1. Synthesis of thyroid hormone and pathophysiology of medical management
Synthesis of thyroid hormone and pathophysiology of medical management. PTU inhibits peroxidase, which catalyzes (1) the oxidation of I− to I2 and (2) 2 coupling reactions to create T3 and T4. Methimazole inhibits the ability of iodine to combine with tyrosine (on TG). Iodides and glucocorticoids inhibit proteolysis of TG-bound T3 and T4, thus inhibiting the release of T3/T4 into blood. PTU and glucocorticoids also inhibit conversion of T4 to T3 in the periphery. TSH binds its receptor to stimulate synthesis and secretion of T3/T4 by stimulating endocytosis of TG/T3/T4 complex, which, until stimulation, is stored in the follicular lumen. I− = iodide; I2 = iodine; PTU, propylthiouracil; T3, triiodothyronine; T4, thyroxine; TG, thyroglobulin; TSH, thyroid-stimulating hormone. (Adapted from Costanzo L. BRS Physiology. 4th ed. Baltimore, MD: Lippincott Williams & Wilkins; 2007.) (Figure adapted by Dr. Erin Meschter.)
Source: Thyroid and Other Endocrine Emergencies, Obstetric Intensive Care Manual, 4e
Citation: Foley MR, Strong, Jr. TH, Garite TJ. Obstetric Intensive Care Manual, 4e; 2015 Available at: Accessed: November 05, 2017
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