Thyroid function tests
Thyroid function tests are used to tell whether your thyroid is working normally.
The most common thyroid function tests are:
- Total, or free T4 (the main thyroid hormone in your blood)
- TSH (the hormone from the pituitary gland that stimulates the thyroid to produce T4)
- T3 (the active form of the hormone -- T4 is converted to T3)
Other thyroid tests include:
- T3 resin uptake (an older test that is rarely used now)
- Thyroid uptake and scan
- Thyroid binding globulin
Salvatore D, Davies TF, Schlumberger MJ, Hay ID, Larsen PR. Thyroid physiology and diagnostic evaluation of patients with thyroid disorders. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 13th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 11.
Weiss RE, Refetoff S. Thyroid function testing. In: Jameson JL, De Groot LJ, eds. Endocrinology: Adult and Pediatric. 7th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 78.
Review Date: 2/3/2016
Reviewed By: Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.