INFLUENCE OF ESTROGEN ON THYROID FUNCTION*

Abstract

THAT important relationships exist between thyroidal and gonadal function has long been suspected but, especially in man, these relationships have been only incompletely denned. Although attempts have been made to show that clinical or “subclinical” alterations in thyroid function cause menstrual or obstetric abnormalities, many studies have suffered from a lack of precise methods of evaluating thyroid activity. Also, many studies have been further hampered by a lack of data on the possible influence of ovarian hormones themselves on thyroid function or on the responsiveness of tissue to the circulating thyroid hormone. The studies to be reported were undertaken to investigate the influence of estrogen on the activity on the thyroid. Preliminary investigations in this department (1) indicated that the administration of estrogen led to a rise in the serum precipitable iodine (SPI). These studies are now extended and an effort is made to elucidate the mechanism of the estrogen-induced rise in the SPI.