Objective: To assess the role of inhibin B in the evaluation of male factor infertility.
Design: Prospective study.
Setting: Reproductive endocrinology clinic.
Patient(s): Seventy-five patients with infertility problems (mean age 31.2 +/- 7.5 years) and 12 controls (32.1 +/- 8.8 years) with proven fertility.
Intervention(s): None.
Main outcome measure(s): Semen analysis was performed according to World Health Organization guidelines. Testicular volume was assessed with the Prader's orchidometer. Serum levels of inhibin B (pg/mL), LH (mIU/mL), FSH (mIU/mL), prolactin (micro IU/mL), and testosterone (nmol/L) were assessed.
Result(s): The mean +/- SEM inhibin B and testosterone levels were significantly lower in the patients than in the controls (inhibin B: 116.4 +/- 11.7 vs. 181.2 +/- 20.9, P=.008; testosterone: 13.6 +/- 0.9 vs. 25.1 +/- 2.9, P=.008). In general, sperm count and testicular volume in the patients were significantly and positively correlated with inhibin B (sperm count: r = 0.476, P<.0001; testicular volume, right: r = 0.57, P=.0001; left: r = 0.53, P=.0001); the inhibin B-FSH index was negatively correlated with FSH. Inhibin B was more strongly correlated with testicular volume and semen parameters than FSH. Inhibin B in the patients was negatively correlated with FSH (r = -0.723, P=.0001) and LH (r = -0.52, P=.0001) and was positively correlated with testosterone (r = 0.4, P=.0013).
Conclusion(s): Inhibin B measurement is a better marker of fertility status than FSH and LH. Concentration of inhibin B in patients with infertility may provide useful information on spermatogenesis and possibly serve as a more direct marker of spermatogenesis than FSH.