Thyroid Function Tests

Definition

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
  • Thyroglobulin

References

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

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