Introduction: Gender differences in insulin resistance, body composition and lipid profile are well known and related to sex steroid hormones. In this study, we examine the metabolic profile of transsexual persons undergoing drastic sex steroid changes, during the first year of hormonal therapy.
Design: This research is part of a prospective intervention study conducted in several European gender teams (Ghent, Oslo, Amsterdam, and Florence).
Subjects: We present the data of Ghent gender team with 56 male-to-female (transwomen) and 24 female-to-male (transmen) transsexual persons, of whom 36 and 13 respectively have been in follow-up for 1 year of cross-sex hormonal therapy (CSH).
Methods: Standardized treatment regimens were used with oestradiolvalerate, 4 mg daily (or transdermal 100 μg/3 days for patients older than 45 years old) combined with cyproterone acetate 50 mg daily for transwomen and testosterone undecanoate i.m. 1000 mg/12 weeks for transmen. A glucose tolerance test was performed, HOMA-IR was calculated, waist-hip-ratio, lipids, total body fat and lean mass (dual X-ray absorptiometry), regional muscle mass and subcutaneous fat mass at the forearm and calf (peripheral quantitative CT-scan) and grip strength (hand dynamometer) were measured, before and after 1 year CSH.
Results: In transwomen, anti-androgens and oestrogens induced a higher total and subcutaneous fat mass and lower lean mass, muscle mass and strength and a lower waist-hip ratio (all P≤0.001). Fasting insulin and HOMA-IR were higher after 1 year of CSH. HDL, LDL, and triglycerides decreased after 1 year (all P≤0.04).
Transmen gained lean body mass and muscle mass and strength and lost total body fat (all P<0.001) as well as subcutaneous fat after 1 year of testosterone (P=0.019). A decrease in HDL and increase in triglycerides was observed (P≤0.015).
Conclusions: Oestrogen and anti-androgens in transwomen lead to more fat mass with a gynoid pattern of distribution. Testosterone treatment induces a less favourable lipid profile in transmen.