Ovarian response to follicle-stimulating hormone in women with polycystic ovary syndrome is diminished compared to ovulatory controls.

Abstract

The mechanisms underlying ovarian dysfunction in polycystic ovary syndrome (PCOS) have not been definitively established. Our objective was to perform a detailed examination of ovarian responses to recombinant follicle-stimulating hormone (rFSH) in women with PCOS and controls. This prospective, crossover, dose-response study included three rFSH stimulation periods. Each stimulation period involved three consecutive, daily, subcutaneous injections of rFSH administered at a single dose. Low, medium and high rFSH doses were weight-adjusted, corresponding to 0.5, 1.1 and 2.2 IU/kg/d, respectively. Stimulation periods occurred in randomized order and were separated by 8-week washouts. Thirty participants (8 PCOS and 22 controls) were studied. PCOS was defined by oligomenorrhea and clinical or biochemical androgen excess, excluding other aetiologies of ovulatory dysfunction. Blood samples were obtained for hormone measurements before and 24 h after each rFSH injection. Participants with PCOS had significantly greater body mass index, antral follicle count and circulating testosterone, anti-mullerian hormone (AMH)and luteinizing hormone concentrations compared with controls participants. Baseline estradiol (E2) concentrations were similar in both groups. At the lowest dose of rFSH, PCOS participants did not demonstrate E2 increments, whereas a significant increase occurred in controls. rFSH-induced E2 production per follicle was significantly reduced in PCOS participants compared with controls at all rFSH doses. Increasing T and decreasing AMH concentrations were associated with augmented E2 production per follicle. Women with PCOS exhibited diminished initial E2 responses to rFSH compared with controls. These findings suggest that the mechanism of anovulation in PCOS may involve altered ovarian response to gonadotropins.