Endocrine Abstracts

JOINT3168

The number of adolescents with gender incongruence seeking for gender-affirming hormone treatments (GAHT) is increasing. There are a few studies about changes in BMI, body composition and bone mineral density (BMD) following treatment, often limited by small sample sizes and heterogeneous therapeutic protocols.

Objective: The aim of our study was to describe BMI, body composition and BMD of transgender adolescents before and after one year of GAHT.

Methods: We conducted a prospective study on 81 transgender adolescents, 34 assigned female at birth (AFAB) and 47 assigned male at birth (AMAB), aged 17 years (14.66-18.2), followed from 2019 to 2024. Anthropometric parameters, body composition, BMD were evaluated before and after one year of GAHT. Body composition was evaluated using Bioelectrical Impedance Analysis (BIA) to determine lean mass (FFM) and fat mass (FM). BMD was assessed using Dual Energy X-ray Absorptiometry (DEXA).

Results: At study entry mean BMI was within normal range in both AFAB (23.77 ± 5.95) and AMAB (22.79 ± 4.99). However, the rate of obesity was higher than in the region general population matched for age (19.7% vs 4.2%) as well as underweight (11% vs 1.4%). AFAB were more frequently obese (26.5%) than AMAB (14.8%) whereas AMAB were more frequently underweight (14.9%) than AFAB (5.9%). After one year of treatment, no significant changes in BMI were observed (AFAB 25.64 ±6.53; AMAB 22.77 ±4.96). Body composition showed significant changes after 1 year of treatment. FFM (%) was significantly reduced (72.77 ± 6.99) vs baseline (79.26 ± 10.14; P = 0.026) and FM (%) increased (27.23 ± 6.99) vs baseline (20,70 ±10.14; P = 0.022) in the AMAB group. In the AFAB group, no significant changes in FFM (%) (68.09 ± 8.20 vs 67.32 ± 8.56) or FM (%) (31.91±8.20 vs 32.68±8.56) were observed. BMD z-score was within normal range in transgender adolescents. AMAB had significantly lower lumbar BMD-z score (-0.82 ±0.85) compared to AFAB (1.17 ± 0.09; P = 0.033). After one year of treatment, no significant changes in BMD-z score were observed in both AMAB (-1. ±0.76) and AFAB (-0.47 ±0.73).

Conclusion: Transgender adolescents have a higher frequency of weight abnormalities before treatment, with a higher frequency of obesity among AMAB, and of underweight among AFAB. After one year GAHT, changes in body composition were observed aligning with the desired gender. No significant changes in BMI or BMD were detected.