Bone Mass, Bone Geometry, and Body Composition in Female-to-Male Transsexual Persons after Long-Term Cross-Sex Hormonal Therapy

• Published in: The journal of clinical endocrinology and metabolism Vol. 97; no. 7; pp. 2503 - 2511
• Main Authors: Van Caenegem, E, Wierckx, K, Taes, Y, Dedecker, D, Van de Peer, F, Toye, K, Kaufman, J.-M, T'Sjoen, G
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Endocrine Society 01.07.2012; Copyright by The Endocrine Society
• Subjects: Absorptiometry, Photon; Adult; Biological and medical sciences; Body Composition - physiology; Bone and Bones - anatomy & histology; Bone and Bones - diagnostic imaging; Bone Density - physiology; Bone Development - physiology; Case-Control Studies; Cross-Sectional Studies; Endocrinopathies; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Hormone Replacement Therapy - methods; Humans; Male; Medical sciences; Middle Aged; Organ Size; Sex Reassignment Procedures - methods; Time Factors; Transsexualism - diagnostic imaging; Transsexualism - metabolism; Transsexualism - physiopathology; Transsexualism - therapy; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology; Young Adult; Human; Obesity; Transsexualism; Nutrition; Hormone therapy; Nutrition disorder; Sex; Metabolic diseases; Male; Long term; Body composition; Osteoarticular system; Geometry; Bone mass; Female; Bone; Endocrinology; Nutritional status
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2012-1187

Context: Female-to-male transsexual persons (transsexual men) undergo extreme hormonal changes due to ovariectomy and testosterone substitution, allowing studies on sex steroid effects on bone geometry and physiology in the adult. Objective: The objective of the study was to examine the effects of cross-gender sex steroid exposure on volumetric bone parameters in transsexual men. Design: This was a cross-sectional study. Setting: Participants were recruited from the Center for Sexology and Gender Problems at the Ghent University Hospital (Ghent, Belgium). Participants: Fifty transsexual men after sex reassignment surgery with 50 age-matched control women and an additional 16 transsexual men before testosterone substitution and sex reassignment surgery with 16 control women participated in the study. Main Outcome Measures: The main outcome measures were areal and volumetric bone parameters using dual-energy X-ray absorptiometry and peripheral quantitative computed tomography, body composition (dual-energy X-ray absorptiometry), sex steroids, markers of bone turnover and grip strength. Results: Before hormonal treatment, transsexual men had similar body composition and bone geometry as female controls. The transsexual men on long-term testosterone therapy, however, demonstrated a higher lean body mass and muscle mass and a greater grip strength as well as a lower body and subcutaneous fat mass and a larger waist and smaller hip circumference compared with female controls (all P < 0.001). We observed a larger radial cortical bone size (P < 0.001) and lower cortical volumetric bone mineral density at the radius and tibia (P < 0.05) in transsexual men on testosterone therapy. Conclusions: Transsexual men on testosterone substitution therapy present with a different body composition with more muscle mass and strength and less fat mass as well as an altered bone geometry with larger bones compared with female controls.