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.