Reduced spermatic venous inhibin B in varicocele: a paired observational study suggesting possible selective sertoli cell dysfunction

To study specific endocrine alterations in varicocele by directly comparing hormone profiles between affected internal spermatic vein blood and peripheral vein blood, and to explore potential local testicular functional changes that cannot be detected by conventional peripheral indicators. We prospectively enrolled 76 men aged 18–28 years with clinical grade 2–3 unilateral varicocele, normal peripheral inhibin B and testosterone levels, who underwent microsurgical varicocelectomy. Direct intraoperative sampling of affected internal spermatic vein blood compared with peripheral venous blood. Comparison of hormone levels (Inhibin B, testosterone, estradiol, FSH, LH, progesterone) between affected spermatic vein (aINHB, aT, aE2) and peripheral blood (pINHB, pT, pE2). Correlation between aINHB levels and disease severity parameters (clinical grade, ultrasound grade, venous diameter). We observed a significant “hormone dissociation phenomenon”: aINHB level was significantly lower than pINHB (91.4 ± 71.2 pg/mL vs. 217.8 ± 127.6 pg/mL, p < 0.0001), while aT (450.0 ± 1115.0 nmol/l vs. 26.2 ± 8.0 nmol/l, p < 0.0001) and aE2 (276.0 ± 323.3 ng/L vs. 35.2 ± 15.3 ng/L, p < 0.0001) levels were markedly higher in the affected vein. aINHB level showed significant negative correlations with venous diameter ( r = -0.412, p = 0.0052), ultrasound grade ( r = -0.317, p = 0.0427), and clinical grade ( r = -0.286, p = 0.0483). We report reduced inhibin B levels in the affected spermatic vein of varicocele patients despite normal peripheral levels, a finding consistent with a potential model of selective Sertoli cell dysfunction potentially driven by venous hypertension. This observation highlights a limitation of relying solely on peripheral blood testing and suggests that aINHB warrants further evaluation as a candidate marker.