INFLUENCE OF ESTROGEN ON THYROID FUNCTION*

Abstract
The concn. of serum precipitable I (SPI), increases in men or women during the admn. of estrogen. A "leveling off in the increments is usually observed by the 3d or 4th week. Normal function of the pituitary and thyroid are necessary for the reaction to occur. The SPI falls to control values when the estrogen is discontinued. Data are presented to indicate that the increments in SPI are due to an increase in activity of the thyroid, at least for a period of time, and not due to an altered rate of disposal of thyroid hormone.