THE EFFECT OF IODIDE ON THE ACTION OF THYROTROPIN IN THE HYPOPHYSECTOMIZED PATIENT*†

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Abstract
Six previously euthyroid, hypophysectomized patients were given thyrotropin by injection twice daily to stimulate thyroidal uptake and secretion of radioactive iodine. In the presence of a goitrogen-induced block of organic binding of iodine and during continued administration of thyrotropin, iodide produced a significant decrease in the rate of loss of I131 from the thyroid gland in only 1 patient. Propylthiouracil without thyrotropin did not increase the rate of loss of I131 from the thyroid of a hypophysectomized patient. Thyrotropin was used in a dosage of 10 units per day in 4 studies and 2 units per day in 3 studies. The rate of loss was less with 2 units than with 10 units, whether or not iodide was administered. Iodide decreased the rate of loss to the same extent in the one patient in whom it was significantly effective, at both levels of thyrotropin.