The human corpus luteum secretes 5α-pregnane-3,20-dione

Abstract. A radioimmunoassay for 5α-pregnane-3,20-dione (5α-DHP) in plasma is described. The concentration of 5α-DHP in peripheral plasma during the follicular phase of the menstrual cycle was of the same order of magnitude as that of progesterone (P). During the luteal phase, the plasma 5α-DHP was 8-fold higher than in the follicular phase and about 1/3 of the P concentration. The concentration of 5α-DHP in ovarian venous plasma draining an ovary containing the corpus luteum was 22-fold higher than the concentration in plasma from the contralateral ovarian vein. These results show that the corpus luteum secretes significant amounts of 5α-DHP.