Long-Acting Intramuscular Testosterone Undecanoate for Treatment of Female-to-Male Transgender Individuals

AIM: Testosterone treatment is essential for the induction and maintenance of virilization of female-to-male transsexuals. This study tested the suitability of a novel testosterone preparation for this purpose. METHODS: Parenteral long-acting testosterone undecanoate (TU) was administered to 12 female-to-male transsexuals. Observations were made while subjects received treatment. MAIN OUTCOME MEASURES: Virilization of female-to-male transsexuals and side effects of testosterone administration. RESULTS: The testosterone levels were largely identical to those in hypogonadal men receiving testosterone treatment with TU. There were no side effects. There was a small but significant decrease in plasma cholesterol and low-density lipoprotein, but plasma high-density lipoprotein did not change significantly. Both levels of hemoglobin and hematocrit rose upon administration but remained within the physiological range. CONCLUSIONS: TU is suited for induction of virilization in female-to-male transsexuals without significant side effects.