THE DIRECT ESTIMATION OF THE RATE OF THYROID HORMONE FORMATION IN MAN. THE EFFECT OF THE IODIDE ION ON THYROID IODINE UTILIZATION*

Abstract

THE interest of thyroidologists was recently aroused by the demonstration by Wolff and Chaikoff (1) that, with levels of serum iodide higher than 20 to 30 micrograms per cent, organic binding of iodine in the rat thyroid was inhibited. Extension of these observations to man was undertaken in view of the paradox thus presented, i.e., that adequate iodide seemed to prevent hormone formation in the rat and yet failed to control thyrotoxicosis completely or to produce myxedema in man. Although various indirect methods have been used for estimating the rate of hormone formation in man, such as the amount of thyroid necessary to alleviate myxedema, or the urinary excretion of iodine, no direct measurements of this function have been described. It is the purpose of this paper to present a method for the direct estimation of the rate of iodine utilization by the thyroid in man, and to determine the effects of various amounts of iodide on this process. A simple method for calculating the serum iodide is also described.