Comparison of Follicle-Stimulating-Hormone-Stimulated Dimeric Inhibin and Estradiol Responses as Indicators of Granulosa Cell Function in Polycystic Ovary Syndrome and Normal Women

Abstract

Follicular phase secretion of inhibin B, like that of estradiol (E(2)), correlates with the quantity and quality of developing follicles. However, it has not been established whether inhibin B responses to gonadotropin stimulation parallel those of E(2) as a reflection of granulosa cell functional capacity. Our objective was to determine whether inhibin B responses to FSH stimulation are similar to those of E(2) in women with polycystic ovary syndrome (PCOS) and normal women. We conducted a prospective study to compare ovarian responses in two groups of women at a general clinical research center in a tertiary academic medical center. Women with PCOS, 18-35 yr (n = 19), and normal ovulatory controls, 18-35 yr (n = 7), were recruited for study. Serum samples were measured over a 24-h period after an iv injection of recombinant human FSH, 150 IU. Serum E(2), inhibin A, and inhibin B responses after FSH administration were assessed. In PCOS women, the 24-h production of inhibin B and E(2) after FSH was significantly greater than that of normal controls. Within the PCOS group, the fold change in inhibin B was significantly greater than that of E(2). Inhibin A responses between groups were similar and of markedly lower magnitude. FSH-stimulated inhibin B responses may be employed to assess the functional capacity of granulosa cells in PCOS and normal women.