Body Composition Measurement by Bioimpedance: A Simple Tool or Tailoring Gender-affirming Care in Transgender Adolescents
2The Nutrition and Dietetics Unit, Tel Aviv Sourasky Medical Center
3The Psychological Services, Tel Aviv Sourasky Medical Center
Background:
In transgender adolescents, estrogen and testosterone dose are based on weight and body surface area (BSA) respectively. Testosterone requirements in transmales are associated with increased BMI, whereas, in transfemales the effect of BMI on estradiol dose requirements is inconclusive. Body composition assessment may provide a more nuanced approach to customize gender-affirming hormone care.
Aim:
To explore the relationship between body composition parameters and hormone levels in transgender adolescents on gender-affirming hormone therapy.
Methods:
Seventy-nine transgender adolescents (54 transmales) treated in the Israeli Pediatric Gender Clinic. Body composition was assessed by bioelectrical impedance analysis (BIA, Tanita MC-780 MA). Outcome measures: estradiol and testosterone levels in correlation with indices of adiposity (total/truncal fat percentage) and muscle (muscle-to-fat ratio).
Results:
Weight distribution differed between genders (p=0.002) with a greater proportion of underweight in transfemales (32% vs 3.7%) and a greater proportion of overweight/obese in transmales (31.5% vs 20%). Testosterone peak levels in transmales were negatively correlated with total and truncal fat percentage (r=-0.48 and r=-0.41 p<0.05,respectively) sarcopenic index (r=-0.58,p<0.01) and BSA (r=-0.62,p<0.01) and positively correlated with muscle-to-fat ratio z-score (r=0.33,p=0.03). Testosterone through levels negatively correlated with sarcopenic index (r=-0.35,p=0.017) and BSA (r=-0.28,p=0.028). In transgender females, estradiol levels did not significantly correlate with body composition parameters.
Conclusion:
Body fat and the balance between muscle and fat, as demonstrated by BIA, correlates with testosterone peak levels in transmale adolescents on gender-affirming treatment and may help dose adjustment. This is of importance as weight status and body composition varies greatly in this population.
