Evaluation of serum inhibin B and inhibin B/FSH ratio in the diagnosis of non-obstructive azoospermia and oligozoospermia

Objectives: Infertility affects approximately 15 % of couples globally, with 50 % cases of male factor infertility. Precise assessment of spermatogenesis is essential for evaluating male infertility. Recent studies suggest serum inhibin B as a promising biomarker for testicular function. This study aims to evaluate the diagnostic utility of serum inhibin B in predicting male infertility, particularly focusing on its relationship with sperm count. Methods: A cross-sectional study was conducted on 80 adult men (mean age 31.4 ± 6.89 years) presenting with infertility at gynecology and urology outpatient departments. Semen analysis was performed following WHO (2010) guidelines, and serum inhibin B levels were quantified. The correlation between serum inhibin B levels and sperm parameters was assessed using Pearson’s correlation test. Receiver operating characteristic (ROC) curve analysis was employed to evaluate the diagnostic accuracy of serum inhibin B and the inhibin B/FSH ratio for non-obstructive azoospermia (NOA) and oligozoospermia. Results: A significant positive correlation was observed between serum inhibin B and sperm count (r=0.94, p<0.001). ROC analysis demonstrated that the inhibin B/FSH ratio had the highest diagnostic accuracy for NOA and oligozoospermia (AUC=0.986), with sensitivity of 100 % and specificity of 91.67 %. Serum inhibin B alone also showed high diagnostic value (AUC=0.965 for NOA and 0.969 for oligozoospermia). Conclusions: Serum inhibin B is a reliable biomarker for assessing male infertility, particularly in evaluating spermatogenic function. The inhibin B/FSH ratio provides superior diagnostic accuracy for NOA and oligozoospermia, offering valuable clinical utility in male infertility diagnosis.