PP073 - REGIONAL BODY COMPOSITION IN TRANSGENDER MEN RECEIVING TESTOSTERONE THERAPY: A CROSS-SECTIONAL PILOT STUDY

PP073

REGIONAL BODY COMPOSITION IN TRANSGENDER MEN RECEIVING TESTOSTERONE THERAPY: A CROSS-SECTIONAL PILOT STUDY

Y. Tominaga^1,*, T. Moriwake¹, N. Ozaki¹, T. Kobayashi², S. Katayama¹, S. Nishimura¹, K. Bekku¹, M. Araki¹

¹Urology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, ²Urology, Miyabi Urogyne Clinic, Okayama, Japan

Rationale: Testosterone therapy increases muscle mass in transgender men, but regional data on muscle mass, fat distribution, and basal metabolic rate remain limited. We evaluated whether longer testosterone therapy duration was associated with differences in whole-body and regional body composition.

Methods: This single-center cross-sectional pilot study included 26 transgender men receiving testosterone therapy. Participants were divided into a shorter-duration group and a longer-duration group according to treatment duration (≤48 months, n=13; >48 months, n=13). Body composition was assessed using a multi-frequency bioelectrical impedance analyzer (MC-780A-N, Tanita), including whole-body fat percentage, lean mass, muscle mass, basal metabolic rate, and regional muscle and fat parameters of the upper limbs, lower limbs, and trunk. Grip strength and laboratory results were compared. Group comparisons were performed using the Mann–Whitney U test.

Results: The longer-duration group was significantly older than the shorter-duration group (37.1 ± 7.6 vs 21.5 ± 5.7 years, p < 0.001) and had higher serum creatinine levels (0.83 ± 0.08 vs 0.73 ± 0.10 mg/dL, p = 0.011). The longer-duration group also tended to have higher lean mass, total muscle mass, grip strength, and regional muscle mass of the trunk, upper limbs, and lower limbs. In contrast, whole-body and regional fat percentages did not clearly differ between groups. Basal metabolic rate was similar between groups.

Conclusion: Longer testosterone therapy duration was associated with greater whole-body and regional muscle mass in transgender men, whereas body fat percentage and basal metabolic rate were not clearly different. Regional body composition assessment may provide additional information beyond conventional whole-body measures when evaluating the masculinizing effects of testosterone therapy.

Disclosure of Interest: Y. Tominaga Grant / Research Support from: Tanita Corporation, T. Moriwake: None declared, N. Ozaki: None declared, T. Kobayashi: None declared, S. Katayama: None declared, S. Nishimura: None declared, K. Bekku: None declared, M. Araki: None declared