Testosterone undecanoate and testosterone enanthate injections are both effective and safe in transmen over 5 years of administration.

OBJECTIVE: To retrospectively evaluate and compare safety and efficacy of short and long-acting testosterone (T) parenteral formulations over 5 years in transmen. DESIGN AND METHODS: Fifty transmen between 21 and 42 years of age were enrolled. Twenty-five received T undecanoate 1000 mg IM (weeks 0 and 6 then every 12-16 weeks), and 25 received T enanthate 250 mg IM (every 3-4 weeks). Hormonal and biochemical parameters, anthropometric characteristics and blood pressure were assessed at baseline and then every 12 months. Body composition was evaluated at baseline and then after 1, 3 and 5 years of T treatment. Global satisfaction was assessed at baseline and after 1 and 5 years. RESULTS: Both T formulations led to amenorrhoea in all subjects within 1 year of T administration. Both T treatments led to a similar increase in haemoglobin and haematocrit which always remained within the physiological range. T administration was associated with an increase in total cholesterol, low-density lipoprotein cholesterol and triglycerides and a slight reduction in high-density lipoprotein cholesterol. Coagulative and glucidic profiles and blood pressure did not change significantly in either group. Body weight and BMI showed a slight but not significant increase in both groups, while lean mass rose significantly in both groups. Global satisfaction was increased at years 1 and 5 in both groups. CONCLUSIONS: Preliminary results from this pilot study suggest that administration of either TU or TE for 5 years in young transmen is both effective and safe. Our study presents the longest follow-up published so far reporting no adverse events and these data are consistent with previous reports with a shorter follow-up.