Safety aspects of 36 months of administration of long-acting intramuscular testosterone undecanoate for treatment of female-to-male transgender individuals.

DESIGN: Testosterone treatment is essential for the induction and maintenance of virilization of female-to-male (FTM) transsexuals. Aim To test the safety of a novel testosterone preparation for this purpose.
METHODS: Parenteral long-acting testosterone undecanoate (TU) was administered to 17 FTM transsexuals over 36 months. Observations were made while subjects received treatment.
RESULTS: Serum testosterone rose from 0.50+/-0.25 to 6.2+/-1.3 ng/ml at 6 months and remained stable thereafter. The testosterone profiles were largely identical with those in hypogonadal receiving TU. There were no side effects. Over the 36 months of the study, there was a small but significant decrease in plasma cholesterol (from 218+/-47 to 188+/-42 mg/dl) and low-density lipoprotein-cholesterol (from 139+/-48 to 139+/-48 mg/dl), while plasma levels of high-density lipoprotein-cholesterol and triglycerides did not change significantly. Liver enzymes did not change during treatment. There was an increase of both levels in hemoglobin (from 13.6+/-1.2 to 16.0+/-1.5 g/dl) and hematocrit (from 41+/-4 to 46+/-4) upon administration but they remained almost without exception within the physiological range. No special measures were needed. Breast and gonads/internal genitalia did not show pathological changes over the observation period.
CONCLUSION: This study reports that TU is suited for induction of virilization in FTM transsexuals without significant side effects over a longer term.