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What Is Meant By Thyroid Test

What Are Normal Thyroid Hormone Levels

Thyroid 101: What do your Thyroid tests results really mean?

The thyroid itself is regulated by another gland that is located in the brain, called the pituitary. In turn, the pituitary is regulated in part by the thyroid and by another gland called the hypothalamus.

The hypothalamus releases a hormone called thyrotropin releasing hormone , which sends a signal to the pituitary to release thyroid stimulating hormone . In turn, TSH sends a signal to the thyroid to release thyroid hormones. If a disruption occurs at any of these levels, a defect in thyroid hormone production may result in a deficiency of thyroid hormone .

Hypothalamus – TRH

Thyroid – T4 and T3

The rate of thyroid hormone production is controlled by the pituitary gland. If there is an insufficient amount of thyroid hormone circulating in the body to allow for normal functioning, the release of TSH is increased by the pituitary gland in an attempt to stimulate more thyroid hormone production. In contrast, when there is an excessive amount of circulating thyroid hormone, TSH levels fall as the pituitary attempts to decrease the production of thyroid hormone.

  • In persons with hypothyroidism , there is a continuously decreased level of circulating thyroid hormones.
  • In persons with hyperthyroidism , there is a continuously elevated level of circulating thyroid hormones.

Why Has The Doctor Asked Me To Under A Thyroid Profile Test

Individuals with abnormal thyroid levels tend to show these symptoms Unexplained weight changes either weight gain or weight loss Appetite changes Changes in levels of energy Anxiety and fast heartbeat Puffy face Sleep problems such as insomnia In addition to these, there are certain cases where thyroid hormone imbalance is seen as a result of autoimmune conditions such as Hashimotos disease. Here, the bodys immune system starts destroying healthy thyroid gland cells resulting in abnormal thyroid levels. If your doctor suspects any of these conditions as seen through the symptoms, he/she will ask you to undergo a thyroid profile test.

How Is Thyroid Disease Diagnosed

Sometimes, thyroid disease can be difficult to diagnose because the symptoms are easily confused with those of other conditions. You may experience similar symptoms when you are pregnant or aging and you would when developing a thyroid disease. Fortunately, there are tests that can help determine if your symptoms are being caused by a thyroid issue. These tests include:

  • Blood tests.
  • Physical exams.

Blood tests

One of the most definitive ways to diagnose a thyroid problem is through blood tests. Thyroid blood tests are used to tell if your thyroid gland is functioning properly by measuring the amount of thyroid hormones in your blood. These tests are done by taking blood from a vein in your arm. Thyroid blood tests are used to see if you have:

  • Hyperthyroidism.
  • Hypothyroidism.

The specific blood tests that will be done to test your thyroid can include:

These tests alone arent meant to diagnose any illness but may prompt your healthcare provider to do additional testing to evaluate for a possible thyroid disorder.

Additional blood tests might include:

Talk to your healthcare provider about the ranges for these thyroid blood tests. Your ranges might not be the same as someone elses. Thats often alright. If you have any concerns or worries about your blood test results, talk to your provider.

Imaging tests

An ultrasound typically takes about 20 to 30 minutes.

Physical exam

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Why It Is Done

Thyroid hormone tests are done to:

    • Find out what is causing an abnormal thyroid-stimulating hormone test. For more information, see the topic Thyroid-Stimulating Hormone . This is the most common reason for thyroid hormone tests.
    • Check how well treatment of thyroid disease is working. The free thyroxine value is often used to keep track of treatment for hyperthyroidism or hypothyroidism, if TSH is abnormal or if TSH is normal and a patient has pituitary disease.

What Does The Thyroid Gland Do

What Blood Test For Thyroid Gland Function and Cancer ...

The major thyroid hormone secreted by the thyroid gland is thyroxine, also called T4 because it contains four iodine atoms. To exert its effects, T4 is converted to triiodothyronine by the removal of an iodine atom. This occurs mainly in the liver and in certain tissues where T3 acts, such as in the brain. The amount of T4 produced by the thyroid gland is controlled by another hormone, which is made in the pituitary gland located at the base of the brain, called thyroid-stimulating hormone. The amount of TSH that the pituitary sends into the bloodstream depends on the amount of T4 that the pituitary sees. If the pituitary sees very little T4, then it produces more TSH to tell the thyroid gland to produce more T4. Once the T4 in the bloodstream goes above a certain level, the pituitarys production of TSH is shut off. In fact, the thyroid and pituitary act in many ways like a heater and a thermostat

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What Are Thyroid Hormones

The thyroid gland produces hormones that are essential for normal body metabolism. Blood testing is now commonly available to determine the adequacy of the levels of thyroid hormones. These blood tests can define whether the thyroid gland’s hormone production is normal, overactive, or underactive.

The thyroid gland is located in the lower part of the neck, below the Adam’s apple.The gland wraps around the windpipe and has a shape that is similar to a butterfly – formed by two wings and attached by a middle part .

The thyroid gland uses iodine to produce thyroid hormones.

  • The two most important thyroid hormones are thyroxine and triiodothyronine , which account for 99.9% and 0.1% of thyroid hormones present in the blood respectively.
  • However, the hormone with the most biological activity is T3.
  • Once released from the thyroid gland into the blood, a large amount of T4 is converted into T3 – the active hormone that affects the metabolism of cells.

My Thyroid Blood Test Is 16 What Does This Mean

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What Causes Thyroid Disease

The two main types of thyroid disease are hypothyroidism and hyperthyroidism. Both conditions can be caused by other diseases that impact the way the thyroid gland works.

Conditions that can cause hypothyroidism include:

  • Thyroiditis: This condition is an inflammation of the thyroid gland. Thyroiditis can lower the amount of hormones your thyroid produces.
  • Hashimotos thyroiditis: A painless disease, Hashimotos thyroiditis is an autoimmune condition where the bodys cells attack and damage the thyroid. This is an inherited condition.
  • Postpartum thyroiditis: This condition occurs in 5% to 9% of women after childbirth. Its usually a temporary condition.
  • Iodine deficiency: Iodine is used by the thyroid to produce hormones. An iodine deficiency is an issue that affects several million people around the world..
  • A non-functioning thyroid gland: Sometimes, the thyroid gland doesnt work correctly from birth. This affects about 1 in 4,000 newborns. If left untreated, the child could have both physical and mental issues in the future. All newborns are given a screening blood test in the hospital to check their thyroid function.

Conditions that can cause hyperthyroidism include:

What Does The Tsh Test Involve


The TSH blood test is often administered as part of a panel of blood tests in conjunction with an annual health exam. The test determines how well your thyroid is working by measuring the amount of thyroid-stimulating hormone in your blood. Its a non-fasting blood test, meaning you dont have to do anything special to prepare.

Physicians should take a TSH blood sample for thyroid patients every four to eight weeks after their initial diagnosis. TheATA recommends TSH testing every six to 12 months while youre on a stable medication dose and more often if your dose has changed.

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What Should I Do To Prepare For A Thyroid Function Test

Thyroid function tests usually require very little preparation.

You don’t need to fast before the blood test. And it doesn’t matter if you have taken your thyroid medicine just before the blood test.

Tell your doctor if you are taking any medication, as some medicines can alter the test results and how they are interpreted.

It is also important to mention if you have had any X-ray tests that have used a special contrast dye, as this may contain iodine which can affect the results. Levels of thyroid chemicals also change in pregnancy, so tell your doctor if you are pregnant when the test is taken.

Note: all newborn children have their thyroid function tested as part of the heel prick test which is offered to all babies and undertaken when they are 5 days old. See the separate leaflet called Newborn Baby Screening Tests for more information.

Low T3 Is It Relevant

Low T3 can be seen in a condition called non-thyroidal Illness .

It can occur during starvation and critical illness and is generally resolved when health is restored .

To a lesser degree, its suspected it can also occur during any chronic illness.

Currently there is not enough evidence that replacing T3 on its own is beneficial .

Summary: In certain conditions low T3 levels can be seen when TSH and T4 levels are normal. This is usually a result of illness or starvation.

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What Your Thyroxine Results Mean

Thyroxine is a thyroid hormone. Thyroxine is the inactive form of triiodothyronine. Thyroxine plays a role in a majority of the bodys cell functions such as digestion, muscle control, memory, the maintenance of strong healthy bones and brain development. Thyroxine levels can tell you a lot about your thyroid health.

What does high thyroxine mean?High thyroxine may indicate that you have an overactive thyroid . High thyroxine may also be caused by Graves disease , hyperfunctioning nodules on your thyroid and thyroiditis .

What does low thyroxine mean?Low thyroxine may indicate that you have an underactive thyroid . Low thyroxine may also be caused by Hashimotos thyroiditis , anti-thyroid medications , thyroid surgery, radiation therapy , pregnancy, iodine deficiency and in rare cases, pituitary disorder or congenital disease .

What Are T4 And T3

What a High TSH Really Means for your Thyroid + What ...

The thyroid hormones Thyroxine and Triiodothyronine are produced and secreted by the thyroid gland.

Each molecule of T4 and T3 is made up of a protein and iodine . T4 contains 4 molecules of iodide and T3 contains 3 molecules of iodide hence the names T4 and T3.

This is what T4 looks like. Its bound to 4 iodine molecules, while T3 is bound to 3.

Interestingly, thyroid hormones are the only compounds in the body that contain iodine. This is why dietary intake of iodine is important for thyroid health.

T4 is produced by the thyroid gland in much greater amounts than T3, around 90% more. This is because when T4 reaches organs and body tissue, its converted into T3.

So T4 is basically a stepping stone required for T3.

T3 is the active form of thyroid hormone in that it influences many body processes, in particular the regulation of metabolism .

Summary: T4 and T3 are hormones produced by the thyroid gland and are essential for life. The thyroid produces mainly T4, which is then converted to T3 in tissue and organs. T3 is the active hormone.

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Who Is Affected By Thyroid Disease

Thyroid disease can affect anyone men, women, infants, teenagers and the elderly. It can be present at birth and it can develop as you age .

Thyroid disease is very common, with an estimated 20 million people in the Unites States having some type of thyroid disorder. A woman is about five to eight times more likely to be diagnosed with a thyroid condition than a man.

You may be at a higher risk of developing a thyroid disease if you:

  • Have a family history of thyroid disease.
  • Have a medical condition .
  • Take a medication thats high in iodine .
  • Are older than 60, especially in women.
  • Have had treatment for a past thyroid condition or cancer .

What Should Your Tsh Level Be

Most laboratories classify normal TSH levels as between 0.4 and 4.5 milliunits per liter , according to theAmerican Thyroid Association . A normal TSH level in most cases, usually indicates that you dont have a thyroid problem.

TheATA reports that nearly 20 million Americans have some form of thyroid disease. Yet more than 60% of those with a thyroid disorder are unaware of their medical condition.

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Causes Of High Tsh Level

Hypothyroidism: This is a medical condition where the body is not able to produce sufficient hormones to manage your metabolism adequately. The symptoms of Hypothyroidism include dry skin, thinning hair, increased sensitivity to cold, muscle aches, impaired memory, unexplained weight gain, puffy face, constipation, hoarseness, fatigue, increased cholesterol level, depression and irregular menstrual periods. Some of the causes for this condition to develop are surgery, radiation therapy, psychiatric medications and autoimmune diseases. Treatment for hypothyroidism consists of medications, which will artificially replace these hormones.

Thyroid Disorder: These include thyroid cancer, enlarged thyroid gland or abnormal production of hormone which can cause malfunction of the thyroid gland. Treatment is needed for some of these conditions otherwise patient may experience unpleasant side effects, such as slow metabolism which causes damage to the body.

Pituitary Tumors: Rarely, high TSH level may indicate improper functioning of the pituitary gland. Sometimes, this can be due to growth of a group of cells on top of the pituitary gland . Most of the time, these tumors are noncancerous, however, they do disturb the bodily functions which leads to other negative side effects. High TSH level or overproduction of TSH results in an overactive thyroid gland.

What Is Thyroid Medication

TSH test explained | Thyroid stimulating hormone test | Thyroid function test | Blood TSH test

Thyroid Hormone Treatment Levothyroxine is thestandard of care in thyroid hormone replacement therapy and treatment of hypothyroidism. Levothyroxine is equivalent to the T4 form of naturally occurring thyroid hormone and is available in generic and brand name forms.

How do I take levothyroxine? To optimize absorption of your thyroid medication, it should be taken with water at a regular time each day. Multiple medications and supplements decrease absorption of thyroid hormone and should be taken 3-4 hours apart, including calcium and iron supplements, proton pump inhibitors, soy, and multivitamins with minerals. Because of the way levothyroxine is metabolized by the body, your doctor may ask you to take an extra pill or skip a pill on some days of the week. This helps us to fine tune your medication dose for your body and should be guided by an endocrinologist.

For patients with celiac disease or gluten sensitivity, a gluten free formulation of levothyroxine is available.

Some individuals may have genetic variant that affects how the body converts T4 to T3 and these individuals may benefit from the addition of a small dose of triiodothyronine.

Liothyronine is replacement T3 thyroid hormone. This medication has a short half-life and is taken twice per day or in combination with levothyroxine. Liothyronine alone is not used for treatment of hypothyroidism long term.

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What Is Thyroid Stimulating Hormone

Thyroid-stimulating hormone is a hormone that stimulates the thyroid gland to produce thyroid hormones. The pituitary gland secretes more TSH when blood levels of T4 and T3 fall below normal, and reduces the TSH secretion when T4 and T3 levels rise. The hypothalamus region of the brain regulates pituitary gland activity.

Treating Hypothyroidism With Replacement T4 And T3

Hypothyroidism is usually treated with synthetic T4 called levothyroxine or synthroid.

Desiccated thyroid can also be used effectively, which is a mix of T4 and T3 made from animal thyroid glands. However, there is no evidence desiccated thyroid is more beneficial than levothyroxine .

Some doctors may also prescribe T3 alongside T4 medications when treating a stubborn case of hypothyroidism. This is uncommon but often useful.

Summary: Synthetic T4 is the usual treatment for hypothyroidism. Desiccated animal thyroid is an effective alternative.

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Recap + Final Thoughts

The presence of anti-TPO antibodies is never a normal sign.

The presence of these antibodies combined with hypothyroid symptoms may indicate autoimmune thyroiditis.

If you are experiencing hypothyroid like symptoms then you should have a complete thyroid lab panel checked which includes antithyroid antibodies.

Due to the various issues with diagnosing and managing thyroid abnormalities, it will be important for you to have a basic understanding of how to diagnose and manage your condition.

Because autoimmune thyroiditis indicates both an inflammatory and autoimmune condition, it is treated differently from hypothyroidism.

For best results, patients should focus on a combination of supplements, diet, stress reduction and hormone replacement to reduce this inflammatory state.

Doing this early may help to preserve thyroid function long term.

Now its your turn:

Are your TPO antibodies elevated?

Are experiencing any of the symptoms of hypothyroidism or hyperthyroidism?

Leave your comments below!

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Mild Hypothyroidism: Who Should Be Treated

What Your Thyroid Test Results Really Mean

What to do about mild hypothyroidism is a subject that has been studied and debated for years. Mild hypothyroidism is also called subclinical hypothyroidism. It doesnt meet the standard definition of overt hypothyroidism. You may have no symptoms, and your thyroid function blood tests show a mixed picture.

Your free T4 level is normal, meaning your body is getting enough thyroid hormone. It is your TSH level that is above the normal range, which indicates your thyroid gland has to work harder to pump out that thyroid hormone.

One worry about mild hypothyroidism is the potential link between untreated subclinical hypothyroidism and coronary artery disease. Results of research on whether subclinical thyroid disease causes heart problems have been conflicting. However, the condition has been associated with heart and blood vessel abnormalities, and some studies suggest that treating mild hypothyroidism can improve various markers of heart structure and function.

However, there are potential downsides to treating subclinical hypothyroidism. There is the risk of overtreatment, which might cause symptoms, such as feeling jittery and insomnia. Also, long-term overtreatment can lead to loss of bone density.

If your TSH level is higher than 10 mIU/L, you should start treatment, because you will develop symptoms of an underactive thyroid, even if you dont have them now.

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