Effects of Intramuscular Testosterone Undecanoate on Body Composition and Bone Mineral Density in Female-to-Male Transsexuals

Abstract

The most common treatment regimen in female-to-male transsexuals is administration of short-acting testosterone esters intramuscularly every 2 weeks. The aim of this study was to evaluate the effect of long-acting intramuscular testosterone undecanoate on body composition and bone mineral density during cross-sex hormone therapy in female-to-male transsexuals. Forty-five female-to-male transsexuals (FtMs) were treated with injections of testosterone undecanoate 1,000 mg intramuscularly every 12 weeks over 24 months. Body composition, bone mineral density, hormone parameters, and lipids were compared after 12 months and after 24 months with baseline values. Sonographic findings in the ovaries and endometrium, clinical and adverse effects during the study period were recorded. There was a significant increase in lean mass in the FtMs during the study period in comparison with baseline values, whereas no change in BMI, fat mass, and bone mineral density was observed. There was a significant decline in gonadotropins, estradiol, dehydroepiandrosterone sulphate, sex hormone-binding globulin, and high-density lipoprotein, while testosterone and triglyceride levels increased significantly after 12 and 24 months. Ovaries remained unchanged and no noticeable endometrial pathology was observed. No mortality or morbidity was observed during the study period. We observed a cessation of menstrual bleeding, an increase in clitoral growth, libido, body and beard hair growth, deepened voices and decline in breast size. There was a significant increase in hemoglobin, hematocrit, glutamic-pyruvic transaminase, gamma-glutamyl transferase, and an increase in systolic blood pressure during the study period. There was an increase in lean mass during the study period in FtMs treated with testosterone undecanoate. Transsexual patients should be monitored for adverse effects on lipid profiles, blood pressure, and erythrocytosis during intramuscular testosterone undecanoate therapy.