Timing of HT during puberty influences bone development in transgender adolescents
Transgender adolescents treated with gender-affirming hormone therapy early in puberty experience bone development more similar to that of their experienced gender compared with their gender assigned at birth, according to study data.
“The two geometrical parameters we studied, subperiosteal width and endocortical diameter, are regulated by testosterone and estrogen, respectively,” Marianne van der Loos, MD, a researcher and PhD student in endocrinology at Amsterdam University Medical Centers, told Healio. “Based on our findings, the main effect of testosterone and estrogen on periosteal and endocortical bone growth seems to occur during early puberty.”
Van der Loos and colleagues conducted a retrospective study of adolescents who visited the gender clinic of the Amsterdam University Medical Centers from 1987 to 2018. Demographic data and clinical characteristics including puberty stage at the start of HT and the type of HT used, and anthropometry and biochemical variables were obtained from database records. DXA scans were performed as part of routine care. Participants who used a gonadotropin-releasing hormone agonist for at least 6 months, initiated HT before age 18 years and had a DXA scan done within a 6-month range of the start of gonadotropin-releasing hormone agonist, initiation of gender-affirming HT or 2 years since the start of gender-affirming HT were included in the study. Hip structure analysis was performed on DXA scans to assess biomechanical and geometrical parameters of the proximal femur.
The findings were published in the Journal of Bone and Mineral Research.
Of the 322 study participants, 106 were transgender girls and 216 were transgender boys. Researchers performed hip structure analysis on the subperiosteal width and endocortical diameter. The transgender female group had 32 participants analyzed during early puberty, 30 during mid puberty and 44 during late puberty. In the transgender male group, eight participants were analyzed during early puberty, 22 during mid puberty and 186 during late puberty.
Researchers observed marked difference in both the subperiosteal width and endocortical diameter during HT depending on pubertal stage. During early puberty, both transgender boys and transgender girls experienced growth in subperiosteal width and endocortical diameter similar to that of adolescents in their experienced gender. Those who started HT in mid or late puberty had subperiosteal width and endocortical diameter growth similar to cisgender youths in their gender assigned at birth.
“It was exciting to see that there was such a striking difference in change dependent on pubertal stage at start of puberty suppression,” van der Loos said. “This not only teaches us about bone development in the transgender population, but also provides us with more insight into the effects of sex steroids in bone development during the different phases of puberty in the cisgender population.”
According to van der Loos, more research should be done to evaluate the clinical implications of bone development in transgender adolescents.
“To my knowledge there are no studies on, for instance, long-term fracture risk in this particular population,” van der Loos said. “In general, cisgender men are shown to have stronger bones. Speculating, one could think that if transgender women obtain bone geometry similar to that of cisgender women, fracture risk could also equal that of the cisgender women, but further research should address this question.”
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Marianne van der Loos, MD, can be reached at firstname.lastname@example.org.