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What Is A Thyroid Blood Test Called

The Eight Blood Tests You Need To Assess Thyroid Function

Which Thyroid Blood Tests Should You Do?

December 6, 2017 by Megan

You didnt read that wrong. Thats right. I said the EIGHT blood tests for thyroid function assessment that you need to have run.

Now hold on, you think. My doctor only runs TWO blood tests for thyroid function TSH and T4. What am I missing??

Six other blood tests. Thats what youre missing.

Yes, TSH and T4 are important in the big picture of thyroid health, but without the other 6, MANY thyroid conditions often go undiagnosed. So you could be feeling like crap, wondering whats going on because your thyroid is normal according to your doctor.

Alright, lets get to it. Here are the EIGHT MOST IMPORTANT blood tests you need to have run in order to assess proper thyroid function.

Is Tsh Over 25 Indicative Of Disease


1 in 10 of people with TSH values above 3.0 mIU/L has Hashimotos .

TSH itself, as a marker of disease is not enough. If you have any symptoms connected to thyroid, talk to your health provider and get the full thyroid blood work done. This is the best first step towards understanding the health of your thyroid.

When Should I Take My Kid For The Thyroglobulin Test

If you observe thyroid dysfunction signs and symptoms in your kids, the thyroglobulin test is highly recommended. Some of the common symptoms noticed in kids having thyroid dysfunction are: Yellowing of the skin and whites of the eyes . In most cases, this occurs when a babys liver cant metabolize a substance called bilirubin, which normally forms when the body recycles old or damaged red blood cells.

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Thyroid Hormone Level Tests

There are four main thyroid hormones that have been identified: T1, T2, T3 and T4.

T4 and T3 are the two main thyroid hormones. T4 is known as prohormone and is 300 percent less biologically active than T3. T3 is the main biologically active thyroid hormone and gives us beautiful hair, replenishes our energy, and runs our metabolism.

You may have put together that most of the commonly prescribed thyroid medications like Synthroid and levothyroxine, only contain T4 , and thus they need to be converted to the active T3 form in the body.

On paper, the T4 to T3 conversion happens just fine, but in the real world, in real human bodies, we may not always convert T4 to T3.

We can reveal our T4 to T3 ratios and measure the hormone that is available to do its job in the body, by testing our free T4 and free T3 levels.

Free T3 and Free T4 tests measure the levels of active thyroid hormone circulating in the body.

Some clinicians may only test for T4, but T3 is also important to test, as some individuals may not be converting T4 to the active T3 properly. Thus, people may have a normal T4, but a low T3 level.

How Do You Know If You Are Converting Correctly?

Take a look at your free T3 and free T4 levels. Both should be in the optimal range. If the T4 is optimal, but the T3 is out of the optimal range, you know that your body is not making enough T3 hormone from the T4.

Optimal T4 reference range: 15-23 pmol/L

Optimal T3 reference range: 5-7 pmol/L

What Does It Mean To Have A Blood Value Out Of Range

Various Thyroid Tests: Procedures Involved and Results

Medically accepted averages vary from country to country.

If youve moved around a lot, it can be challenging to determine which countrys averages are applicable to you do the averages from your country of origin apply to you or has your averages changed to fit your new environments averages? Keep this in your mind if you are relocating.

One measurement at one point in time will not tell you much. You should re-test one or two times for accuracy. This way you and your healthcare practitioner can actually get a solid overview of your health.

TSH test is a first step towards the diagnosis of hypothyroidism. However it can be very misleading, as its shown to increase with age and its not an immediate sign of a disease .

The same is true for kids. From birth to late childhood they have high TSH values, which eventually drops as they reach puberty .

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What Is A T3 Test

T3 TestsT3 tests measure triiodothyronine levels in the blood. A Total T3 test measures the bound and free fractions of triiodothyronine. Hyperthyroid patients typically have an elevated Total T3 level. T3 tests can be used to support a diagnosis of hyperthyroidism and can determine the severity hyperthyroidism.

In some thyroid diseases, the proportions of T3 and T4 in the blood change and can provide diagnostic information. A pattern of increased T3 vs T4 is characteristic of Graves disease. On the other hand, medications like steroids and amiodarone, and severe illness can decrease the amount of thyroid hormone the body converts from T4 to T3 resulting in a lower proportion of T3.

T3 levels fall late in the course of hypothyroidism and therefore are not routinely used to evaluate patients with underactive or surgically absent thyroid glands.

Measurement of Free T3 is possible, but is often not reliable and therefore may not be helpful.

Thyroid Blood Test Normal Range

Total thyroxine

  • 0-5 days of age: 5.0-18.5 mcg/dL
  • 6 days-2 months: 5.4-17.0 mcg/dL
  • 3-11 months: 5.7-16.0 mcg/dL
  • 11-19 years: 5.9-13.2 mcg/dL

Adult : 4.5-11.7 mcg/dL

  • Values of more than 11.7 mcg/dL in adults or more than the age-related cutoffs in children are seen in hyperthyroidism and patients with acute thyroiditis.
  • Values below 4.5 mcg/dL in adults or below the age-related cutoffs in children are seen in hypothyroidism, myxedema, cretinism, chronic thyroiditis, and occasionally, subacute thyroiditis.
  • Increased total thyroxine is seen in pregnancy and patients who are on estrogen medication. These patients have increased total T4 levels .
  • A thyrotropin-releasing hormone stimulation test may be required for certain cases of hyperthyroidism.

Clinical findings are necessary to determine if thyroid-stimulating hormone, TBG, or free T4 testing is needed.

Free thyroxine

Adult : 80-200 ng/dL

Free triiodothyronine

  • Age > or =1 year: 2.8-4.4 pg/mL

Normally triiodothyronine circulates tightly bound to thyroxine-binding globulin and albumin. Only 0.3% of the total T3 is unbound the free fraction is the active form.

Thyroid stimulating hormone

Thyroid stimulating hormone normal levels:


  • 11-19 years: 0.5-4.3 mIU/L

Adults : 0.3-4.2 mIU/L

For diagnostic purposes, the results should always be assessed in conjunction with the patients medical history, clinical examination and other findings.

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Who Orders My Blood Tests

Your doctor typically orders blood tests for you during a physical, checkup, or an appointment intended for a specific condition.

Blood testing is usually partially or fully covered by insurance. Ordering tests through your medical provider ensures that youre not paying too much. Your doctor can also advise you on how to choose testing facilities that are reliable, well-managed, or convenient for you.

Its possible to order your own blood tests without a doctor or even health insurance, but its not recommended. You may end up paying the full cost by not going through an insurance plan, which can be expensive.

And some blood testing facilities may not give you accurate results. One infamous case of this is Theranos, a Palo Alto, California, biotechnology firm shut down in 2018 when an investigation uncovered lies and fraud around the accuracy of its private blood testing technology.

Normal levels can also vary by age.

What Should I Do To Prepare For A Thyroid Function Test

Thyroid Function Test – Get an overview

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.

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What Initial Screening Tests Are Used To Evaluate Hyperthyroidism In Cats

Thyroid hormones have widespread effects on the body, and are involved in the metabolism of food as well as the daily metabolic functions of most of the body’s tissues and organs. Therefore, the effects of increased thyroid hormone concentrations may be seen in many initial blood and serum screening tests. Changes in the initial screening tests may suggest the presence of hyperthyroidism, and may uncover other conditions, some of which may be related to increased thyroid hormone production while others may indicate other, non-related problems.

Complete blood count . The white blood cells, red blood cells, and platelets are evaluated in this test. Hyperthyroidism does not usually cause significant changes in the blood cell profile, with the exception of a mild increase in red blood cell numbers. Therefore, the presence of significant alterations in any of these blood parameters may alert your veterinarian to the existence of other disease conditions.

Serum biochemistry profile. Serum contains enzymes, proteins, lipids , glucose , and metabolites. The use of a serum biochemistry profile allows your veterinarian to measure these components of serum and provides specific values for enzymes related to the liver, kidneys and pancreas, in addition to an evaluation of the electrolyte components of a serum sample, such as sodium and potassium.

What Is Thyroid Function Test

Thyroid function test is used to check how well your thyroid is working and to find the cause of problems such as hyperthyroidism or hypothyroidism. The thyroid is a small, butterfly-shaped gland in the front of your neck that makes two thyroid hormones: thyroxine and triiodothyronine . Thyroid hormones control how your body uses energy, so they affect nearly every organ in your body, even your heart.

Thyroxine and triiodothyronine circulate almost entirely bound to specific transport proteins, and there are some situations which these proteins could change their level in the blood, producing also changes in the thyroxine and triiodothyronine levels .

The thyroid function test usually includes:

The total T4 and total T3 tests have been used for many years, but they can be affected by the amount of protein available in the blood to bind to the hormone. The free T4 and free T3 tests are not affected by protein levels and are thought by many to be more accurate reflections of thyroid hormone function. In most cases, the free T4 test has replaced that of the total T4 test. However, some professional guidelines recommend the total T3 test, so either total T3 or free T3 test may be used to assess thyroid function.

Thyroid blood tests help health care professionals diagnose thyroid diseases such as:

Your doctor will start with blood tests and may also order imaging tests.

  • Increases, decreases, and changes in the proteins that bind T4 and T3
  • Pregnancy

What is reverse T3?

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Are Normal Values The Same For Everyone

No. Whats normal for you might not be normal for the person next to you.

Whats normal for you today will likely not be normal for you in the future.

Your weight, stress levels, or dietary habits might change you might get pregnant, move countries, and more. These variables and your genes will determine your normal values for any given moment in your life.

Why Your Doctor Is Wrong About Thyroid Testing

Thyroid Blood Testing

Youre having symptoms of low thyroid function fatigue, weight gain, hair loss, brain fog and more but your doctor insists that your thyroid test results are within normal range, so your thyroid is fine.

How can that be?

An estimated one in five women aged 60 and older has some form of thyroid dysfunction, yet a huge number of these women will go undiagnosed by their doctors. In this short video, Dr. Mary James explains why the standard thyroid test, TSH, often fails to accurately diagnose hypothyroidism and she tells you about the two tests that can help reveal low thyroid function, so you can finally restore your thyroid health and start feeling the way you want to feel.

Scroll down for the transcription.

How TSH results can hide hypothyroidism

Hey everyone! Dr. Mary James here, with Women’s Health Network.

Low thyroid function is so common among women that you’ve probably been tested for it when you’ve had symptoms like fatigue, weight gain, or hair loss. Maybe youve even been tested more than once and probably any time youve been tested, its been with a TSH test.

Did your doctor ever tell you that your thyroid was normal based on TSH test results, but you continued to feel lousy?

Well Im going to tell you why, in too many cases, the TSH test is unreliable in which case you could indeed be hypothyroid, but its going undetected.

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What Are The Different Types Of Thyroid Blood Tests

The three types of thyroid blood tests are the total thyroxine test, the free thyroxine test and the triiodothyronine test. Each of these tests can determine whether the thyroid is releasing the appropriate number of hormones in the body. The blood tests also can be used to monitor whether a thyroid treatment plan is working and can be a first step in determining whether thyroid diseases or disorders are present.

The thyroid gland is located in front of the trachea, or windpipe, and below the voice box. Iodine from food is used to make hormones called thyroxine and triiodothyronine, also known as T4 and T3, respectively. The thyroid stores and releases these hormones as the body needs them.

Thyroid blood tests in adults are important because the thyroid gland produces the hormones that regulate the bodys metabolism. In babies, the thyroid helps in brain development. It often is recommended that thyroid functioning is tested in babies, because deficiencies can lead to mental retardation. In older children, the thyroid helps regulate normal growth.

What Does A Full Thyroid Panel Include

Thyroid stimulating hormone

âThe pituitary gland produces thyroid-stimulating hormone in the brain. The primary job of TSH is to regulate the amount of thyroid hormonesâthyroxine and triiodothyronine âproduced by the thyroid gland. This blood test measures how much overall thyroid-stimulating hormone is in your blood. While this is the standard test most doctors authorize, it wont provide detailed information on your thyroid activity. For instance, it may not show problems like your body not being able to use the available thyroid hormone.

Free T4

The thyroid produces two hormones: thyroxine and triiodothyronine . T4 is primarily inactive. Its primary job as a storage hormone is to transport T3 to the proper organs in your body. T4 must be converted to T3 before your body can use it to get energy or deliver oxygen to cells. The T4 test helps determine the level of thyroid hormone in the body however, it doesnt provide enough information by itself because it can be affected by the amount of protein in your blood.

Free T3

Reverse T3

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Why You May Need A Thyroid Test

Women of all ages are more likely than men to have low thyroid hormone levels. However, many of their symptoms are attributed to other conditions or written off as a consequence of aging.

A blood test for levels of TSH is the most sensitive test for determining whether you have hypothyroidism. Most laboratories use 0.45 5.00 mIU/L as a normal reference range for TSH. People with TSH between 5.00 and 9.99 mIU/L often have no symptoms , but some do. Another test called T4 will be done if your TSH is in this range. A low level of T4 usually means you will benefit from thyroid hormone replacement.

Many people with hypothyroidism or subclinical hypothyroidism aren’t aware anything is wrong because they haven’t been tested. The U.S. Preventive Services Task Force doesn’t recommend thyroid screening because it hasn’t found sufficient evidence that testing thyroid hormone levels in large groups of people without symptoms is cost-effective. Dr. Garber agrees, and suggests a different approachtesting asymptomatic people who are most likely to develop thyroid disease and benefit from treatment.

Treating subclinical hypothyroidism with synthetic thyroid hormone may reduce the risk of developing more serious problems like cardiovascular disease. They note that low thyroid hormone can cause a high cholesterol level and treatment with thyroid hormone may make statin therapy unnecessary.

Why It Is Done

Thyroid Blood Tests | Thyroid Series | Dr.Ravi Sankar | Endocrinologist | Hi9

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.

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What Is The Bone Profile Blood Test

The bone profile test measures and analyses the enzymes, proteins, and minerals that are present in your bones. It is a crucial test for monitoring the health of your bones and for ensuring that they are developing and repairing themselves properly.

What is the bone profile used for? Well, as we said, healthy bones are crucial for movement, posture, and overall wellbeing and, as you age, they naturally weaken. As a result, the older men among us should consider taking the test.

Alongside overall health, the bone profile is used in the analysis and monitoring of some particular conditions. These include:


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