Study: Sirolimus Suppresses Testosterone in Male Kidney Transplant Recipients

The immunosuppressive drug Rapamune (sirolimus), which has been shown in animal tests to cause damage to the testicles, appears to significantly suppress testosterone in human male kidney transplant recipients, according to German researchers.

Reporting in the American Journal of Transplantation, the researchers said they compared testosterone, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin concentrations in kidney transplant patients who did or did not receive sirolimus for immunosuppression.

Testosterone is the most important of the male sex hormones, and performs a variety of functions. Luteinizing hormone and follicle-stimulating hormone stimulate the gonads -- in males, the testicles -- and are essential for reproduction. Prolactin is a protein hormone that has no normal function in males.

"We found that testosterone values were lower in 28 sirolimus-treated patients, compared to 28 non-sirolimus-treated controls," the researchers reported. "Furthermore, these patients more commonly had testosterone concentrations that were below our reference value for normal men.

"In contrast, FSH and LH concentrations were higher while prolactin levels were not different," the researchers reported.

"These data are consistent with sirolimus-related testosterone suppression and suggest a need for further studies," the researchers concluded.

Other Sources: American Journal of Transplantation