The metabolic effects of hormonal treatment in transgender males: Safety of the testosterone gender-affirming therapy.

Background: Gender dysphoria is characterised by a sense of distress because of discordance between the self-perception of gender identity and the assigned sex. Hormonal treatment of transgender males uses testosterone to induce and preserve masculinisation.

Objective: The study investigated the safety of testosterone therapy in transgender males.

Methods: The present study used a retrospective file review of transgender male subjects who were treated with testosterone (initially transdermal testosterone gel and subsequently parenteral testosterone undecanoate) for at least 18 months and had subsequently achieved a serum testosterone level within the normal range of cisgender male counterparts. Changes in somatometric data and blood biomarkers were investigated.

Results: The mean testosterone serum levels after approximately 18 months of treatment were about 545 ng/dL (SD ± 94 ng/dL). There was a statistically significant rise in body mass index (𝜒d = +1.23 kg/m2) with a reduction in blood glucose (𝜒d = -5.33 mg/dL) as well as statistically significant increases in aspartate transaminase (𝜒d = +4.3 U/L), haemoglobin (𝜒d = +1.72 g/dL), and haematocrit (𝜒d = +4.76%). In contrast, there were no significant changes in the lipidaemic profile of the subjects.

Conclusions: Treatment with testosterone is routinely used for the promotion of virilising physical changes in transgender males. However, the likelihood of adverse effects of continuous treatment is still unclear. This study contributed to the notion that achieving testosterone levels within the target range is a prerequisite for the safety of the gender-affirming treatment.