Correlation between serum inhibin B and other indicators of the ovarian function

Objective: To investigate the correlation between the early follicular phase serum inhibin B levels and other indicators of ovarian reserve. Study design: Seventy-four women aged 24-40 years (mean 32) with different infertility etiologies were investigated in the early follicular phase of a spontaneous menstrual cycle. The volume of the ovaries was measured and the total number of follicles <5 mm in size counted by ultrasound. Serum levels of FSH, estradiol (E-2) and inhibin B were measured on the same day. In stepwise regression analysis inhibin B levels were correlated with age, body-mass-index, the ultrasound measurements, cause of infertility, parity, FSH and E-2. Results. FSH, BMI and the number of follicles proved to be statistically significant independent predictive factors for the inhibin B levels, FSH and BMI correlating negatively and the number of follicles positively with inhibin B serum concentrations. Conclusion: The number of small follicles reflect the inhibin B production of the ovaries. BMI being as strong predictive factor of inhibin B levels as FSH could in part explain the impaired likelihood of conceiving in obese patients. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.