Response of the thyroid gland to thiocyanate and thyrotropin.

Abstract

ABSTRACT In order to determine whether inhibition of the thyroidal iodide “trap” by thiocyanate was dependent only upon the serum concentration of the ion, thyroid function was studied in 15 euthyroid and 3 hyperthyroid subjects before and during administration of potassium thiocyanate. Serum thiocyanate levels were correlated with thyroidal radioiodine (I131) uptakes, and thyrotropin was administered to 8 euthyroid and 3 hyperthyroid subjects while the thyroid gland was under the inhibitory influence of thiocyanate. In euthyroid subjects complete interference with thyroidal I131 accumulation did not occur readily at serum thiocyanate levels below 5 mg. per 100 ml. In hyperthyroid subjects, thyroidal I131 uptake proved impossible to inhibit completely, regardless of the magnitude of the serum thiocyanate level. In euthyroid subjects, at all serum thiocyanate concentrations, thyrotropin (20 to 30 U.S.P. units) produced measurable increments in the collection of radioiodine by the thyroid. In contrast, the ...