Finasteride-induced secondary infertility associated with sperm DNA damage.

OBJECTIVE: To report a case of low-dose finasteride-induced secondary infertility with associated elevated sperm DNA fragmentation index (DFI) and otherwise normal semen parameters.
DESIGN: Case report.
SETTING: University hospital. PATIENT(S): A 48-year-old man on low-dose finasteride and his 37-year-old wife with normal menses and normal gynecologic exam. INTERVENTION(S): Determination of sperm DFI and discontinuation of low-dose finasteride. MAIN OUTCOME MEASURE(S): Sperm DFI. RESULT(S): The sperm DFI done a year earlier was 30%. This value was unchanged when repeated 2 months later. The patient was advised to stop finasteride. Three months after discontinuing the finasteride, the DFI decreased to 21% and subsequent DFI after another 3 months improved to 16.5%. To date, there is still no documented full-term pregnancy or live birth. CONCLUSION(S): The significant reduction in DFI within 3 months of finasteride cessation and continued improvement suggests a causal link between finasteride and sperm DNA damage. We hypothesize that low-dose finasteride may exert a negative influence on sperm DNA integrity, resulting in increased pregnancy losses. We suggest that in infertile men using finasteride, sperm DFI should be measured in addition to semen parameters, and a trial of discontinuation of finasteride may be warranted.