Endocrine Abstracts

Introduction: Intramuscular Testosterone Undecanoate (TU, Nebido^®) has become available in November 2004 in Europe for the treatment of male hypogonadism. Continuous physiological hormone replacement is necessary for transgender patients, both prior to the gender adjustment operation and for the remainder of the individual’s lifetime. The administration of long-acting TU therefore stood to reason as part of cross-gender testosterone therapy for female-to-male transgender patients.

Patients and methods: Beginning in November 2004, a total of 13 transsexual patients (median age 33 years ±6×±S.E.) have been treated with TU. The first injection interval was six weeks. Subsequent injections were administered in 12-weekly intervals. The diagnosis was made in close cooperation with the sexual therapists in compliance with applicable standards. Close-meshed laboratory controls (Hb, Hk, total testosterone, SHBG, dihydrotestosterone, FSH, estriol, estradiol) were carried out both before and during therapy.

Results: 12 out of 13 patients are continuing TU therapy to date. In the case of one patient, a pronounced needle phobia led to discontinuation of TU treatment. Total testosterone levels increased from 0.5 ng/ml ±0.2 prior initiation of cross-gender therapy to 4.5 ng/ml (±1; x±S.E.) after 6 weeks and to 6.5 ng/ml (±1.2; x±S.E.) after 18 weeks of treatment with TU [normal male reference range 2.4–8.3 ng/ml]. Undesirable side effects have not been observed. We were able to prolong the application time period for one patient from 12 to 14 weeks.

Conclusions: TU is a safe and effective therapy for female-to-male transgender individuals, maintaining testosterone levels within physiological limits. The three-month intervals make TU a convenient option for the patient within the framework of a cross-gender hormone therapy. Our results confirm the positive experiences that have been reported previously for the application of TU in hypogonadal men. Monitoring and individualisation of the application interval under therapy are necessary.