Thyroid function tests
Thyroid function tests are used to check whether your thyroid is working normally.
The most common thyroid function tests are:
- Free T4 (the main thyroid hormone in your blood -- a precursor for T3)
T4
T4 (thyroxine) is the main hormone produced by the thyroid gland. A laboratory test can be done to measure the amount of free T4 in your blood. Fre...
Read Article Now Book Mark Article - TSH (the hormone from the pituitary gland that stimulates the thyroid to produce T4)
TSH
A TSH test measures the amount of thyroid stimulating hormone (TSH) in your blood. TSH is produced by the pituitary gland. It prompts the thyroid g...
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Total T3 (the active form of the hormone -- T4 is converted to T3)
T3
Triiodothyronine (T3) is a thyroid hormone. It plays an important role in the body's control of metabolism (the many processes that control the rate...
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If you are being screened for thyroid disease, often only the thyroid stimulating hormone (TSH) test may be needed.
Other thyroid tests include:
- Total T4 (the free hormone and the hormone bound to carrier proteins)
- Free T3 (the free active hormone)
- T3 resin uptake (an older test that is rarely used now)
T3 resin uptake
The T3RU test measures the level of proteins that carry thyroid hormone in the blood. This can help your health care provider interpret the results ...
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Scan
A thyroid scan uses a radioactive iodine tracer to examine the structure and function of the thyroid gland. This test is often done together with a ...
Read Article Now Book Mark Article - Thyroid hormone binding globulin
- Thyroglobulin
- Anti-thyroid antibody tests
The vitamin biotin (B7) can affect the results of many thyroid hormone tests. If you take biotin, talk to your provider before you have any thyroid function tests.
Reviewed By
Robert Hurd, MD, Professor of Endocrinology and Health Care Ethics, Xavier University, Cincinnati, OH. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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Kim G, Nandi-Munshi D, Diblasi CC. Disorders of the thyroid gland. In: Gleason CA, Juul SE, eds. Avery's Diseases of the Newborn. 10th ed. Philadelphia, PA: Elsevier; 2018:chap 98.
Salvatore D, Cohen R, Kopp PA, Larsen PR. Thyroid pathophysiology and diagnostic evaluation. In: Melmed S, Auchus RJ, Golfine AB, Koenig RJ, Rosen CJ, eds. Williams Textbook of Endocrinology. 14th ed. Philadelphia, PA: Elsevier; 2020:chap 11.
Weiss RE, Refetoff S. Thyroid function testing. In: Jameson JL, De Groot LJ, de Kretser DM, et al, eds. Endocrinology: Adult and Pediatric. 7th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 78.