Gender-Affirming Hormonal Treatment and Long-Term Bone Safety
Clinicians should assess BMD only when risk factors for osteoporosis exist in trans women and trans men.
According to study results published in the Journal of Bone and Mineral Research, gender-affirming hormonal treatment does not negatively affect bone mineral density (BMD) in transgender people. As such, regular assessment of BMD during hormonal treatment is unnecessary.
Researchers conducted this study to examine the effects of gender-affirming hormonal treatment on BMD during the first 10 years of treatment. Treatment in trans men consisted of oral, transdermal, or intramuscular testosterone. For trans women, treatment consisted of oral or transdermal estrogens, often including antiandrogens until gonadectomy. In total, 711 trans women (median age, 35 years) and 543 trans men (median age, 25 years) received dual-energy X-ray absorptiometry scans at baseline, as well as at 2, 5, and 10 years, and were assessed for BMD of the lumbar spine, total hip, and femoral neck before treatment initiation and approximately every 2 to 5 years thereafter.
Before estradiol-based treatment, 21.9% of included transwomen had low lumbar spine BMD for their age (z score, <-2.0). After 10 years of treatment, average lumbar spine BMD did not significantly change (+0.006 g/cm2), but average lumbar spine z score increased by 0.22. The same was true for trans men who underwent testosterone-based treatment, 4.3% of whom had low BMD for their age at baseline. After 10 years of treatment, lumbar spine BMD only increased an average of 0.008 g/cm2, but lumbar spine z score increased by an average of 0.34.
In the small number of patients assessed for total hip and femoral neck BMD at 5 and 10 years, there were no significant changes for transwomen or transmen.
Several limitations were noted, including lack of long-term clinical data on, for example, smoking habits and body weight because of the study's retrospective nature, as well as an absence of a control group.
"[C]linicians should assess BMD only when risk factors for osteoporosis [exist], and especially in those who stop [hormonal treatment] after gonadectomy," said the researchers. "For transwomen, testing BMD at baseline should be considered based on the high prevalence of low bone density at baseline, whereas this does not seem necessary for transmen."
Wiepjes CM, de Jongh RT, de Blok CJM, et al. Bone safety during the first ten years of gender-affirming hormonal treatment in transwomen and transmen [published online December 7, 2018]. J Bone Min Res. doi:10.1002/jbmr.3612