EFFECT OF POSTMENOPAUSAL ESTROGEN REPLACEMENT ON CIRCULATING ANDROGENS

Objective: To determine the effect of estrogen replacement therapy (ER T) on serum androgen levels in postmenopausal women. Methods: We measu red serum dehydroepiandrosterone (DHEA), DHEA-sulfate, testosterone, e stradiol (E2), LH, FSH, and sex hormone binding globulin in 8:00 AM fa sting serum samples from a previous randomized, blinded, placebo-contr olled crossover study in which 28 postmenopausal women (27 naturally m enopausal) were given 2 mg/day of oral micronized estradiol. The treat ment arms were 12 weeks with a 6-week washout. Results: Estrogen repla cement therapy raised mean (+/- standard error of the mean [SEM]) seru m E2 from 8.7 +/- 1.0 to 117 +/- 18.7 pg/mL (P <.001 from baseline). C oncurrently, mean (+/-SEM) DHEA-sulfate fell from 67.3 +/- 9.6 to 52.1 +/- 6.4 mu g/dL (P <.001), and mean (+/-SEM) testosterone fell from 1 6.1 +/- 2.4 to 9.4 +/- 1.4 ng/dL (P =.006). Both FSH and LH declined s ignificantly. Sex hormone binding globulin increased by 160% with ERT (P <.001). Conclusion: Menopausal ERT decreases serum androgen levels, decreasing DHEA-sulfate and testosterone by 23% and 42%, respectively . Whereas the decline in testosterone is likely due to decreased LH-dr iven ovarian stromal steroidogenesis, the declining levels of DHEA-sul fate also may imply a direct adrenal effect of estrogen. Bioavailable testosterone likely is reduced even more profoundly because sex hormon e binding globulin is increased 160% by estrogen. Thus, menopausal ERT may induce relative ovarian and adrenal androgen deficiency, creating a rationale for concurrent physiologic androgen replacement. (C) 1997 by The American College of Obstetricians and Gynecologists.