Seminal level of clusterin in infertile men as a significant biomarker reflecting spermatogenesis

The objective of this study was to assess the impact of seminal clusterin level on spermatogenesis in infertile men. This study included 89 men who visited our clinic due to infertility, consisting of 28, 33, and 28 diagnosed with normospermia, oligozoospermia and nonobstructive azoospermia (NOA) respectively. The seminal clusterin concentrations measured by enzyme-linked immunosorbent assay were 47.9, 28.2 and 18.4 ng ml^-1 in men with normospermia, oligozoospermia and NOA, respectively, with significant differences among these three groups (P < 0.01). Microdissection testicular sperm extraction (MD-TESE) was performed in the 28 men with NOA, and spermatozoon was successfully retrieved from 9. There was a significant correlation between seminal clusterin level and testicular clusterin protein expression evaluated by immunohistochemical staining in these men with NOA (P = 0.026). Of several parameters available before MD-TESE, the univariate analysis identified serum follicle-stimulating hormone (FSH) level <10 IU ml^-1 and seminal clusterin level ≥18 ng ml^-1 as significant predictors of sperm retrieval, and of these, only serum FSH level <10 IU ml^-1 was shown to be independently associated with sperm retrieval in the multivariate analysis. Accordingly, it might be worthy to further evaluate the significance of seminal clusterin level as a biomarker for the assessment of spermatogenic status in infertile men.