Transwomen and bone mineral density: a cross-sectional study in Brazilian population

Transgender individuals submitted to hormone or surgical treatment may have alterations in their bone metabolism as these elements are important players in bone remodeling. We aimed to study bone mineral density (BMD) and body composition in transwomen undergoing cross-sex hormonal treatment (CSHT) from Brazil for over 3 years, comparing them with female and male controls.

93 individuals (31 transwomen, 31 females and 31 males paired for age and body mass index) were studied for bone mass, and body composition by densitometry (by DXA). Epidemiological and clinical data were collected through direct questioning.

Low bone mass (T score ≤2) was found in 12.9% of transwomen; in 3.2% of females and 3.3% of males. Transwomen individuals had lower spine Z score (0.26 ± 1.42 vs 0.50 ± 1.19) and femur Z score (-0.41 ± 0.95 vs 0.29 ± 1.04) than females. They had lower total femur Z score than males (-0.41 ± 0.95 vs 0.20 ± 0.83). Lean mass values correlated positively with total femur BMD (ρ = 0.40; 95% confidence interval = 0.009-0.68; p = 0.04) and BMD in femoral neck (ρ = 0.48; 95% confidence interval = 0.11-0.74; p = 0.01) but neither the type of therapy received nor the time that they were used, impacted bone mass.

Low BMD is found frequently in transwomen and it is correlated with lean body mass.

There are few studies of the effects of hormone therapy on the bones and muscles of transwomen. This study demonstrated that significant changes occur, and that the population studied needs greater care in musculoskeletal health.