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What Is The Most Accurate Test For Thyroid Function

When Normal Tsh Does Not Reflect Euthyroidism

The Thyroid Factory: Understanding Thyroid Function and Thyroid Function Tests

As mentioned earlier, while there may be some controversy about where the normal range for TSH should lie,, current clinical guidelines are clear that a TSH in the upper normal range does not reflect hypothyroidism., The potential unreliability of a normal TSH to accurately reflect true thyroid status is an ever-increasing question raised by patients who suffer from a myriad of non-specific complaints. As mentioned previously, many times these complaints are extremely prevalent: overweight , obesity , depression , hair loss , and fatigue . The quest for a reason and eventual relief of these burdensome symptoms is understandable and, as such, a normal TSH result may lead to patient dissatisfaction and mistrust of their physician, whom they see as relying more on a biochemical test than their symptoms. Indeed, much of the print and internet-based literature fosters this mistrust of standard biochemical testing and provider reliance on such tests. An understanding of the actual prevalence for a truly unreliable TSH is, therefore, extremely helpful for primary providers as they discuss a normal TSH value with a sometimes skeptical patient.

Hypothalamic and/or Pituitary Disease

Other conditions

What Is Being Tested

Thyroid function tests are used to check for a number of thyroid problems. The tests measure the amount of different hormones including thyroid stimulating hormone , thyroxine , and triiodothyronine . Other tests on the thyroid include various antibodies related to thyroid tissue.

TSH is produced by the pituitary gland in the brain. TSH is carried in the blood to the thyroid gland, which sits at the front of the neck. From there, TSH influences how much T4 and T3 are released into the blood.

TSH, T3 and T4 levels can all be tested in the blood. Your doctor will probably test TSH first, then T3 and T4 if TSH is abnormal. Tests can also be used to measure antibodies to diagnose autoimmune thyroid disease.

How To Test For The Five Thyroid Patterns

The standard thyroid panel is insufficient for detecting these five patterns of thyroid dysfunction. Additional tests are needed to determine which thyroid pattern is affecting your patient.

A comprehensive panel of thyroid markers: This panel should include TSH, T3, T4, free T3, and free T4.

DUTCH test for assessing HPA axis function: This test can help you determine whether chronic stress and high cortisol are causing pituitary dysfunction, under-conversion of T4 to T3, or thyroid hormone resistance.

Estrogen and testosterone: Measuring these hormones can help you determine whether elevated or decreased TBG, respectively, are the cause of your patients hypothyroidism.

Fasting blood sugar and hemoglobin A1c, to assess blood sugar imbalances and insulin resistance, which contribute to hypothyroidism caused by pituitary dysfunction.

Ferritin and serum selenium, to identify deficiencies of iron and selenium.

Assess gut health: Stool testing, hydrogen breath testing for SIBO, and a urine organic acids profile can be used to identify potential gut infections and dysbiosis contributing to hypothyroidism.

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Hypothyroidism Caused By Pituitary Dysfunction

This pattern is caused by high cortisol. Cortisol, in turn, is elevated in response to active infection blood sugar dysregulation, hypoglycemia, insulin resistance, or chronic stress or pregnancy. These stressors fatigue the pituitary gland as a result, it cant release enough thyroid-stimulating hormone to stimulate the thyroid gland to produce T4 and T3. In other words, there is nothing wrong with the thyroid gland itself the problem lies with the pituitary gland. The key to correcting this pattern is to resolve the underlying causes of pituitary dysfunction by treating infection, balancing blood sugar, improving insulin sensitivity, and helping patients find ways to reduce their stress levels.

Patients with this pattern will present with hypothyroid symptoms, TSH below the functional range but within the standard range , and T4 that is low in the functional range and possibly the standard range as well.

Thyroid Binding Globulin And T3 Uptake

Factors That May Affect Your Thyroid Test Results

TBG is a binding protein that binds free thyroid hormones T4 and T3. When TBG increases it reduces free hormone levels including free T3 levels, which may cause a functional hypothyroidism.

TBG levels can increase during pregnancy, high estrogen levels and liver disease. TBG levels can decrease during hyperthyroidism, Cushing Syndrome, malnutrition, renal disease and medications .

The way we measure TBG levels is through T3 uptake because it is easier to measure. The optimal T3 uptake level is 28-38%. The higher percentage the more binding sites are available. This happens with high estrogen which increases TBG and lowers T3 uptake levels. High estrogen can occur with birth control pills, sluggish liver, insulin resistance and estrogen dominance. This results in lower free T4 and T3 levels.

Elevated testosterone will reduce binding sites, which will increase T3 uptake and result in higher levels of free T3. In many cases, the TSH will be normal or low, the T4 levels will be normal or low but the free T3 levels will be high with elevated testosterone. High testosterone is associated with testosterone replacement and with insulin resistance in some women which can also lead to PCOS.

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Thyroid Disease In Pregnancy

Currently, there is insufficient evidence to advocate for universal screening . Based on the 2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum, if a woman is pregnant or planning pregnancy, TSH testing is indicated if she has any of the risk factors listed in Table 314. Pregnant women often experience symptoms that can be non-specific or vague and as such, it may be difficult to distinguish between symptoms of thyroid dysfunction and normal changes of pregnancy. Clinicians should have a low threshold for TSH testing in pregnancy.

Table 3. Risk Factors for Thyroid Disease in Women who are Pregnant or Anticipating Becoming Pregnant14

  • age > 30 years

Thyroid Function Test Results Explained

The thyroid usually changes slowly. It hardly ever quickly changes to being overactive or underactive: it usually takes a few weeks at least, or even a few months. If you have a thyroid function test that shows something is wrong, it’s usually worth repeating it in 3-6 weeks. That is because there’s always the chance that your thyroid gland could have gone back to normal by itself.

The second thing to bear in mind about thyroid function tests is that medications, and even herbal remedies or vitamin supplements, can affect the accuracy of thyroid results.

For these two reasons it’s always recommended to have a thyroid function test if it is recommended to you by a doctor, rather than having it done privately or without a doctor suggesting it.

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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.

Pattern #: Depressed Thyroid Binding Globulin Leading To Hypothyroidism

Thyroid-Stimulating Hormone | Correct TSH Test | Hypothyroidism

This is a pattern associated with High Testosterone. High Testosterone reduces thyroid binding hormone levels making more free hormones available.

The thyroid and pituitary are again working properly, but this time there is too much T4 converted to T3 . High levels of testosterone is the cause which also has the added effect of decreasing the amount of thyroid binding globulin .

The high levels of T3 in conjunction with low TBG causes cells to become resistant to T3. They close the doors and do not allow anymore T3 into the cells. TSH levels will be normal even though the patient is showing signs of hypothyroidism.

This pattern is similar to insulin resistance. In fact, patients with thyroid over conversion often also present with insulin resistance and polycystic ovary syndrome which is also caused by increased testosterone levels. Managing blood sugar is extremely important. Since there is already too much T3, prescription thyroid medication will not help in this pattern.

Lab Evaluation: Normal or Low TSH, Normal or Low T4 & T3 Levels, Normal or High Free T4 & High Free T3 Levels

Common Causes: Testosterone replacement or insulin resistance.

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How To Properly Test Thyroid Function

If you are not feeling your best it would be wise to test thyroid function. Hypothyroidism is one of the fastest growing health conditions we are seeing today. Lethargy, depression and weight gain are the most common symptoms .

It has been estimated that 27 million people in America struggle with some form of thyroid disease and up to 80 percent of hypothyroidism cases are autoimmune based . However, mainstream healthcare is not even testing for autoimmune indicators the majority of the time. This article will go through how to properly test thyroid function.

Thyroid Tests Are Recommended For Anyone Who:

  • suspects thyroid problem,
  • has symptoms of thyroid disease,
  • has a family member with thyroid condition,
  • is a teenage girl who have delayed onset of menstruation,
  • is pregnant, trying to get pregnant or has recently given birth,
  • is around menopause,
  • the elderly,
  • has associated health conditions such as PCOS, celiac disease, dermatitis herpetiformis, different types of anemia, depression, autoimmune disease, hepatitis C, type I and II diabetes among others.

Conventional medicine relies on the standard thyroid blood test for TSH alone or a combination of TSH and total T4 thyroid hormone for a diagnosis and treatment of hypothyroidism. Due to the wide range of the normal thyroid test results which also varies from lab to lab, many people remain undiagnosed, untreated or undertreated.

In addition, TSH and T4 tests are used for screening of hypothyroidism but they are not intended for diagnosing autoimmune Graves and Hashimotos disease, postpartum thyroiditis and thyroid cancer. It takes time for Hashimotos to develop and progress to subclinical hypothyroidism and then a full-blown hypothyroidism that can be clinically detectable using standard thyroid tests.

Currently, there are about 22 types of thyroid dysfunctions that can result in low thyroid function. Most of them could not be diagnosed by using TSH test alone. To get accurate evaluation of your thyroid function more advanced blood tests are required.

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Can You Check Your Thyroid Levels At Home

Yes you can indeed test your thyroid levels at home. Not many people realize that it is now entirely possible to test the functioning of your thyroid from the comfort of your own home via convenient testing kits that you can order online. If you couldnt test at home, this guide would be much shorter.

Thankfully there are quite a few testing options available now. Most of the at-home test kits involve using a small lancet to prick a finger and collect some droplets of blood. These blood droplets are your test sample, which you will return to the lab for analysis. Its quick and painless.

The purpose of this guide is to explain:

  • How to test for thyroid problems at home.
  • What your best testing options are, along with our recommendations.
  • Why a well-functioning thyroid is so important to your well-being.
  • The symptoms of thyroid disorders.

After reading the guide, youll have all the necessary information to decide on the best test for yourself.

Two testing companies LetsGetChecked and Everlywell offer very accurate and high-quality thyroid tests that you can use at home. Right now, in our opinion, LetsGetChecked has the superior at-home thyroid tests and so we recommend them above all the rest. However, if you want to order from home but head to a local lab for testing, then HealthLabs should be your choice. Heres a handy chart comparing these popular test choices based on price and what the tests measure.

How Does The Thyroid Gland Function

Pin on Thyroid Testing

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. When the heater is off and it becomes cold, the thermostat reads the temperature and turns on the heater. When the heat rises to an appropriate level, the thermostat senses this and turns off the heater. Thus, the thyroid and the pituitary, like a heater and thermostat, turn on and off. This is illustrated in the figure below.

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Can I Take The Test At Home

At-home thyroid test kits are commercially available without a prescription and measure the same hormones as the traditional thyroid panel.

For at-home testing, you prick your finger to get the necessary blood sample. That sample is then mailed to a laboratory that conducts the thyroid panel and makes the results available to you directly.

While at-home testing can measure thyroid levels, it is generally not a substitute for a test ordered by your doctor. If an at-home test detects abnormal thyroid levels, your doctor will likely recommend a new blood sample and thyroid panel to confirm the results. At-home tests for thyroid labs may not be as accurate as tests done in a laboratory.

What Is A Normal Thyroid Level

Tests often used to assess thyroid hormone status include TSH and FT4 tests. The normal value for a laboratory test is determined by measuring the hormone in a large population of healthy individuals and finding the normal reference range. Normal ranges for thyroid tests may vary slightly among different laboratories, and typical ranges for common tests are given below.

TSH normal values are 0.5 to 5.0 mIU/L. Pregnancy, a history of thyroid cancer, history of pituitary gland disease, and older age are some situations when TSH is optimally maintained in different range as guided by an endocrinologist.

FT4 normal values are 0.7 to 1.9ng/dL. Individuals taking medications that modify thyroid hormone metabolism and those with a history of thyroid cancer or pituitary disease may be optimally managed with a different normal FT4 range.

Total T4 and Total T3 levels measure bound and free thyroid hormone in the blood. These levels are influenced by many factors that affect protein levels in the body, including medications, sex hormones, and liver disease. A normal Total T4 level in adults ranges from 5.0 to 12.0g/dL. A normal Total T3 level in adults ranges from 80-220 ng/dL.

Free T3 assays are often unreliable and not routinely used to assess thyroid function.

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What Do The Results From My Thyroid Function Test Mean

Your doctor will discuss the results of your thyroid function test with you.An abnormal TSH usually indicates a deficiency or an excess of thyroid hormones available to your body, but it does not indicate why this is happening. An abnormal TSH result is usually followed by additional testing of FT3 and/or FT4 to investigate the cause.A high TSH result:

  • often means an underactive thyroid gland
  • can also occur if you have an underactive thyroid gland and are receiving too little thyroid hormone medication
  • can indicate in rare cases a problem with your pituitary gland, such as a tumour.

A low TSH result:

  • can indicate an overactive thyroid gland or damage to your pituitary gland that prevents it from producing TSH
  • can also occur if you have an underactive thyroid gland and are receiving too much thyroid hormone medication.

The Nah Does Not Currently Consider Tsh And T4 Testing To Be Reliable Markers Of Thyroid Tissue Levels As Previously Believed

Thyroid Function & Testing

While the NAH concedes that there is no perfect thyroid test, testing free triiodothyronine, reverse triiodothyronine, and triiodothyronine/reverse-triiodothyronine ratios may provide more accuracy when checking for low tissue levels of active thyroid hormone.

Unfortunately, many of todays younger generation will not have the excellent test results that their forbearers had because theyre not enjoying the same level of health as their grandparents did two generations ago.

Because of todays American diet, our young people will likely never experience outstanding thyroid health unless theyre encouraged to change their eating habits to include principles and foods like those of the Body Ecology Way of Living.

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