Inhibin B levels on cycle day 3 to predict the ovulatory response in women with PCOS undergoing ovulation induction via low dose step-up gonadotropin protocol.

BACKGROUND: In this prospective clinical single blind study, we aimed to investigate whether day 3 serum inhibin B levels in women with polycystic ovarian syndrome(PCOS) are of predictive value for the estimation of the ovarian response to gonadotropins. METHODS: Ovulation induction with low dose step-up gonadotropin protocol, starting with 75 IU/day, was performed for 30 cycles on 25 patients with PCOS. Day 3 serum inhibin B, follicle-stimulating hormone(FSH) and estradiol, and midluteal serum progesterone levels were measured during each cycle. The correlations between day 3 inhibin B levels and day 3 FSH, day 3 estradiol and midluteal progesterone measurements, as well as the amount of gonadotropin required to provide an ovulatory cycle were investigated. RESULTS: Five (27.8%) out of 18 cycles with day 3 inhibin levels <50.0 pg/ml; and 11 (91.7%) out of 12 cycles with levels > or = 50.0 pg/ml were ovulatory (chi(2)=9.38, p<0.01). Moreover, day 3 inhibin B levels had statistically significant negative correlation with the gonadotropin used; and significant positive correlation with the midluteal progesterone levels (p<0.05). There wasn't any significant relation between day 3 FSH and estradiol levels with the gonadotropin used and progesterone levels. CONCLUSIONS: It has been observed that as day 3 serum inhibin B levels increased in women with PCOS, the ovulatory response to gonadotropins and the rate of ovulatory cycles increased significantly.