The Top 10 Thyroid Lab Tests

The The Top 10 Thyroid Lab Tests panel contains 9 tests with 12 biomarkers.

The Top 10 Thyroid Lab Tests to Ask for and How to Interpret Them includes important tests for evaluating thyroid function and diagnosing thyroid-related disorders. Here's a brief description of each test:

  1. T3 Total: This test measures the total amount of triiodothyronine (T3) hormone in the blood, including both the bound and free forms. T3 is an active thyroid hormone that regulates metabolism.

  2. T3, Free: This test specifically measures the unbound or "free" form of T3 hormone in the blood, which is available to cells and tissues. It is a more accurate assessment of thyroid function compared to T3 Total.

  3. T4 (Thyroxine), Total: This test measures the total amount of thyroxine (T4) hormone in the blood, including both the bound and free forms. T4 is another thyroid hormone that is converted to T3 in the body.

  4. T4, Free: This test specifically measures the unbound or "free" form of T4 hormone in the blood. Like free T3, it is a more accurate assessment of thyroid function compared to total T4.

  5. T3 Reverse (RT3): This test measures the level of reverse T3, an inactive form of T3, which is produced when the body is under stress. Elevated levels of RT3 can indicate that the body is not properly converting T4 to active T3.

  6. Thyroid Peroxidase (TPO) Antibodies: This test detects the presence of antibodies against thyroid peroxidase, an enzyme involved in thyroid hormone production. High levels of TPO antibodies can indicate autoimmune thyroid conditions, such as Hashimoto's thyroiditis.

  7. Thyroglobulin Antibodies: This test measures the presence of antibodies against thyroglobulin, a protein involved in thyroid hormone synthesis. High levels can indicate autoimmune thyroid conditions, such as Hashimoto's thyroiditis and Graves' disease.

  8. TRAB (TSH Receptor Antibodies): This test detects the presence of antibodies that bind to and stimulate or block the TSH receptor. It is useful in diagnosing Graves' disease, an autoimmune condition that causes hyperthyroidism.

  9. TSH (Thyroid-Stimulating Hormone): This test measures the level of TSH in the blood, which is produced by the pituitary gland to stimulate the thyroid to produce T3 and T4. TSH levels help evaluate overall thyroid function and can indicate hypo- or hyperthyroidism.

  10. TSI (Thyroid Stimulating Immunoglobulin): This test detects the presence of TSI, which is an antibody that stimulates the thyroid to produce more thyroid hormone. High levels of TSI are associated with Graves' disease.

These tests provide a comprehensive evaluation of thyroid function and can help healthcare providers diagnose and manage various thyroid disorders.

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

TRAB

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

TSH

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.

TSH

Also known as: Thyroid Receptor Antibody, Thyroid Stimulating Immunoglobulin, TSI Thyroid Stimulating Immunoglobulin

TSI

*Process times are an estimate and are not guaranteed. The lab may need additional time due to weather, holidays, confirmation/repeat testing, or equipment maintenance.

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