Dynamics of bioactive follicle-stimulating hormone secretion in women with polycystic ovary syndrome: effects of estradiol and progesterone

Objective: To determine the nature of bioactive FSH secretion in anovulatory women with polycystic ovary syndrome (PCOS) and its modulation by luteal levels of E 2 and P. Design: Interventional and observational study. Setting: Academic clinical research center. Patient(s): Five patients with PCOS. Intervention(s): Treatment for 21 days with luteal levels of E 2 and P. Main Outcome Measures: Serum levels of immunoreactive LH, immunoreactive FSH, bioreactive FSH, and the FSH isoform distribution pattern. Blood was sampled frequently and GnRH testing was done on day 0 (before treatment), days 10 and 20 (during treatment), and day 28 (7 days after treatment). Result(s): Treatment with E 2 and P suppressed circulating immunoreactive LH and immunoreactive FSH but not bioreactive FSH. Anovulatory women with PCOS showed a predominantly acidic pattern of FSH isoform distribution. Treatment with E 2 and P shifted the distribution profile of FSH isoforms to the less acidic. After cessation of E 2 –P treatment, FSH reverted to its pretreatment pattern of distribution. Conclusion(s): Resumption of follicular growth after luteal replacement of E 2 and P in anovulatory women with PCOS may be related to the reduction in the elevated LH/FSH ratio and accompanying changes in the FSH signal.