The effect of sirolimus on sex hormone levels of male renal transplant recipients

Background: It is unclear whether sirolimus, a newer immunosuppressive agent, widely used in renal transplantation, affects male sex hormone levels or sexual function. Methods: Sex hormone profiles in male renal transplant recipients were obtained and compared between a sirolimus-treated group and a group not on sirolimus in a cross-sectional study. Both groups also completed a sexual dysfunction questionnaire. Results: Sixty-six subjects were evaluated, 32 in the sirolimus group and 34 in the control group. Total testosterone level was significantly lower in the sirolimus group than the control group (393.3 ± 188 vs. 537.4 ± 232 pg/mL; p = 0.08) while follicle stimulating hormone and luteinizing hormone levels were significantly higher in the sirolimus group (12.8 ± 14 vs. 6.0 ± 5, p = 0.013; 10.9 ± 14 vs. 4.7 ± 4, p = 0.018, respectively). There was a significant negative correlation between 24-h sirolimus trough and total testosterone levels (p < 0.03). By multiple regression analysis, use of sirolimus was independently associated with decreased total testosterone level. There was no significant difference in subjective sexual dysfunction as assessed by questionnaire scores between the two groups. There was no correlation between questionnaire scores and total testosterone level. Conclusion: Sirolimus is associated with decreased total testosterone levels in male renal transplant recipients. It is unclear whether sirolimus may affect other aspects of sexual function.