Chen H, et al. - In this prospective study involving 29 transwomen and 30 transmen, researchers examined the impacts of hormonal treatment (HT) on vitamin D-binding protein (DBP), and total, bioavailable, and free 25(OH)D, and evaluated if total 25(OH)D is bioavailable and free 25(OH)D. In transwomen, DBP tended to increase, but in transmen did not change. In transwomen and transmen, HT did not affect free 25(OH)D, total 25(OH)D and bioavailable 25(OH)D concentrations. Since a total of 25(OH)D is bioavailable and free of 25(OH)D well, HT does not interfere with the assessment of vitamin D status in transgender people.