Thyroidal and peripheral production of thyroid hormones. Review of recent findings and their clinical implications

Annals of internal medicine, 87(6), 760-768

DOI 10.7326/0003-4819-87-6-760 PMID 412452 Source

Abstract

There are two biologically active thyroid hormones, thyroxine (T4) and triiodothyronine (T3). Most T3 is produced extrathyroidally, so that alterations in circulating thyroid hormone concentrations may occur as a result of both thyroidal and extrathyroidal abnormalities. Extrathyroidal T4 conversion to T3 is decreased in patients with different acute and chronic illnesses. When T4 conversion to T3 is impaired and serum T3 concentrations decline, serum concentrations of biologically inactive 3,3',5'-triiodothyronine (reverse T3) increase. In this review, we present current information on thyroidal and extrathyroidal T4 and T3 production in normal subjects and patients with various thyroid diseases and other illnesses, consider the physiologic significance of these changes, and discuss the value and interpretation of various iodothyronine measurements.

Topics

thyroid hormone peripheral conversion, t4 to t3 conversion, reverse t3 elevated levels, thyroid function illness, triiodothyronine production extrathyroidal, thyroid hormone metabolism, low t3 syndrome nonthyroidal illness, thyroid testing interpretation, peripheral thyroid hormone activation, thyroid dysfunction fertility, t3 t4 ratio clinical significance

Cite this article

Schimmel, M., & Utiger, R. D. (1977). Thyroidal and peripheral production of thyroid hormones. Review of recent findings and their clinical implications. *Annals of internal medicine*, *87*(6), 760-768. https://doi.org/10.7326/0003-4819-87-6-760

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