THE INFLUENCE OF ADRENAL AND GONADAL STEROIDS ON THE UPTAKE OF IODINE BY THE THYROID GLAND

IN RECENT years there has been a renewal of interest in the relationship between the hormones of the thyroid and the adrenal cortex. It has been generally established that cortisone and ACTH have a depressing action on thyroid function in man, as measured by the thyroid uptake of radioiodine (1–4) and by the plasma organic iodine level (2, 5). The thyroid inhibitory action of ACTH and cortisone has also been studied in the rat (6–9). There are a few reports not in accord with the concept of cortical hormone inhibition of the thyroid (10, 11). There has been relatively little reported on the effect of other steroid hormones on thyroid function, especially in man, and the reported results are conflicting. Desoxycorticosterone has been claimed to have no effect on the thyroid of the intact rat (10) but has also been shown by others to increase the thyroid iodine concentration in both adrenalectomized (12) and normal rats (13), as well as in guinea pigs (14). Evidence has been presented in favor of an ovarian-thyroid antagonism (15) but both ovariectomy and estrogen administration have failed to influence the ability of the thyroid to take up radioiodine (16). However, Money et at. (6) have reported increased collections of iodine by the rat thyroid following treatment with estrone, progesterone and testosterone and decreased collections after estradiol and pregnenolone.