ESPE Abstracts (2016) 86 P-P1-343

Evolution of Bone Mass and Body Composition in Gender Dysphoric Adolescents Treated with Progestins to Suppress Endogenous Hormones

Lloyd Tacka,b, Margarita Craena,b, Bruno Lapauwa,b, Stefan Goemaereb, Kaatje Toyeb, Jean-Marc Kaufmana,b, Sara Vandewallea,b, Hans-Georg Zmierczakb & Martine Coolsa,b


aGhent University, Ghent, Belgium; bGhent University Hospital, Ghent, Belgium


Background: In gender dysphoric (GD) adolescents with advanced pubertal development, psychological relief can be attained with progestins, which are much cheaper and easier to administer than GnRHa. Moreover, use of GnRHa has been shown to interfere with pubertal bone mass accrual. To date, few data exist on the effects of progestins on body composition (BC) and bone parameters in this population.

Objective and hypotheses: To explore the effects of pro- and antiandrogenic progestins on muscle strength, BC and bone mass in mid- and late pubertal GD female to male (FtM: lynestrenol) and male to female (MtF: cyproterone acetate) adolescents respectively.

Method: Grip strength, DXA (spine, hip, whole body) and pQCT (radius, tibia) measurements were prospectively performed at start of treatment and before association with cross-sex hormones in 48 GD adolescents (median age: 16.3 years (11.9–18.4 years); 33 FtM; 15 MtF). Statistical analysis: paired Student-t or Wilcoxon signed-ranks test (as appropriate). Z-scores of the biological sex were used. Vitamin D supplementation and calcium-enriched diet was advised in all participants.

Results: Mean treatment duration was 11.5 months. In FtM, lean body mass (LBM) and grip strength increased. Waist and hip circumference increased, waist-hip ratio (WHR) remained unaltered. Bone mineral content (BMC), density (BMD), trabecular and cortical bone increased at all sites; mean BMD Z-scores did not change significantly (WB: −0.813 to −0.813). In MtF, LBM and WHR decreased, fat mass increased; grip strength remained constant. Bone area and BMC increased; however, BMD remained constant and BMD Z-scores decreased (WB: −1.280 to −1.587, P=0.017). Trabecular bone decreased, cortical bone increased.

Conclusion: Treatment with pro- and anti-androgenic progestins results in body composition changes towards the desired sex. Lynestrenol did not affect bone mass accrual, while Cyproterone acetate was associated with a stagnating bone mass accrual, similar to GnRHa. Preventive measures are warranted, especially in MtF adolescents.