Testosterone-Binding Levels in the Serum of Women During the Normal Menstrual Cycle, Pregnancy, and the Post-partum Period

Abstract

The testosterone-binding level (or activity) in human serum, as determined by our technique based on the principle of equilibrium dialysis but utilizing Sephadex G-25, remained low and relatively constant during the normal menstrual cycle. It rose steeply, however, during the first trimester of pregnancy and gradually thereafter, attaining at term a level about 2–3 times that obtained in the nonpregnant state; a rapid return to nonpregnancy levels occurred after delivery. These observations suggest that the testosterone-binding level is directly related to endogenous steroid sex hormone production; estrogen may be particularly important in this respect since elevated testosterone-binding levels were also observed in men with prostatic cancer receiving estrogen therapy.