RESUMEN
OBJECTIVES: Gender-affirming testosterone therapy is increasingly prescribed among transmasculine adolescents and has been associated with improved mental health outcomes. However, expected and perceived effects of testosterone have not previously been compared in this population. METHODS: We compared desired and reported effects of testosterone in all consecutive transmasculine adolescents followed at a large interdisciplinary gender diversity clinic in North America. Participants received a prescription for testosterone and were first seen between November 2016 and May 2021. Our study was a retrospective audit of case notes. We collected self-reported desired effects prior to initiation of testosterone and self-reported perceived effects from participants' medical records up to 24 months after initiation. The masculinizing effects of testosterone considered in our study were increased body/facial hair, voice deepening/Adam's apple growth, increased muscle mass, clitoromegaly, and body fat redistribution. RESULTS: There were 76 participants included in this study. Mean age at prescription of testosterone was 16.31 years (standard deviation: 0.99â¯years). The effects desired by the greatest proportion of participants prior to initiation were increased body/facial hair (69â¯%) and voice deepening/Adam's apple growth (52â¯%). These same two effects were the most reported by participants, reaching 80â¯% report rates at 12â¯months, and increasing steadily across the 24-month follow-up period. CONCLUSIONS: Our study shows that for most, but not all gender diverse adolescents undergoing testosterone therapy, the most expected physical changes were seen in the first year of gender-affirming treatment. More research and provider education are needed to offer optimal counseling for adolescents undergoing gender-affirming hormone therapy.