Osteoanabolic Estrogen Therapy in a Transsexual Man

A 31-year-old transsexual male undergoing male-to-female transition experienced significant changes in bone mass during hormone therapy. Initially treated with cyproterone acetate (100 mg/day) for 30 months, his bone mass decreased by 5% per year, leading to high turnover osteoporosis. However, after adding oral oestradiol valerate (2 mg/day), his bone mass increased by 4% per year. This study highlighted the crucial role of sex hormones, including oestrogens, in maintaining bone mass in males, demonstrating their anabolic effects on bone.