SFEBES2018 Oral Communications Neuroendocrinology and Reproduction (6 abstracts)
Sex steroids have complex effects: testosterone predominantly regulates trabecular and estradiol, cortical bone1. Studies in transgender individuals use insensitive technology and report conflicting effects2. We hypothesized estradiol therapy will increase cortical volumetric bone mineral density (vBMD) in male-to-female (MtF) individuals and testosterone therapy will increase trabecular vBMD in female-to-male (FtM) individuals.
Aims: To vBMD in transgender individuals receiving cross-sex hormones. HRPQCT was performed in a cross-sectional study MtF and FtM individuals. Unpaired students t-test was used to compare transgender individuals with healthy age and birth-assigned sex matched controls.
Results: Tibial trabecular vBMD (P=0.011) was decreased in MtF compared to control males and cortical vBMD was decreased. Conversely, compared to female controls, FtM individuals receiving testosterone therapy had increased distal tibial trabecular vBMD (P<0.001), with increased trabecular number (P<0.001) and decreased trabecular separation (P=0.008) but no difference in cortical vBMD. Similar findings were seen at the radius.
Distal tibia | MTF (n=39) Mean ± S.D. | Control male (n=57) | P | FTM (n=45) | Control female (n=79) | P |
Cortical vBMD | 841.7±39.4 | 861.5±40.3 | 0.019 | 898.6±34.4 | 892.5±41.3 | 0.398 |
Trabeculae | ||||||
vBMD | 189.7±29.6 | 206.5±32.2 | 0.011 | 202.3±29.6 | 180.5±35.2 | <0.001 |
Thickness | 0.088±0.011 | 0.089±0.015 | 0.615 | 0.093±0.014 | 0.086±0.017 | 0.038 |
Number | 1.82±0.29 | 1.96±0.32 | 0.029 | 1.84±0.25 | 1.78±0.37 | 0.369 |
Separation | 0.477±0.088 | 0.436±0.081 | 0.019 | 0.462±0.068 | 0.500±0.114 | 0.044 |
Total | ||||||
Average vBMD | 297.9±49.0 | 326.3±42.0 | 0.003 | 343.4±50.6 | 308.7±48.5 | <0.001 |
Conclusion: The findings in FtM (increased trabecular vBMD) and MtF individuals (decreased vBMD) support a role for testosterone in building trabecular bone. This study did not confirm a role for estradiol in building cortical bone.