TH-3. Thyroid Health

The following is a list of what is included in the item above. Click the test(s) below to view what biomarkers are measured along with an explanation of what the biomarker is measuring.

Also known as: Reverse T3, Reverse Triiodothyronine, RT3, T3 Reverse RT3 LCMSMS, Triiodothyronine Reverse

T3 Reverse, LC/MS/MS

Reverse T3 produced in the thyroid comes from the conversion of the storage hormone T4. Your body, especially the liver, can constantly be converting T4 to RT3 as a way to get rid of any unneeded T4. In any given day approx. 40% of T4 goes to T3 and 20% of T4 goes to Reverse T3. However in any situation where your body needs to conserve energy and focus on something else, it will change the above percentages, changing the conversion of RT3 to 50% or more, and the T3 goes down, down. Examples are emotional, physical, or biological stress, such as being chronically or acutely sick (the flu, pneumonia, etc), after surgery, after a car accident or any acute injury, chronic stress causing high cortisol, being exposed to an extremely cold environment, diabetes, aging, or even being on drugs like beta blockers and amiodarone.

Also known as: Triiodothyronine

T3, Total

Triiodothyronine (T3) is a thyroid hormone. It plays an important role in the body's control of metabolism.

Also known as: Free T3, FT3, T3 Free

T3, Free

This test measures the amount of triiodothyronine, or T3, in the blood.

Also known as: T4 Thyroxine Total

Free T4 Index (T7)

FTI stands for the Free Thyroxine Index and is also sometimes referred to as T7. It is a calculated value determined from the T3 uptake test and total T4 test and provides an estimate of the level of free T4 in the blood.

T4 (Thyroxine), Total

This test measures the amount of thyroxine, or T4, in the blood. T4 is one of two major hormones produced by the thyroid gland. The total T4 test is used to help diagnose hyperthyroidism and hypothyroidism. It is a useful test but can be affected by the amount of protein available in the blood to bind to the hormone.

Also known as: Free T4, FT4, T4 Free

T4, Free

The free T4 test is not affected by protein levels. Since free T4 is the active form of thyroxine, the free T4 test is may be a more accurate reflection of thyroid hormone function.

Thyroglobulin Antibodies

Measurement of thyroglobulin antibodies is useful in the diagnosis and management of a variety of thyroid disorders including Hashimoto's thyroiditis, Graves Disease and certain types of goiter.

Thyroid Peroxidase

Also known as: Thyroid Stimulating Hormone, Thyroid Stimulating Hormone (TSH), Thyrotropin


A TSH test is a lab test that measures the amount of thyroid stimulating hormone (TSH) in your blood. TSH is produced by the pituitary gland. It tells the thyroid gland to make and release thyroid hormones into the blood.


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The TH-3. Thyroid Health panel contains 7 tests with 10 biomarkers.

Brief Description: The TH-3 Thyroid Health panel is a comprehensive set of tests designed to provide an in-depth evaluation of thyroid function and autoimmunity. This panel assesses the levels of thyroid hormones, including the active and inactive forms, and checks for antibodies that indicate an autoimmune thyroid disorder.

Collection Method: Blood Draw

Specimen Type: Serum

Test Preparation: Specifc to TSH: Specimen collection after fluorescein dye angiography should be delayed for at least 3 days. For patients on hemodialysis, specimen collection should be delayed for 2 weeks.

According to the assay manufacturer Siemens: "Samples containing fluorescein can produce falsely depressed values when tested with the Advia Centaur TSH3 Ultra assay."

When and Why the TH-3 Thyroid Health Panel May Be Ordered

Healthcare providers may order the TH-3 Thyroid Health panel for individuals exhibiting symptoms of thyroid dysfunction, such as unexplained weight changes, mood disturbances, temperature sensitivity, and energy level fluctuations. It is particularly useful for diagnosing autoimmune thyroid diseases like Hashimoto's thyroiditis or Graves' disease and for monitoring the progression and treatment of thyroid disorders.

What the TH-3 Thyroid Health Panel Checks For

  • T3 Reverse: Measures the inactive form of T3, providing insights into thyroid hormone metabolism and potential issues with thyroid hormone conversion.
  • T3 Total: Assesses the total amount of triiodothyronine in the blood, reflecting overall thyroid hormone production.
  • T3 Free: Measures the unbound and biologically active form of T3, offering insights into the functional thyroid hormone available to body tissues.
  • T4 Total: Evaluates the total amount of thyroxine, including both bound and free T4, to assess the thyroid gland's output.
  • T4 Free: Measures the unbound portion of thyroxine, providing a direct indicator of the hormone available for physiological actions.
  • Thyroid Peroxidase Antibodies (TPOAb): Checks for antibodies against thyroid peroxidase, an enzyme involved in thyroid hormone production, indicative of autoimmune thyroid disease.
  • Thyroglobulin Antibodies (TgAb): Measures antibodies against thyroglobulin, a protein involved in thyroid hormone storage, also suggesting autoimmune involvement.
  • Thyroid Stimulating Hormone (TSH): A central regulator of thyroid function, with its levels reflecting the pituitary gland's response to circulating thyroid hormone levels.

Getting a Deeper Understanding of Your Thyroid Health

For an even more comprehensive assessment, the TH-4 Thyroid Health panel expands on the TH-3 panel by including tests for TSH Receptor Binding Antibody and Thyroid Stimulating Immunoglobulin (TSI). These additional markers are particularly useful in diagnosing and managing Graves' disease, providing a detailed picture of thyroid autoimmunity and function, making it superior for complex thyroid conditions.

Conditions or Diseases the TH-3 Thyroid Health Panel Can Check For

The TH-3 Thyroid Health panel is instrumental in diagnosing and managing autoimmune thyroid diseases such as Hashimoto's thyroiditis and Graves' disease. It also helps in evaluating more subtle forms of thyroid dysfunction and monitoring the effectiveness of treatments for thyroid disorders.

Use of TH-3 Thyroid Health Panel Results by Healthcare Professionals

Healthcare professionals analyze the TH-3 Thyroid Health panel results to diagnose thyroid disorders, determine the autoimmune status, guide treatment decisions, and monitor the progression of thyroid diseases. The detailed thyroid hormone profile, along with autoimmune markers, provides crucial information for these purposes.

The TH-3 Thyroid Health panel offers a thorough evaluation of thyroid function and autoimmunity, providing essential insights for diagnosing and managing thyroid disorders. By combining detailed assessments of thyroid hormones with autoimmune markers, this panel enables healthcare providers to identify underlying thyroid conditions, tailor treatment strategies effectively, and monitor patient outcomes, ensuring comprehensive thyroid health management.

We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.

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