Early Effects of Testosterone Initiation on Body Mass Index in Transmasculine Adolescents

Abstract Purpose Increasing numbers of transgender youth are receiving hormone therapy in accordance with national and international guidelines. This study sought to determine the effect of testosterone on body mass index (BMI) z-score in transmasculine adolescents at 6 and 12 months after initiation. Methods A retrospective chart review collected anthropomorphic data on transmasculine adolescents, aged 13 to 19 years, before and during testosterone use. These measurements were used to create a linear mixed model to explore the change in BMI z-score after initiating testosterone. Results The increase in BMI z-score in transmasculine adolescents was significantly higher after six months of testosterone use, but there was no significant change between baseline and 12 months. Conclusions Additional study is needed to understand the full short- and long-term impact of testosterone use on BMI z-score in transmasculine adolescents to provide appropriate informed consent and develop interventions to improve health outcomes.