Blood Production and Ovarian Secretion Rates of Estradiol-17β and Estrone in Women Throughout the Menstrual Cycle

Abstract

The dynamics of estrogen secretion and production were studied using isotope dilution techniques combined with direct sampling of ovarian venous blood in 11 endocrinologically normal women at different stages of the menstrual cycle. The mean metabolic clearance rate (±SE) of estradiol (1202 ± 55 1 plasma/24 hr) and conversion ratio of estradiol to estrone (0.105 ± 0.010) were similar to those described in the literature. The blood production rate of estradiol (μg/24 hr) increased from 63 during menstruation to reach peaks of 394 immediately prior to ovulation and 337 during the midluteal phase. Analysis of ovarian venous plasma indicated that over 95% of estradiol entering the blood originated from either the preovulatory follicle or the corpus luteum. The ovarian secretion of estrone fluctuated in a similar manner to that of the blood production rate of estradiol to reach a maximum of not more than 120 μg/24 hr at midcycle. The ovarian blood flow (±SE) was 20.7 ± 5.7 ml/min (n = 6). The concentration of estradiol in follicular fluid was much higher than that of estrone and reached a maximum value (350 μg/100 ml) 2 days prior to ovulation.