4 in response to TSH.

The actual diagnosis of hyperthyroidism is easy to make once its possibility is entertained. Accurate and widely available blood tests can confirm or rule out the diagnosis quite easily within a day or two. Levels of the thyroid hormones themselves, T4 and T3 are measured in blood and one or both must be high for this diagnosis to be made. It is also useful to measure the level of thyroid-stimulating hormone (TSH). This hormone is secreted from the pituitary gland (shown in orange) with the purpose of stimulating the thyroid to produce thyroid hormone. The pituitary constantly monitors our thyroid hormone levels and, if it senses the slightest excess of thyroid hormone in blood, it stops producing TSH. Consequently, a low blood TSH strongly suggests that the thyroid is overproducing hormone on its own. Other special tests are occasionally use to distinguish among the various causes of hyperthyroidism. Because the thyroid gland normally takes up iodine in order to make thyroid hormones, measuring how much radioactive iodine or technetium is captured by the gland can be a very useful way to measure its function. The dose of radiation with these tests is very small and has no side effects. Such radioactive thyroid scan and uptake tests are often essential to know what treatment should be used in a patient with hyperthyroidism. This is easily demonstrated on our causes of hyperthyroidism page which shows a hot nodule.

Thyroid stimulating hormone (TSH) produced by the pituitary [will be decreased in hyperthyroidism]

Thyroid hormones themselves (T3, T4, T7) [will be increased]

Iodine thyroid scan [will show if the cause is a single nodule or the whole gland]

There are over 11,000 new cases of thyroid cancer each year in the United States. Females are more likely to have thyroid cancer at a ratio of three to one. Thyroid cancer can occur in any age group, although it is most common after age 30 and its aggressiveness increases significantly in older patients. The majority of patients present with a nodule on their thyroid which typically does not cause symptoms.
Cold nodule in thyroid

Occasionally, symptoms such as hoarseness, neck pain, and enlarged lymph nodes do occur. Although as much as 10 % of the population will have thyroid nodules, the vast majority are benign. Only approximately 5% of all thyroid nodules are malignant. A nodule which is cold on scan (shown in photo outlined in red and yellow) is more likely to be malignant, nevertheless, the majority of these are benign as well.

Most thyroid cancers are very curable. In fact, the most common types of thyroid cancer (papillary and follicular) are the most curable. In younger patients, both papillary and follicular cancers can be expected to have better than 95% cure rate if treated appropimmunoassaytely. Both papillary and follicular cancers are typically treated with complete removal of the lobe of the thyroid which harbors the cancer, PLUS, removal of most or all of the other side.

Medullary cancer of the thyroid is significantly less common, but has a worse prognosis. Medullary cancers tend to spread to large numbers of lymph nodes very early on, and therefore requires a much more aggressive operation than does the more localized cancers such as papillary and follicular. This cancer requires complete thyroid removal PLUS a dissection to remove the lymph nodes of the front and sides of the neck.

The least common type of thyroid cancer is anaplastic which has a very poor prognosis...it tends to be found after it has spread and is not cured in most cases. Often an operation cannot remove all the tumor.

Thyroid cancer is unique among cancers, in fact, thyroid cells are unique among all cells of the human body. They are the only cells which have the ability to absorb Iodine. Iodine is required for thyroid cells to produce thyroid hormone, so they absorb it out of the bloodstream and concentrate it inside the cell. Most thyroid cancer cells retain this ability to absorb and concentrate iodine. This provides a perfect "chemotherapy" strategy. Radioactive Iodine is given to the patient and the remaining thyroid cells (and any thyroid cancer cells retaining this ability) will absorb and concentrate it. Since all other cells of our bodies cannot absorb the toxic iodine, they are unharmed. The thyroid cancer cells, however, will concentrate the poison within themselves and the radioactivity destroys the cell from within. No sickness. No hair loss. No nausea. No diarrhea. No pain. More about this on the pages for each specific thyroid cancer type.

Not all patients with thyroid cancer need radioactive iodine treatments after their surgery. This is important to know. Others, however, should have it if a cure is to be expected. Just who needs it and who doesn't is a bit more detailed than can be outlined here. Patients with medullary cancer of they thyroid usually do not need iodine therapy...because medullary cancers almost never absorb the radioactive iodine. Some small papillary cancers treated with a total thyroidectomy may not need iodine therapy as well, but for a different reason. These cancers are often cured with simple (complete) surgical therapy alone. Important!!! This varies from patient to patient and from cancer to cancer. Don't look for easy answers here. This decision will be made between the surgeon, the patient, and the referring endocrinologist or internist. Remember, radioactive iodine therapy is extremely safe. If you need it, take it.

This page includes more advanced information on a specific type of thyroid cancer. . . Papillary Thyroid Cancer. Please read our Introduction to Thyroid Cancer page first which gives a general overview of all types of thyroid cancer since it will make this page easier to understand.

Papillary tumors are the most common of all thyroid cancers (>70%). Papillary carcinoma typically arises as an irregular, solid or cystic mass that arises from otherwise normal thyroid tissue. This cancer has a high cure rate with ten year survival rates for all patients with papillary thyroid cancer estimated at 80-90%. Cervical metastasis (spread to lymph nodes in the neck) are present in 50% of small tumors and in over 75% of the larger thyroid cancers. The presence of lymph node metastasis in these cervical areas causes a higher recurrence rate but not a higher mortality rate. Distant metastasis (spread) is uncommon, but lung and bone are the most common sites. Tumors that invade or extend beyond the thyroid capsule have a worsened prognosis because of a high local recurrence rate.

Peak onset ages 30 through 50

Females more common than males by 3 to 1 ratio

Prognosis directly related to tumor size [less than 1.5 cm (1/2 inch) good prognosis]

Accounts for 85% of thyroid cancers due to radiation exposure

Spread to lymph nodes of the neck present in more than 50% of cases

Distant spread (to lungs or bones) is very uncommon

Overall cure rate very high (near 100% for small lesions in young patients)

Thyroid gland has 2 lobes connected by an isthmus.

Considerable controversy exits when discussing the management of well differentiated thyroid carcinomas (papillary and even follicular). Some experts contend than if these tumors are small and not invading other tissues (the usual case) then simply removing the lobe of the thyroid which harbors the tumor (and the small central portion called the isthmus) will provide as good a chance of cure as removing the entire thyroid. These proponents of conservative surgical therapy relate the low rate of clinical tumor recurrence (5-20%) despite the fact that small amounts of tumor cells can be found in up to 88% of the opposite lobe thyroid tissues. They also site some studies showing an increased risk of hypoparathyroidism and recurrent laryngeal nerve injury in patients undergoing total thyroidectomy (since there is an operation on both sides of the neck). Proponents of total thyroidectomy (more aggressive surgery) site several large studies that show that in experienced hands the incidence of recurrent nerve injury and permanent hypoparathyroidism are quite low (about 2%). More importantly, these studies show that patients with total thyroidectomy followed by radioiodine therapy and thyroid suppression, have a significantly lower recurrence rate and lower mortality when tumors are greater than 1.5cm. One must remember that it is also desirable to reduce the amount of normal gland tissue that will take up radioiodine.

Based on the these studies and the above natural history and epidemiology of papillary carcinoma, the following is a typical plan: Papillary carcinomas that are well circumscribed, isolated, and less than 1cm in a young patient (20-40) without a history of radiation exposure may be treated with hemithyroidectomy and isthmusthectomy. All others should probably be treated with total thyroidectomy and removal of any enlarged lymph nodes in the central or lateral neck areas. The surgical options are covered in greater detail (with drawings) on another "surgical options" page.

Thyroid cells are unique in that they have the cellular mechanism to absorb iodine. The iodine is used by thyroid cells to make thyroid hormone. No other cell in the body can absorb or concentrate iodine. Physicians can take advantage of this fact and give radioactive iodine to patients with thyroid cancer. There are several types of radioactive iodine, with one type being toxic to cells. Papillary cancer cells absorb iodine and therefore they can be targeted for death by giving the toxic isotope (I-131). Once again, not everybody with papillary thyroid cancer needs this therapy, but those with larger tumors, spread to lymph nodes or other areas, tumors which appear aggressive microscopically, and older patients may benefit from this therapy. This is extremely individualized and no recommendations are being made here or elsewhere on this web site...too many vaimmunoassaybles are involved. But, this is an extremely effective type of "chemotherapy" will little or no potential down-sides (no hair loss, nausea, weight loss, etc.).

Uptake is enhanced by high TSH levels; thus patients should be off of thyroid replacement and on a low iodine diet for at least one to two weeks prior to therapy. It is usually given 6 weeks post surgery (this is vaimmunoassayble) can be repeated every 6 months if necessary (within certain dose limits).

Regardless of whether a patient has just one thyroid lobe and the isthmus removed, or the entire thyroid gland removed, most experts agree they should be placed on thyroid hormone for the rest of their lives. This is to replace the hormone in those who have no thyroid left, and to suppress further growth of the gland in those with some tissue left in the neck. There is good evidence that papillary carcinoma responds to thyroid stimulating hormone (TSH) secreted by the pituitary, therefore, exogenous thyroid hormone is given which results in decreased TSH levels and a lower impetus for any remaining cancer cells to grow. Recurrence and mortality rates have been shown to be lower in patients receiving suppression.

In addition to the usual cancer follow up, patients should receive a yearly chest x-ray as well as thyroglobulin levels Thyroglobulin is not useful as a screen for initial diagnosis of thyroid cancer but is quite useful in follow up of well differentiated carcinoma (if a total thyroidectomy has been performed). A high serum thyroglobulin level that had previously been low following total thyroidectomy especially if gradually increased with TSH stimulation is virtually indicative of recurrence. A value of greater than 10 ng/ml is often associated with recurrence even if an iodine scan is negative.

This page includes more advanced information on a specific type of thyroid cancer. . . Follicular Thyroid Cancer. Please read our Introduction to Thyroid Cancer page first which gives a general overview of all types of thyroid cancer since it will make this page easier to understand. Papillary, Medullary, and Anaplastic thyroid cancers are covered on separate pages.

Follicular carcinomas are the second most common thyroid cancers (~15 %). Follicular carcinoma is considered more malignant (aggressive) than papillary carcinoma. It occurs in a slightly older age group than papillary and is also less common in children. In contrast to papillary cancer, it occurs only rarely after radiation therapy. Mortality is related to the degree of vascular invasion. Age is a very important factor in terms of prognosis. Patients over 40 have a more aggressive disease and typically the tumor does not concentrate iodine as well as in younger patients. Vascular invasion is characteristic for follicular carcinoma and therefore distant metastasis is more common. Distant metastasis may occur in a small primary. Lung, bone, brain, liver, bladder, and skin are potential sites of distant spread. Lymph node involvement is far less common than in papillary carcinoma (8-13%).

Peak onset ages 40 through 60

Females more common than males by 3 to 1 ratio

Prognosis directly related to tumor size [less than 1.0 cm (3/8 inch) good prognosis]

Rarely associated with radiation exposure

Spread to lymph nodes is uncommon (~10%)

Invasion into vascular structures (veins and arteries) within the thyroid gland is common

Distant spread (to lungs or bones) is uncommon, but more common than with papillary cancer

Overall cure rate high (near 95% for small lesions in young patients), decreases with advanced age

Considerable controversy exits when discussing the management of well differentiated thyroid carcinomas (papillary and even follicular). Some experts contend than if these tumors are small and not invading other tissues (the usual case) then simply removing the lobe of the thyroid which harbors the tumor (and the small central portion called the isthmus) will provide as good a chance of cure as removing the entire thyroid. These proponents of conservative surgical therapy relate the low rate of clinical tumor recurrence (5-20%) despite the fact that small amounts of tumor cells can be found in up to 88% of the opposite lobe thyroid tissues. They also site some studies showing an increased risk of hypoparathyroidism and recurrent laryngeal nerve injury in patients undergoing total thyroidectomy (since there is an operation on both sides of the neck). Proponents of total thyroidectomy (more aggressive surgery) site several large studies that show that in experienced hands the incidence of recurrent nerve injury and permanent hypoparathyroidism are quite low (about 2%). More importantly, these studies show that patients with total thyroidectomy followed by radioiodine therapy and thyroid suppression, have a significantly lower recurrence rate and lower mortality when tumors are greater than 1.0 cm. One must remember that it is also desirable to reduce the amount of normal gland tissue that will take up radioiodine.

It also must be kept in mind that frozen section (the rapid way that the tumor is examined under the microscope for characteristics of cancer) may be unreliable in making definitive diagnosis of follicular cancer at the time of surgery. This problem is not seen with other types of thyroid cancer.

Based on the these studies and the above natural history and epidemiology of follicular carcinoma, the following is a typical plan: Follicular carcinomas that are well circumscribed, isolated, minimally invasive, and less than 1cm in a young patient (< 40) may be treated with hemithyroidectomy and isthmusthectomy. All others should probably be treated with total thyroidectomy and removal of any enlarged lymph nodes in the central or lateral neck areas. More detailed information on the different thyroid operations are included on another "Surgical Options" page.

Thyroid cells are unique in that they have the cellular mechanism to absorb iodine. The iodine is used by thyroid cells to make thyroid hormone. No other cell in the body can absorb or concentrate iodine. Physicians can take advantage of this fact and give radioactive iodine to patients with thyroid cancer. There are several types of radioactive iodine, with one type being toxic to cells. Follicular cancer cells absorb iodine (although to a lesser degree in older patients) and therefore they can be targeted for death by giving the toxic isotope (I-131). Once again, not everybody with follicular thyroid cancer needs this therapy, but those with larger tumors, spread to lymph nodes or other areas, tumors which appear aggressive microscopically, tumors which invade blood vessels within the thyroid, and older patients may benefit from this therapy. This is extremely individualized and no recommendations are being made here or elsewhere on this web site...too many vaimmunoassaybles are involved. But, this is an extremely effective type of "chemotherapy" will few potential down-sides (no hair loss, nausea, weight loss, etc.).

Uptake is enhanced by high TSH levels; thus patients should be off of thyroid replacement and on a low iodine diet for at least one to two weeks prior to therapy. It is usually given 6 weeks post surgery (this is vaimmunoassayble) can be repeated every 6 months if necessary (within certain dose limits).

Regardless of whether a patient has just one thyroid lobe and the isthmus removed, or the entire thyroid gland removed, most experts agree they should be placed on thyroid hormone for the rest of their lives. This is to replace the hormone in those who have no thyroid left, and to suppress further growth of the gland in those with some tissue left in the neck. There is good evidence that follicular carcinoma (like papillary cancer) responds to thyroid stimulating hormone (TSH) secreted by the pituitary, therefore, exogenous thyroid hormone is given which results in decreased TSH levels and a lower impetus for any remaining cancer cells to grow. Recurrence and mortality rates have been shown to be lower in patients receiving suppression.

In addition to the usual cancer follow up, patients should receive a yearly chest x-ray as well as thyroglobulin levels. Thyroglobulin is not useful as a screen for initial diagnosis of thyroid cancer but is quite useful in follow up of well differentiated carcinoma (if a total thyroidectomy has been performed). A high serum thyroglobulin level that had previously been low following total thyroidectomy especially if gradually increased with TSH stimulation is virtually indicative of recurrence. A value of greater than 10 ng/ml is often associated with recurrence even if an iodine scan is negative.

This page includes more advanced information on a specific type of thyroid cancer. . . Medullary Thyroid Cancer. Please read our Introduction to Thyroid Cancer page first which gives a general overview of all types of thyroid cancer since it will make this page easier to understand.

Medullary tumors are the third most common of all thyroid cancers (about 5 to 8 percent). Unlike papillary and follicular thyroid cancers which arise from thyroid hormone producing cells, medullary cancer of the thyroid originates from the parafollicular cells (also called C cells) of the thyroid. These C cells make a different hormone called calcitonin (thus their name) which has nothing to do with the control of metabolism the way thyroid hormone does. As you will see below, the production of this hormone can be measured after an operation to determine if the cancer is still present, and if it is growing. This cancer has a much lower cure rate than does the "well differentiated" thyroid cancers (papillary and follicular), but cure rates are higher than they are for anaplastic thyroid cancer. Overall 10 year survival rates are 90% when all the disease is confined to the thyroid gland, 70% with spread to cervical lymph nodes, and 20% when spread to distant sites is present.

Occurs in 4 clinical settings (see below), can be associated with other endocrine tumors

Females more common than males (except for inherited cancers)

Regional metastases (spread to neck lymph nodes) occurs early in the course of the disease

Spread to distant organs (metastasis) occurs late and can be to the liver, bone, brain, and adrenal medulla

Not associated with radiation exposure

Usually originates in the upper central lobe of the thyroid

Poor prognostic factors include age >50, male, distant spread (metastases), and MEN II-B

Residual disease (following surgery) or recurrence can be detected by measuring calcitonin

In contrast to papillary and follicular cancers, little controversy exits when discussing the management of medullary thyroid cancer. After assessment and treatment of associated endocrine conditions (such as pheochromocytomas if present) by an endocrinologist, all patients should receive total thyroidectomy, a complete central neck dissection (removal of all lymph nodes and fatty tissues in the central area of the neck), and removal of all lymph nodes and surrounding fatty tissues within the side of the neck which harbored the tumor. A diagram of thyroid operations are covered in greater detail (with drawings) on another "surgical options" page.

Although thyroid cells have the cellular mechanism to absorb iodine (see papillary cancer page), medullary thyroid cancer does not arise from this type of thyroid cell. Therefore, radioactive iodine therapy is not useful for the treatment of medullary thyroid cancer. Similarly, if medullary cancer spreads to distant sites, it cannot be found by iodine scanning the way that distant spread from papillary or follicular cancer can.

In addition to the usual cancer follow up, patients should receive a yearly chest x-ray as well as calcitonin levels Serum calcitonin is very useful in follow up of medullary thyroid cancer because no other cells of the body make this hormone. A high serum calcitonin level that had previously been low following total thyroidectomy is indicative of recurrence. Under the best circumstances, surgery will remove all of the thyroid and all lymph nodes in the neck which harbor metastatic spread. In this case, post operative calcitonin levels will go to zero. This is often not the case, and calcitonin levels remain elevated, but less than pre-operatively. These levels should still be checked every 6 months, and when they begin to rise, a more diligent examination is in order to find the source.

This page includes more advanced information on a specific type of thyroid cancer. . . Anaplastic Thyroid Cancer. Please read our Introduction to Thyroid Cancer page first which gives a general overview of all types of thyroid cancer since it will make this page easier to understand.

Anaplastic tumors are the least common (about 2-3%) and most deadly of all thyroid cancers. This cancer has a very low cure rate with the very best treatments allowing only 10 % of patients to be alive 3 years after it is diagnosed. They often arise within a more differentiated thyroid cancer or even within a goiter. Like papillary cancer, anaplastic cancer may arise many years (~20) following radiation exposure. Cervical metastasis (spread to lymph nodes in the neck) are present in the vast majority (over 90%) of cases at the time of diagnosis. The presence of lymph node metastasis in these cervical areas causes a higher recurrence rate and is predictive of a high mortality rate. The most common way this cancer becomes evident is by the patient or his/her family member noticing a growing neck mass.

Anaplastic cancers invade adjacent structures and metastasize extensively to cervical lymph nodes and distant organs such as lung and bone. Tracheal invasion is present in 25% at the time of presentation. Spread (metastasis) to the lung is present in 50% of patients at the time of diagnosis. Most of these cancers are so aggressively attached to vital neck structures that they are inoperable at the time of diagnosis. Even with aggressive therapy protocols such as hyperfractionated radiation therapy, chemotherapy, and surgery, survival at 3 years is less than 10%.

Peak onset age 65 and older

Very rare in young patients

Males more common than females by 2 to 1 ratio

Typically presents as rapidly growing neck mass

Can occur many years after radiation exposure

Spread to lymph nodes of the neck present in more than 90% of cases

Distant spread (to lungs or bones) is very common even when first diagnosed

Overall cure rate very low

The major problem with anaplastic thyroid cancer, is that it is usually too aggressive and invasive when it is diagnosed. Therefore, only a small portion of patients can undergo surgical resection of the cancer in hopes of cure. For those patients which are diagnosed at an earlier stage, total thyroidectomy is necessary. Many patients, especially those who have advanced cancer and cannot undergo surgical resection, will benefit from external-beam radiation (this is different from radioactive iodine). Some chemotherapy treatments may also be beneficial to patients with anaplastic thyroid cancer.

Which operation is performed on a thyroid gland depends upon 2 major factors. The first is the thyroid disease present which is necessitating the operation. The second is the anatomy of the thyroid gland itself as is illustrated below.

Thyroid has two lobes and an isthmus.

If a dominant solitary nodule is present in a single lobe, then removal of that lobe is the preferred operation (if an operation is even warranted). If a massive goiter is compressing the trachea and esophagus, the the goal of surgery will be to remove the mass and usually this means a sub-total or total thyroidectomy (occasionally a lobectomy will suffice). If a hot nodule is producing too much hormone resulting in hyperthyroidism, then removal of the lobe which harbors the hot nodule is all that is needed.

Most surgeons and endocrinologists recommend total or near total thyroidectomy in virtually all cases of thyroid carcinoma. In some patients with papillary carcinomas of small size, a less aggressive approach may be taken (lobectomy with removal of the isthmus). A lymph node dissection within the anterior and lateral neck is indicated in patients with well differentiated (papillary or follicular) thyroid cancer if the lymph nodes can be palpated. This is a more extensive operation than is needed in the majority of thyroid cancer patients. All patients with medullary carcinoma of the thyroid require total thyroidectomy and aggressive lymph node dissection.

Partial Thyroid Lobectomy. This operation is not performed very often because there are not many conditions which will allow this limited approach. Additionally, a benign lesion must be ideally located in the upper or lower portion of one lobe for this operation to be a choice. One example is shown on our hyperthyroid treatments page.

Thyroid Lobectomy. This is typically the "smallest" operation performed on the thyroid gland. It is performed for solitary dominant nodules which are worrisome for cancer or those which are indeterminate following fine needle biopsy. Also appropimmunoassayte for follicular adenomas, solitary hot or cold nodules, or goiters which are isolated to one lobe (not common).

Thyroid Lobectomy with Isthmusectomy. This simply means removal of a thyroid lobe and the isthmus (the part that connects the two lobes). This removes more thyroid tissue than a simple lobectomy, and is used when a larger margin of tissue is needed to assure that the "problem" has been removed. Appropimmunoassayte for those indications listed under thyroid lobectomy as well as for Hurthle cell tumors, and some very small and non-aggressive thyroid cancers.

Subtotal Thyroidectomy. Just as the name implies, this operation removes all the "problem" side of the gland as well as the isthmus and the majority of the opposite lobe. This operation is typical for small, non-aggressive thyroid cancers. Also a common operation for goiters which are causing problems in the neck or even those which extend into the chest (substernal goiters).

Total Thyroidectomy. This operation is designed to remove all of the thyroid gland. It is the operation of choice for all thyroid cancers which are not small and non-aggressive in young patients. Many (most?) surgeons prefer this complete removal of thyroid tissue for all thyroid cancers regardless of the type.

The standard neck incision is made typically measuring about 4-5 inches in length although many endocrine surgeons are now performing this operation through an incision as small as 3 inches in thin patients. This incision is made in the lower part of the central neck and usually heals very well. It is almost unheard of to have an infection or other problem with this wound. The surgeon will then typically remove the part of the thyroid which contains the "problem". As mentioned above, for thyroid cancer, this will usually entail all of the thyroid lobe which harbors the malignancy, the isthmus, and a vaimmunoassayble amount of the opposite lobe (ranging from 0 to 100% depending on the size and aggressive nature of the cancer, the cancer type, and the experience of the surgeon). The surgeon must be careful of the recurrent laryngeal nerves which are very close to the back side of the thyroid and are responsible for movement of the vocal cords. Damage to this nerve will cause hoarseness of the voice which is usually temporary but can be permanent. This is an uncommon complication (about 1 to 2 percent), but it gets lots of press because it is serious. The surgeon must also be careful to identify the parathyroid glands so their blood supply can be maintained. Another potential complication of thyroid surgery (although VERY RARE) is hypoparathyroidism which is due to damage to all four parathyroid glands. Usually the only thyroid operations which have even a slight chance of this complication is the total or subtotal thyroidectomy. Although these complications can be serious, their risk should not be the sole determinant of whether or not to undergo surgery.

The relationship of the thyroid gland to the voice box and parathyroid glands can be seen here quite clearly. Remember that they share the same blood supply, so the surgeon must take care to preserve the parathyroid artery and vein while ligating the vessels to the thyroid gland itself. This is usually not a problem, but sometimes it is not possible to save them all. In this case, the surgeon will usually implant the parathyroid gland into a muscle in the neck. The parathyroid will grow there and function normally...its not a big deal, and you'll never know the difference.

Often formal surgery is not needed to determine if a thyroid mass is cancerous. Because these masses can often be felt, a physician can stick a small needle into it to sample cells for malignancy. This is called Fine Needle Aspiration Biopsy (FNA) and is covered in detail on another page which also covers the potential of thyroid masses to be malignant in much greater detail.

Thyroid Goiter

The term nontoxic goiter refers to enlargement of the thyroid which is not associated with overproduction of thyroid hormone or malignancy. The thyroid can become very large so that it can easily be seen as a mass in the neck. This picture depicts the outline of a normal size thyroid in black and the greatly enlarged goiter in pink. There are a number of factors which may cause the thyroid to become enlarged. A diet deficient in iodine can cause a goiter but this is rarely the cause because of the readily available iodine in our diets. A more common cause of goiter in America is an increase in thyroid stimulating hormone (TSH) in response to a defect in normal hormone synthesis within the thyroid gland. The thyroid stimulating hormone comes from the pituitary and causes the thyroid to enlarge. This enlargement usually takes many years to become manifest.

Large goiter in the neck.

This picture depicts the typical appearance of a goiter in a middle aged woman. Note how her entire neck looks swollen because of the large thyroid. This mass will compress the trachea (windpipe) and esophagus (swallowing tube) leading to symptoms such as coughing, waking up from sleep feeling like you cant breath, and the sensation that food is getting stuck in the upper throat. Once a goiter gets this big, surgical removal is the only means to relieve the symptoms. Yes, sometimes they can get a lot bigger than this!

Most small to moderate sized goiters can be treated by providing thyroid hormone in the form of a pill. By supplying thyroid hormone in this fashion, the pituitary will make less TSH which should result in stabilization in size of the gland. This technique often will not cause the size of the goiter to decrease but will usually keep it from growing any larger. Patients who do not respond to thyroid hormone therapy are often referred for surgery if it continues to grow.

Trachea compressed by large goiter

A more common indication for surgical removal of an enlarged thyroid [goiter] is to remove those glands which are enlarged enough to cause compression on other structures in the neck such as the trachea and esophagus. These patients will typically complain of a cough, a slight change in voice, or nighttime choking episodes because of the way that the gland compresses the trachea while sleeping. This X-ray shows how an enlarged right lobe of the thyroid has moved the trachea to the patient's left. The trachea (outlined in light yellow) should be straight from the mouth down to the lungs, but in this patient it is compressed and displaced far to the left. The enlarged gland can even compress the blood vessels of the neck which are also an indication for its removal. More about this on our page examining sub-sternal thyroids.

As always, suspicion of malignancy in an enlarged thyroid is an indication for removal of the thyroid. There is often a dominant nodule within a multinodular goiter which can cause concern for cancer. It should be remembered that the incidence of malignancy within a multinodular goiter is usually significantly less than 5%. If the nodule is cold on thyroid scanning, then it may be slightly higher than this. For the vast majority of patients, surgical removal of a goiter for fear of cancer is not warranted.

Another reason (although not a very common one) to remove a goiter is for cosmetic reasons. Often a goiter gets large enough that it can be seen as a mass in the neck. When other people begin to notice the mass, it is usually big enough to begin causing compression of other vital neck structures...but not always. Sometimes the large goiter causes no symptoms other than being a cosmetic problem. Realizing of course, if its big enough to be seen by your neighbors, something needs to be done...medications or surgery or it will most likely continue to get bigger.

Sub-Sternal Thyroids and Goiters

Please read the page on Thyroid Goiters before you read this page. It will make it easier to understand.

The normal thyroid gland resides in the neck, with both lobes wrapping gently around the trachea (breathing tube). When thyroids get enlarged (called a goiter), they can grow a number of different directions. Usually, they will grow within the neck as shown in the picture of the woman on our goiter page. When this is the case, they are seen as a large mass in the neck. Since they grow slowly, taking a number of years to obtain their large size, many people aren't aware of just how large the thyroid has become.

Less commonly, a thyroid will grow downward rather than up and out within the neck. When this happens, the thyroid will grow down the trachea into the chest. This can become an even bigger problem since the chest is surrounded by a very rigid bone structure (the chest cavity). The top of the chest cavity is made up of the spinal column in the back, the first and second ribs on the sides, and the collar bones (clavicles) and breast bone (sternum) in the front. When a thyroid gets enlarged within this rigid bony structure, it will compress those structures which are soft such as the trachea, lungs, and blood vessels (the bones will not give way). This is what makes sub-sternal thyroids a special case which deserve special attention.
Trachea compressed by large goiter

This chest x-ray shows a sub-sternal thyroid which is compressing and displacing the trachea to the patient's left The trachea (outlined in light yellow) should run straight from the mouth/nose down to the lungs rather than being curved like it is in this picture. This is not as un-common as you may think.

CT scan of sub-sternal goiter.

The picture on the left shows a CT scan (also called CAT scan) from the same patient. The CT produces a picture as if the patient was cut in half so we can see inside. The patient is lying on her back and this is a cut through the upper chest just above the heart. The two large black areas are the lungs and are labeled with an "L". The sternum (breast bone) is the white curved structure near the top of the picture. The trachea (outlined in red) should be in the midline, but is pushed to the left and compressed by a large amount of thyroid tissue (outlined in yellow) which is extending down into the chest. You can see that some of the space which would normally be taken up by the right lung is replaced with the mass (loss of lung volume). Remember, x-rays usually show the patient's right on the left of the picture as if we were looking at the patient. Compression of the trachea and esophagus (hard to see on x-rays) by the large thyroid are what gives the symptoms listed below. This can happen with a goiter which is completely in the neck, or it can happen if the goiter grows down into the chest (remember, it doesn't belong in the chest!).

This CT scan shows a similar problem. The thyroid goiter (outlined in yellow) has grown into the chest below the sternum. The trachea (outlined in red) is displaced to the patient's right side (shown on CT scans on the left of the picture). Remember, the trachea is supposed to be in the middle of the chest and the thyroid should not extend into the chest at all. This patient has a hard time swallowing breads and meats, and she feels like she is suffocating when she lies on her back.

It is a misconception that all sub-sternal thyroids require that the sternum be split to allow it to be removed. In fact, this is extremely rare. Essentially all sub-sternal thyroids can be removed through a conventional thyroid neck incision. It must be remembered that the blood supply to the thyroid is from two separate sources both of which arise in the neck (and not the chest). That means that the blood supply can be cut off from above without undue fear of intra-operative bleeding. After the patient is put to sleep under anesthesia, his/her neck can be extended fairly far backward which helps pull the thyroid up from the chest making it easier to remove. Remember, even though these goiters can extend WAY down into the chest, it is very uncommon for a sternal splitting operation to be necessary.

The most common thyroid disorder occurring around or during pregnancy is thyroid hormone deficiency, or hypothyroidism. The details of hypothyroidism are covered on several other pages on our site, so only those factors pertaining to pregnancy are discussed here. Hypothyroidism can cause a variety of changes in a woman's menstrual periods: irregularity, heavy periods, or loss of periods. When hypothyroidism is severe, it can reduce a woman's chances of becoming pregnant. Checking thyroid gland function with a simple blood test is an important part of evaluating a woman who has trouble becoming pregnant. If detected, an underactive thyroid gland can be easily treated with thyroid hormone replacement therapy. If thyroid blood tests are normal, however, treating an infertile woman with thyroid hormones will not help at all, and may cause other problems.

Because some of the symptoms of hypothyroidism such as tiredness and weight gain are already quite common in pregnant women, it is often overlooked and not considered as a possible cause of these symptoms. Blood tests, particularly measuring the TSH level, can determine whether a pregnant woman's problems are due to hypothyroidism or not.

Since thyroid medications (particularly Levothyroxine) are essentially identical to the thyroid hormone made by the normal thyroid gland, a woman with an underactive thyroid gland can feel confident that it is perfectly safe to take thyroid hormone medication during pregnancy. There are no side effects for the mother or the baby as long as the proper dose is used. In the case where hypothyroidism in the mother is NOT detected, the thyroid will still develop normally in the baby.

Women with previously treated hypothyroidism should be aware that their dose of medication may have to be increased during pregnancy. They should contact their doctor, who should check their blood level of TSH periodically throughout pregnancy to see if their medication dose needs adjustment. Thyroid function tests should continue to be reviewed every 2-3 months throughout the pregnancy. After delivery, the thyroxine dose should be returned to the pre-pregnancy dose and thyroid function tests reviewed two months later.

Hyperthyroidism refers to the signs and symptoms which are due to the production of too much thyroid hormone. An overactive thyroid gland (hyperthyroidism) often has its onset in younger women. Because a woman may think that feeling warm, having a hard or fast heartbeats, nervousness, trouble sleeping, or nausea with weight loss are just parts of being pregnant, the symptoms and signs of this condition may be overlooked during pregnancy.

In women who are not pregnant, hyperthyroidism can affect menstrual periods, making them irregular, lighter, or disappear altogether. It may be harder for hyperthyroid women to become pregnant, and they are more likely to have miscarimmunoassayges. If a woman with infertility or repeated miscarimmunoassayges has symptoms of hyperthyroidism, it is important to rule out this condition with thyroid blood tests. It is very important that hyperthyroidism be controlled in pregnant women since the risks of miscarimmunoassayge or birth defects are much higher without therapy. Fortunately, there are effective treatments available. Antithyroid medications cut down the thyroid gland's overproduction of hormones and are reviewed on another page on this site. When taken faithfully, they control hyperthyroidism within a few weeks. In pregnant women thyroid experts consider propylthiouracil (PTU) the safest drug. Because PTU can also affect the baby's thyroid gland, it is very important that pregnant women be monitored closely with examinations and blood tests so that the PTU dose can be adjusted. In rare cases when a pregnant woman cannot take PTU for some reason (allergy or other side effects), surgery to remove the thyroid gland is the only alternative and should be undertaken prior to or even during the pregnancy if necessary. Although radioactive iodine is a very effective treatment for other patients with hyperthyroidism, it should never be given during pregnancy because the baby's thyroid gland could be damaged.

Because treating hyperthyroidism during pregnancy can be a bit tricky, it is usually best for women who plan to have children in the near future to have their thyroid condition permanently cured. Antithyroid medications alone may not be the best approach in these cases because hyperthyroidism often returns when medications is stopped. Radioactive iodine is the most widely recommended permanent treatment with surgical removal being the second (but widely used) choice. It is concentrated by thyroid cells and damages them with little radiation to the rest of the body. This is why it cannot be given to a pregnant woman, since the radioactive iodine could cross the placenta and destroy normal thyroid cells in the baby. The only common side effect of radioactive iodine treatment is underactivity of the thyroid gland, which occurs because too many thyroid cells were destroyed. This can be easily and safely treated with levothyroxine. There is no evidence that radioactive iodine treatment of hyperthyroidism interferes with a woman's future chances of becoming pregnant and delivering a healthy baby. For more information on the treatment options of hyperthyroidism see our page on this topic.

One of every twenty women develop thyroid inflammation within a few months after delivery of their baby, a condition called postpartum thyroiditis. This form of thyroid inflammation is painless and causes little or no gland enlargement. However, the condition interferes with the gland's production of thyroid hormones. Thyroid hormone may leak out of the inflamed gland in large amounts, causing hyperthyroidism that lasts for several weeks. Later on, the injured gland may not be able to make enough thyroid hormone, resulting in temporary hypothyroidism. Symptoms of hyperthyroidism and hypothyroidism may not be recognized when they occur in a new mother. They may be simply attributed to lack of sleep, nervousness, or depression.

Hyperthyroidism

Fatigue

Insomnia

Nervousness

Irritability

Hypothyroidism

Fatigue

Depression

Easily upset

Trouble losing weight

Postpartum thyroiditis goes away on its own after one to four months. While it is active, however, women often benefit from treatment for their thyroid hormone excess or deficiency. Some of the symptoms caused by too much thyroid hormone, such as tremor or palpitations, can be improved promptly by medications called beta-blockers(e.g., propranolol). Antithyroid drugs, radioactive iodine, and surgery do not need to be considered because this form of hyperthyroidism is only temporary. If thyroid hormone deficiency develops, it can be treated for one to six months with levothyroxine. Women who have had an episode of postpartum thyroiditis are very likely to develop the problem again after future pregnancies. Although each episode usually resolves completely, one out of four women with postpartum thyroiditis goes on to develop a permanently underactive thyroid gland in future. Of course, levothyroxine fully corrects their thyroid hormone deficiency, and when used in the correct dose, can be safely taken without side effects or complications.

Rarely, a baby may be born without a thyroid gland. This birth defect is not caused by thyroid problems in the mother. If an infant's hypothyroidism is not recognized and treated promptly, he/she will not develop normally. Therefore, all newborn babies in the United States routinely have a blood test to be sure that hypothyroidism is diagnosed and treated. Most thyroid medications will have no effect on the baby. The exception to this generality is the administration of radioactive iodine to the mother during pregnancy. Radioactive iodine can cross the placenta and it can destroy thyroid cells in the fetus.