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October 9, 1967

Common Tests of Thyroid Function in Serum

Author Affiliations

From the Department of Medicine, Harvard Medical School, and the Peter Bent Brigham Hospital, Boston. Dr. Refetoff is the recipient of a Damon Runyon Cancer Research Fellowship.

JAMA. 1967;202(2):135-136. doi:10.1001/jama.1967.03130150103020

Correct diagnosis of most common disorders of thyroid function can usually be achieved by a thorough clinical evaluation and confirmed by a few carefully selected laboratory procedures. There are now available a number of relatively specific and accurate tests for measurement of thyroid hormone synthesis, secretion, transport, and metabolic action. Unfortunately, none alone is fully diagnostic of any single thyroid disorder and all can be misleading as a result of a wide variety of factors which influence their pathophysiologic significance. This presentation will be limited to a brief discussion of a few serum measurements of thyroid function of clinical importance to medical practice. The reader interested in more detailed considerations of this extensive subject is referred to recent reviews.1,2

The two principal thyroid hormones, thyroxine (T4) and triiodothyronine (T3) are normally secreted into the circulation under the control of pituitary thyrotropin (TSH). They are transported through the