Increased sperm nuclear DNA damage in normozoospermic infertile men: a prospective study

Objective: To evaluate levels of sperm nuclear DNA damage in infertile men with normal and abnormal standard semen parameters. Design: Prospective study. Setting: Male infertility clinic. Patient(s): Ninety-two men seeking infertility treatment and 16 fertile volunteers. Intervention(s): Standard semen analysis was performed according to the World Health Organization guidelines. Main Outcome Measure(s): Sperm DNA damage was assessed by sperm chromatin structure assay and the results expressed as %DFI. Result(s): Of the 92 patients, 21 (23%) had normal standard sperm parameters (concentration, motility, and normal sperm forms), while 71 (77%) had an abnormality in one or more of these parameters. The %DFI [median (25th and 75th percentiles)] in infertile men with normal sperm parameters [23 (15, 32)] was significantly higher than fertile donors [15 (11, 20)] (P=.02), but not significantly different from infertile men with abnormal sperm parameters [28 (18, 41)] (P=.27). Conclusion(s): The results of this study indicate that a significant increase in SCSA-defined DNA damage can be found in sperm from infertile men with normal standard sperm parameters. Therefore, sperm DNA damage analysis may reveal a hidden abnormality of sperm DNA in infertile men classified as idiopathic based on apparently normal standard sperm parameters.