All Thyroid Tests

Thyroid Testing and health information

Ulta Lab Tests provides the ten key lab tests to diagnose, monitor, and manage hypothyroidism and hyperthyroidism. 

Two primary conditions may require a thyroid test: hypothyroidism and hyperthyroidism. Hypothyroidism encompasses conditions in which your thyroid isn't producing enough T3 and T4. Hyperthyroidism is the term for conditions where your body produces too much thyroid hormone.  

Hypothyroidism, a condition when your thyroid isn't making enough hormone, may be caused by Hashimoto's thyroiditis, secondary hypothyroidism (a failure of the pituitary gland), or some inflammatory conditions. You may notice that you're tired all the time, have trouble remembering things, gain weight, and feel cold all the time. You may also have dry skin, constipation, and general body weakness.

When your thyroid makes too much hormone, hyperthyroidism is often the result of a condition called Grave's disease. If you have hyperthyroidism, you may notice that you have trouble sleeping, you're nervous or irritable all the time, or you get hot easily. You may also have frequent diarrhea, trembling hands, a rapid heartbeat, and muscle weakness.


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This article will cover the thyroid biomarkers. This will include the thyroid-stimulating hormone, also known as TSH. We’re also going to look at T3 and T4, both free and total in each case. We’ll also cover reverse T3 and investigate a new ratio, being the free/reverse T3 ratio. Also, we’re going to look at a few older markers, too, including the free thyroid index called T7. Then, we’ll move on to T3 uptake and move on to two of the most essential antibodies. Finally, we’ll investigate antithyroglobulin antibodies, thyroid peroxidase, and anti-TPO. 

In terms of TSH, it’s useful for many different reasons. First, we can use it for both the determination of hypothyroidism as well as the potential differentiation of it. It’s also effective for both hyperactive thyroid and the certainly more pathological variant of hyperthyroidism. It is, in fact, one of the more sensitive possible tests involved in blood chemistry screening when looking for primary hypothyroidism, but not as much for thyroid conversion syndrome, which we’re going to cover later in our hyperthyroid section. In cases where TSH is normal, but there’s a clinical picture suggesting hypothyroidism, it’s advisable to investigate different factors, including conversions and the like. Regarding anterior pituitary hypothalamic function, a mildly different TSH shift is usually to be expected. 

In the end, the objective is to ascertain the specific reason for a thyroid-related issue. Here, the potential condition in play is the actual thyroid gland. It’s not always other systems. As a component of your broader thyroid screening panel, you should include TSH and possibly even a handful of different thyroid biomarkers which we’re going to cover. However, for our conversation about TSH, I’d like to talk a bit about what normal TSH levels should be. Some of you might be shocked to discover that historically speaking, the higher TSH range used to be 1 up to 9. However, it’s now actually down to 4.5, which means most American labs now use a typical TSH reference range that goes from 0.4 up to 4.5.  

At this time, notable experts are suggesting the upper range be lowered down to 3, if not 2, or even lower. That’s much closer to what a handful of functional practitioners are advocating for, although in the end, many of them prefer 3 as the upper range. Again, most American labs run their typical TSH range from 0.4 up to 4.5; however, analysis done by many researchers suggest that even this range of reference isn’t especially useful. You can expect a 1.5 mean TSH level for those individuals who lack thyroid antibodies present or are not diagnosed with thyroid disease. Reviews conducted of many published findings regarding TSH levels shows that a reading higher than 2 might indicate negative health issues that are associated with a lack of thyroid hormone output. One study highlighted that individuals that have TSH levels greater than 2 also have higher odds over the next two decades of developing the overt hypothyroid disease. Other studies point out that TSH values above 1.9 are indicative of abnormal pathologies within the thyroid; in particular, these can be autoimmune attacks targeting the actual thyroid gland, and these can lead to a substantial impairment. One disturbing study pointed out how TSH values greater than 4 mean a higher risk of heart disease is prevalent, even when other established factors were corrected for. When you take all this into account, it means that the optimal physiological TSH value is probably in the range of 1.3 up to 3. Utilizing other thyroid tests with this range gives us the power to analyze the thyroid better than ever before. 

That means that the optimal range for thyroids, thanks to functional practitioners, is from 1.3 up to 3. The next logical question is what this means at a clinical level. Given how high TSH levels are often related to primary hypothyroidism, it really implies that any issues are with the actual thyroid gland. In such circumstances, TSH levels are going to be raised. Hypothyroidism is a very common condition, and unfortunately, also frequently one that escapes diagnosis. What we’re focusing on right now is the relationship of TSH to primary hypothyroidism. Low levels here could indicate anything from hyperactive thyroid up to hyperthyroidism. Levels might also be low as a result of secondary hypothyroidism, an anterior pituitary dysfunction, as well as in the case of tertiary hypothyroidism, a hypothalamic dysfunction. We cover those in our hypothyroidism section. You might even witness low TSH levels in a case we have termed heavy metal body burden. The hormone that the thyroid releases is T4, and it’s primarily bound to binding proteins like the thyroxine-binding globulin, also known as TBG. Only approximately 0.03 up to 0.05 of this is in a free form, which is why we measure both free and total, which is free and bound. At what times should you be mindful of this test? It’s frequently used to specifically rule out both hypothyroidism and hyperthyroidism both. This can happen because the hormone gets secreted directly out of the gland in such conditions, which are primarily glandular in nature. T4 is also useful in possibly detecting and/or ruling out things like autoimmune thyroiditis, primary hypothyroidism, hyperthyroid states, and Hashimoto’s and Graves’ diseases. 

It’s also helpful in maintaining proper thyroid hormone dosage levels when treating hypothyroidism. In terms of reference ranges, a common United States lab range might go from 4.5 up to 12 mcg for each deciliter. An optimal range that you want to see is anywhere from 6 up to 11.9 mcg/deciliter. You can also do a measurement of free unbound T4, which is measured in nanograms per deciliter. Functional practitioners prefer seeing from 1 up to 1.5 nanograms in each deciliter. The question now is when you’d witness elevated levels of total or free T4? 

You’ll witness elevated T4 levels in cases of hyperthyroidism, hyperactive thyroid, and patients currently on thyroxine medication or supplementation. That might be Armour Thyroid, Synthroid, or other kinds of thyroid drugs and/or supplementation. These can result in elevated total and free levels. Low levels are more likely to be witnessed in iodine deficiency, primary hypothyroidism, and secondary hypothyroidism. Our article on hypothyroidism has more information regarding all three of these. 

Moving on to T3, keep in mind that this is a thyroid molecule that has an iodine molecule removed via tyrosyl residues. That means that ‘T3’ is letting us know that only three iodines are present. T3 is widely considered to be one of the more metabolically active members of the thyroid hormone family. Estimates suggest that it is roughly four or five times more active when metabolically compared to T4. 

The thyroid produces some of it, but most of it, usually 80 up to 85 percent, is made outside of the thyroid. This happens mostly by peripheral tissues like the kidneys and liver converting T4. T3 is an enzyme-dependent on selenium known as five-prime deiodinase. 

When should you test for this? When you’re trying to diagnose thyroid disorders. Clinical values for total T3 in lab testing in the United States range anywhere from 76 up to 181 nanograms for each deciliter. The optimal range for functional practitioners for total T3 is a bit narrower, from 90 up to 168 nanograms for each deciliter. In metric, it’s 1.4 up to 2.6 nanomoles for each liter. Free T3 levels in the United States are measured using two distinct units. 

One is picograms per deciliter, and the other is nanograms per deciliter. Based on what lab you use; you’ll discover that these values are going to be different by as much of a factor of 100. Some labs use the nanograms per deciliter. If your lab gives you picograms per deciliter, then you just divide the number by 100 to get nanograms per deciliter. The standard range for most labs is anywhere from 2.3 up to 4.2 nanograms for each deciliter. The optimal range for functional practitioners is tighter, running from 3 up to 3.25 nanograms for each deciliter, which of course, is 300 up to 235 picograms for each deciliter. 

So, what comes from all of this? As with T4, elevated T3 levels might be present of both hyperthyroidism and hyperactive thyroid. Higher total and free T3 levels can happen in certain instances of iodine insufficiency. Low T3 levels are witnessed in primary hypothyroidism. In a condition known as thyroid conversion syndrome, T4 can be normal even when T3 is very low. This can also happen in the event of Euthyroid sick syndrome, which looks very similar but has a different kind of pathophysiology. That’s covered in our hypothyroid article. You might also see cases of total and free T3, both being specifically low in selenium, to the point of deficiency. Remember that the enzyme five-prime deiodinase is selenium-dependent and crucial for iodine removal, for the five prime spots in the first tyrosyl ring. If there is a selenium deficiency, that enzyme might not be fully functional. 

Reverse T3 is a metabolically, inactive thyroid hormone. As with T3, the thyroid makes small amounts on its own. However, approximately 95 percent of reverse T3 production comes from T4 peripheral conversion. Five prime deiodinases aren’t the enzyme responsible in this case. It would be five deiodinases since the iodine is being removed from the second tyrosyl residue instead of the first. At this time, it’s not assumed that this one is selenium dependent. 

At what times would you do a reverse T3? It’s useful if you want to figure out the reason behind a low free or total T3, as witnessed in thyroid conversion syndrome. Reverse T ranges for standard labs are typically from 8 up to 25 nanograms for each deciliter. Functional practitioners, on the other hand, prefer an optimum range of 10 up to 25 nanograms for each deciliter. In metric, that is 0.15 up to 0.38 nanomoles in each liter. 

So, what factors or known to related to higher levels of reverse T3? For starters, it’s highly correlated to diabetes, interleukin six, interferon two, tissue necrosis factor-alpha, and elevated levels of cytokine. Fasting can result in elevated T3 levels, as can an increase in free radicals, heavy metals, oxidative stress, and increased catecholamines. In some cases, it can be prolonged stress or illness, and it can also be noradrenaline, adrenaline, epinephrine, and norepinephrine. Stress might be one of the more crucial factors. Decreases in reverse T3 aren’t considered clinically significant. In terms of T3 uptake, the name can be misleading, since it has nothing at all to do with T3 levels. Rather, it’s a somewhat roundabout way of measuring unsaturated binding sites on the various thyroxine-binding proteins, of which there are three. They are thyroid-binding globulin, albumin, and transthyretin. This test is best only ordered as a component of a thyroid panel that includes T4. In a short while, you’ll also see how it’s useful in calculating a free thyroxine index. T3 uptake is contingent upon how many binding sites there are on a thyroxine-binding protein. Unlike albumin or transthyretin, TBG only has one binding site for both T3 or T4, meaning that any changes in the volume of thyroid-binding proteins and any related binding sites will impact T3 uptake. TBG abnormalities can be drug-induced, congenital, or even the result of illnesses not related to the thyroid, such as kidney or liver disease. Any circumstances which result in a decrease of TBGs mean that T3 uptake goes up, and the reverse also holds true. When should you be mindful of this test? It needs to happen as a component of a total thyroid panel, but if there isn’t any T4, then it’s not useful. By itself, it’s also not helpful. However, this test can rule out lab errors as a potential cause behind a T4 increase. If T3 and T4 update levels are both increased, then that can confirm a genuine T4 increase. 

A typical lab range for T3 uptake is from 22 up to 35 percent. T3 uptake is, of course, a percentage, and functional practitioners should consider 27 up to 35 percent as an optimal range. Things that can elevate it would include thyroid hormone replacement, hyperthyroidism, and hyperactive thyroid. In contrast, low levels might be witnessed in iodine deficiency, selenium deficiency, and hypothyroidism. 

Free thyroxine index is the next Thyroid Biomarkers I want to cover. It’s alternatively known as T7 or just FTI. Many blood tests involve this calculated measurement. The reason why the FTI and T3 uptake tests are on panels is that it used to be harder to measure the specific T3 and T4 levels, particularly of the free variants. Modern measurement techniques are far more sensitive, simpler, and more cost-effective. However, it’s still useful to know about such tests and be mindful of them. 

The FTI determines the volume of available active thyroid hormone. This calculated measurement comes from the multiplication of total T4 with the T3 uptake, meaning it was a means of estimating the amount of available free T4. It’s widely considered reliable for indicating thyroid condition when there are presently abnormalities with the plasma protein binding. The clinical lab range is the same as the optimal range for once, which is 1.7 up to 4.6. You might witness this being low in cases of hypothyroidism, but high in both hyperthyroidism and hyperactive thyroid. 

Our next Thyroid Biomarkers to cover is the free T3/reverse T3 ratio. This ratio is useful in seeing what’s going on down at the tissue level since it is useful in ascertaining the efficiency of thyroid conversion of T4 into free or active T3. Use it as a calculation to see when active thyroid conversion is happening or not. 

There are some requirements. Free T3 must be in picograms per deciliter, which is in the hundreds. So, if you have picograms per milliliter as your value, you just multiply it by a hundred. Reverse T3 must be listed in nanograms for each deciliter, the normal US unit. 

Are you curious why you would ever use this? The answer is ascertaining whether there are complications with T4 to T3 thyroid hormone conversion. A great number of practitioners agree that it’s good to see ratios higher than 20. On the other hand, if there are elevated levels of free T3, but why would this happen? In many cases, patients might be taking T3 supplementation, which can result in false free T3 elevations. When that happens, the ratio might look a lot better than it is. 

Quite a few practitioners of functional wellness prefer seeing a ratio over 20. If both the reverse and free T3 values are in optimal status, then the ratio might help you get a feel for what’s going on down at the actual tissue level. At least that’s the case when the ratio is over 2, although 10 to 20 is better, and of course, being over 20 is best. Still, high levels aren’t always truly relevant. However, low levels can be a signal of there being thyroid conversion syndrome present. 

Regarding thyroid antibodies, we’re going to go over the two primary ones. One is the antithyroglobulin antibody, and the other is anti-TPO, otherwise known as thyroid peroxidase

Let’s start off with thyroid peroxidase first. Thyroid cells have this enzyme, and its role is attaching iodine molecules to tyrosyl resides. This makes T4, or thyroxine. Thyroid peroxidase antibody testing is a means of measuring the volume of bloodstream antibodies known to be attacking TPO enzymes located in thyroid cells. An elevated level of anti-TPO is commonly found in autoimmune thyroiditis conditions like Hashimoto’s. This is something we review in an article about hyperthyroid autoimmune thyroiditis. Now, for some background on the antithyroglobulin antibody. Thyroglobulin is a certain protein that thyroid gland follicular cells produce. This means that this protein is a precursor for T4, and even T3 to some degree. Thyroglobulin’s tyrosine residues undergo combination with iodine before the protein is eventually cleaved right into singular tyrosine residues. 

It’s thyroid peroxidase enzymes that go into action, putting iodine onto tyrosine residues. Every molecule of thyroglobulin protein has a normal range of 100 up to 120 tyrosine residues. Yet, eventually, a tiny percentage of these come into play. Some suggest that only about 20 of these tyrosine residues get iodinated by thyroid peroxidase inside the thyroid follicle. Keep in mind that every thyroid hormone molecule is, in fact, two different tyrosine residues, so there is some math involved at this point. For every molecule of thyroglobulin, we only wind up with 20 tyrosine residues. When those two are joined to come up with thyroxine, the result is that each molecule of thyroglobulin winds up, providing approximately 10 thyroid hormone molecules. Eventually, thyroglobulin antibodies are immune cells, and as such, they attack the thyroid’s thyroglobulin. 

At what time should you be mindful of all this? The answer is any time that you suspect there might be autoimmune thyroiditis going on. You need to run both these when there are any abnormalities of the thyroid suspected. This is even more true when there are elevated TSH levels. Doing this will be useful in differentiating between many different autoimmune conditions. You can differentiate between things like subacute thyroiditis versus Graves’ or Hashimoto’s disease. These are strongly rooted in antibody titers, which we reviewed in our article covering hyperthyroid and autoimmune thyroiditis. In our Quest values here, we can see from 0 up to 9 IUs/mL, with an optimal range of 0 up to 6. 

In terms of antithyroglobulin antibodies, the optimal and standard ranges are both zero to one. There are times that you might see elevated levels of anti-TPO antibodies. Three of them are thyroid cancer, Graves’ disease, and the early and late stages of Hashimoto’s thyroiditis. In these cases, low findings aren’t considered to be clinically relevant. 

TSH (Thyroid-Stimulating Hormone)

Test: TSH (Thyroid-stimulating Hormone)

Why have this test? 

This Thyroid-Stimulating Hormone is used to check for and diagnose disorders of the thyroid. It is also used to monitor the ongoing treatment of both hyperthyroidism and hypothyroidism.

When Should You be Tested?

Screening is commonly recommended for newborns. There is no medical consensus as to the adult age for screening or whether adult screening should be standard.

Treatment monitoring: As recommended by your medical provider

Other Situations:  If an individual has an enlarged thyroid and/or has experienced the symptoms of hypothyroidism or hyperthyroidism.

Required Sample Type: A sample of blood taken from a vein in the arm, or for infants, from pricking the heel.

Preparation for the Test: There is no specific preparation necessary. Some medications can interfere with the TSH testing. Let your medical providers know about any medications that you take. If you regularly take thyroid hormones to treat a disease of the thyroid, you should have your blood sample drawn before taking your hormone dose for the day.

What Does This Test Measure? 

Thyroid-stimulating hormone (TSH) is produced by the pituitary gland. This is a very small organ behind the sinus cavities and below the brain. TSH triggers the thyroid gland to release the thyroid hormones thyroxine (T4) and triiodothyronine (T3) into the bloodstream. These hormones regulate the rate at which the body consumes energy. This laboratory test measures the amount of TSH in the blood at a given time.

Thyroid-stimulating hormone, combined with TRH, which is released by the hypothalamus, make up the system that the body uses to keep consistent amounts of thyroid hormones in the bloodstream at all times. If these hormoneconcentrations drop, the pituitary gland increases the production of TSH.

Thyroid-stimulating hormone then stimulates production and release of significantly more T3 and T4 by the thyroid, which is a small gland at the base of the throat shaped like a butterfly. If all these organs are working correctly, the thyroid production turns itself on and off appropriately to keep the correct hormone levels in the bloodstream.

However, if the thyroid releases too much T3 and T4, the individual can suffer from the symptoms of hyperthyroidism like rapid heartbeat, weight loss, nervousness, trouble sleeping, and hand tremors. The most common cause of hyperthyroidism is Graves’ disease, which is a chronic autoimmune disease. Patients with this diagnosis deal with their bodies producing antibodies that behave as if they’re TSH, causing their bodies to create too much thyroid hormone. The pituitary may also produce too little TSH, causing very low levels in the blood.

If the thyroid decreases the production of hormones, the individual can experience other symptoms, such as constipation, cold intolerance, fatigue, and dry skin. The most common cause of hypothyroidism in the United States is Hashimoto thyroiditis. This chronic autoimmune condition causes an immune response, which causes damage and inflammation in the thyroid while producing autoantibodies. The thyroid produces low levels of thyroid hormone, while the pituitary makes more TSH, leading to a very high level in the blood.

The level of TSH does not always accurately reflect the level of thyroid hormone levels, however. Some individuals create an abnormal form of TSH, which doesn’t work correctly. These individuals have hypothyroidism even though their TSH Thyroid-Stimulating Hormone levels are normal or possibly even slightly elevated. With many thyroid diseases, the hormone levels can be too high or too low, regardless of the amount of TSH present in the blood.

In some situations, pituitary dysfunction can cause decreased or increased amounts of TSH. Hyperthyroidism or hypothyroidism can happen if there is an issue with the hypothalamus, leading to insufficient or excessive TRH.

Typically, a TSH test is ordered along with a free T4 test. A free T3 test may also be ordered. It could also include a test of the levels of thyroid antibodies if any type of autoimmune-related thyroid disease is suspected. In some cases, numerous labs related to the thyroid are all ordered together as a thyroid panel.

Testing TSH can help doctors:

  • Determine if a patient has a thyroid disorder 
  • Monitor anti-thyroid treatment in patients who have been diagnosed with hyperthyroidism
  • Diagnose and monitor ongoing infertility issues in female patients, so that they can be treated appropriately
  • Screen infants for an underactive thyroid so that treatment can begin as soon as possible
  • Determine how well the pituitary gland is functioning overall
  • Screen adults for thyroid disorders, although medical opinions vary as to when this screening should occur.
  • Monitor thyroid replacement therapy in individuals who have been prescribed the therapy and diagnosed with hypothyroidism

When is This Test Ordered?

Healthcare providers can order a TSH test if someone has an enlarged thyroid gland, or if they have the symptoms of hypothyroidism or hyperthyroidism.

Signs and symptoms of hyperthyroidism can include:

  • Increased heart rate with no other cause
  • Ongoing anxiety that is not psychologically caused
  • Unexplained weight loss
  • Insomnia with no other cause
  • Hand tremors with no neuromuscular cause
  • Weakness in the body
  • Occasional diarrhea
  • Visual disturbances
  • Sensitivity to Light

Ocular symptoms: Puffiness around the eyes, bulging eyes, dryness, and irritation.

Individuals who suffer from hypothyroidism can experience:

  • Unexplained weight gain, not as a result of medications or diet
  • Ongoing constipation
  • Dry, flaky skin
  • Cold intolerance
  • Puffy skin
  • Hair loss
  • Fatigue
  • Irregular menstrual periods

TSH can be ordered at regular intervals when a patient is being treated for an existing thyroid disorder. The American Thyroid Association recommends waiting six to eight weeks after having thyroid medication adjusted before testing the level of TSH.

TSH screening is typically performed routinely in the United States on newborns as part of individual state’s newborn screening programs. This helps ensure that thyroid deficiencies are caught and treated early so that these individuals can lead healthy lives.

The U.S. Preventative Services Taskforce found insufficient evidence in 2004 to recommend either for or against regular screening at a specific age for adults with no symptoms. However, both the American Association of Clinical Endocrinologists and the American Thyroid Association released guidelines in 2012, suggesting that doctors consider screening patients older than 60 for hypothyroidism. The signs and symptoms of both hyperthyroidism and hypothyroidism are very similar to those of numerous other disorders. This makes it important for healthcare providers to rule out these diseases even if a patient has other health issues.

What Does the Test Result Mean?

A high TSH result can mean that:

The patient being tested has an underactive thyroid gland. The gland may not be functioning or responding to the stimulation of TSH. They may have thyroid dysfunction, either chronic or acute. Testing allows medical professionals to keep up with TSH levels and medication levels to help keep their patients healthy.

If a patient with hypothyroidism has their thyroid removed, their medication doses could be incorrect and may need to be adjusted. The same can be true of individuals with hyperthyroidism. These issues make medication monitoring and testing vital for these individuals. There is an issue with the pituitary gland, like a tumor, leading to unregulated production of TSH.

A low TSH result can indicate:

  • An overactive thyroid gland
  • Too much thyroid hormone medication in individuals who have had their thyroid gland removed or have an underactive thyroid gland. This makes it important to monitor medication levels carefully.
  • Insufficient anti-thyroid medication in an individual who’s being treated for hyperthyroidism. It can take some time, however, for natural TSH production to resume after successful treatment. This is why the recommendation is that the treatment is monitored with tests for T4 and T3, as well as TSH levels.
  • Damage to the pituitary gland that keeps it from producing enough TSH
  • An abnormal TSH indicates that there is an issue with the amount of thyroid hormone available in the body, but it does not tell us why. An abnormal TSH test result typically requires additional testing to discover the cause of the increase or decrease.

What Else Should I Know? 

It’s important to know that TSH, free T4, and free T3 test results are only a snapshot of what is happening within a dynamic system, and do not provide a healthcare professional with all the necessary information. Each individual’s thyroid test results can vary and can be affected by:

  • Increases, decreases, and changes in the proteins that bind T3 and T4.
  • Pregnancy
  • Estrogen
  • Other Drugs
  • Liver Disease
  • System-Wide Illness
  • Resistance to Thyroid Hormones

Many medications can affect the results of thyroid gland function tests, and it’s important to discuss their use with your doctor before the test itself. They can then advise you if you should take the medication on the day of the blood draw.

Illnesses that are not directly related to your thyroid – nonthyroidal illnesses – can still change the levels of thyroid hormones. The level of T3 can be low in nonthyroidal illnesses. Usually, the thyroid hormone levels go back to normal once the person has healed from the illness. This condition used to be called “euthyroid sick syndrome,” but this term has become controversial, as there is debate as to whether the thyroid functions normally (euthyroid).

If your doctor adjusts your thyroid hormone replacement dosage, it’s crucial to wait for at least a month or two before having the TSH level checked again, so that the new dose can fully take effect.

Acute illness and extreme stress can also affect TSH test results. It’s usually recommended that thyroid testing should be avoided in patients who are hospitalized or put off until you are well if you’re suffering from an acute illness.

Results can also be low during the first trimester of pregnancy.

Do Health Care Providers Test TSH During Pregnancy?

Healthcare providers don’t usually test women with no symptoms, but if a patient has symptoms or a thyroid disorder, they may be tested at specific intervals to detect or evaluate the thyroid disorder throughout the pregnancy and after.

The thyroid is located at the base of the neck. It is a small, butterfly-shaped gland that produces thyroid hormones such as thyroxine or T4 and triiodothyronine or T3.  These hormones are required for the regulation of the metabolism as they tell your cells how fast to use energy and produce protein.  This gland is also responsible to produce calcitonin, which is the hormone that regulates calcium levels in the blood by preventing the breakdown of bone.  It also increases the elimination of calcium from the kidneys.  To control the amounts of T3 and T4, the body has an elaborate feedback system.  

When there is a decrease in the hormones in the blood, the hypothalamus will release thyrotropin-releasing hormones.  These tell the pituitary gland to start releasing the thyroid-stimulating hormone TSH.  The thyroid gland will then start to produce and release T4 and T3.   

As the thyroid hormone levels begin to increase, the pituitary gland will reduce the amount of TSH released.  This will tell the thyroid to start producing less T4 and T3.  In normal circumstances, this system will regulate the activity of the thyroid gland and ensure stable levels of necessary hormones in the blood.  

The thyroid can suffer from thyroid nodules, which are abnormal growths in the tissue of the gland that causes a lump or swelling.  These nodules can occur at any age but will be more common as people get older.  They are also more common in women.  According to the American Thyroid Association, approximately half of all people will have thyroid nodules that are visible on imaging by the age of 60.  However, these nodules will only be large enough to detect in a physical exam in around 5% of adults.  

Most thyroid nodules are found in people by chance because they do not cause any symptoms.  They are usually found when imaging scans are done for other conditions such as routine neck evaluations.  It is possible that you might notice a lump in your neck, and this should be brought to your doctor’s attention.  When found, the nodules and the gland will need to be evaluated, but more than 90% are considered benign.  However, a small percentage can be cancerous.  

Thyroid nodules can: 

  • Exist as a single nodule or be present as multiple nodules 
  • Be filled with fluid, be solid or a mixture of both 
  • Be large or small 
  • Grow slowly, but some can grow rapidly while others shrink 
  • Occasionally be large enough to compress the throat causing difficulty breathing and swallowing as well as pain 
  • Rarely affects the vocal cords to cause hoarseness, and those that do are more likely to be cancerous 
  • Produce T3 or T4, but most will not.  

Testing for Thyroid Nodules 

The Initial Testing 

To test for thyroid nodules, a combination of imaging tests and laboratory testing can be used.  These tests will also evaluate the nodules and thyroid gland.  

Blood Tests 

These tests will look for TSH but can look for T4free and T3free or Total T3.  The test helps to determine if the gland is functioning correctly.  These tests can also help to determine if the thyroid nodules are producing an excess of thyroid hormones.   

An Ultrasound 

One of the first tests generally ordered is an ultrasound of the thyroid gland.  This scan will help with the evaluation of the thyroid nodules.  The results of the test can help determine the location, shape, size, and other characteristics of the nodules.  The test can also determine if there is more than one nodule.  Ultrasounds can also: 

  • Evaluate the other structures in the neck such as the lymph nodes 
  • Determine if a fine needle aspiration biopsy will have to be done.  If so, the test can also help guide the placement of the needle during the biopsy. 
  • Monitor the thyroid gland and nodules over time 

Fine Need Aspiration Biopsy (FNA) 

As the name suggests, a healthcare professional will insert a thin needle into the thyroid gland.  They will then remove a small amount of fluid or tissue from the nodule.  The collected cells will be examined by a pathologist to determine if the nodules are cancerous or not.   

To report the results of the biopsy, a standardized system known as the Bethesda System will be used.  With each finding, the associated risk of cancer is assigned.  The results will generally be reported in the following manner: 

  • Unsatisfactory or non-diagnostic – this was when there were too few cells collected to make a proper diagnosis.  A risk of 5% to 10% of cancer is assigned.  A repeat FNA will generally need to be carried out.  
  • Benign – the cells show a risk of 0 to 3% for cancer.  
  • Atypia or follicular lesion of undetermined significance – the cancer risk is between 10% and 30%. 
  • Follicular lesion – this is cancerous 25% to 40% of the time. 
  • FLUS, AUS, and follicular lesion of indeterminate results – this is when there were enough cells present in the sample to be examined, but a reliable diagnosis could not be provided. 
  • Suspicious for malignancy – this will have a cancer risk of 50% to 75%. 

A second biopsy might be required depending on the initial results.  Surgery may also be required.  

Additional Tests 

Molecular Tests 

If the results of the biopsy are unclear or indeterminate, genetic testing of the cells can be performed.  This will help to detect any cancer-causing mutations in the genetic material of the cells.  Genetic testing panels are available to determine if the nodule is cancerous.  These tests will also help determine if surgery is required.   

Molecular tests have been recognized by the American Thyroid Association as useful supplemental information.  They are recommended but should be used with caution.  They should also not replace ultrasounds and other clinical findings or clinical judgment.  It is important to note that the absence of mutated genes associated with thyroid cancer does not exclude the possibility completely.  

Calcitonin Test 

This is a blood test that is not regularly used for evaluating these nodules.  However, it can be ordered to determine if the thyroid gland is producing excess calcitonin.  Elevated levels are used as an indicator of C-cell hyperplasia, but other procedures will be used to finalize the diagnosis.  

Thyroid Scans 


This scan is used to evaluate the thyroid gland.  Its ability to detect cancer is still being studied.  The scan will use a small volume of radioactively labeled glucose and follow up testing may be done depending on the results.  

Radioactive Iodine Scan 

This scan is not carried out regularly anymore because the FNA and ultrasound will be better at evaluating the thyroid nodules.  However, this can still be done in rare cases when a person has both thyroid nodules and hyperthyroidism.  A nodule that produces excess thyroid hormones will take up more radioactively labeled iodine than the normal thyroid tissue.  This will show up on the scan.