Basal and day 12 inhibin concentrations in the prediction of ovarian response to gonadotrophins in women with PCOS

BACKGROUND: In this study, we aimed to investigate whether basal and day 12 serum total inhibin concentrations in women with polycystic ovarian syndrome (PCOS) were of predictive value for the estimation of the ovarian response to gonadotrophins. METHODS: Ovulation induction with a very low dose gonadotrophin protocol, starting with 37.5 IU/day, was performed for 40 cycles on 35 patients with PCOS. Day 3 (basal) serum total inhibin, FSH and oestradiol concentrations; day 12 dominant follicle diameter, inhibin and oestradiol concentrations and midluteal serum progesterone concentrations were measured during the 40 cycles. The correlations between basal and day 12 inhibin concentrations and some critical ovulation monitoring parameters were investigated. RESULTS: Ovulation was obtained in 14 out of 40 cycles: 21% of cycles with basal inhibin <1.0 IU/ml; 33.3% of cycles with basal inhibin between 1.0-1.9 IU/ml; and 83.3% of those with inhibin concentrations > or =2 IU/ml were ovulatory (P < 0.05). Ovulation was achieved in 91.6% of the cycles with a day 12 inhibin concentration > or =4 IU/ml. CONCLUSIONS: Basal inhibin concentrations may determine poor and good responders to ovulation induction with very low dose gonadotrophin protocol in patients with PCOS. The day 12 inhibin concentration was found to be a more sensitive parameter than the oestradiol concentration in the prediction of follicular maturation.