The Effects of Serum Testosterone, Estradiol, and Sex Hormone Binding Globulin Levels on Fracture Risk in Older Men

Context: The relationship between sex steroids and fracture is poorly understood. Objective: The objective of the study was to examine associations between nonvertebral fracture risk and bioavailable estradiol (bioE2), bioavailable testosterone (bioT), and SHBG. Design: This was a case-cohort study. Setting: The Osteoporotic Fractures in Men Study (MrOS) was conducted in a prospective U.S. cohort in 5995 community-dwelling men 65 yr old or older. Participants: Participants included a subcohort of 1436 randomly chosen white men plus all 446 minorities and all those with incident hip and other nonvertebral fractures. Main Outcome Measures: Baseline testosterone and estradiol were measured by mass spectrometry (MS) and SHBG by RIA. Results: Men with the lowest bioE2 (59.1 nm) had greater risk of all nonvertebral fractures [adjusted hazard ratio (HR) [95% confidence interval]: 1.5 (1.2–1.9) and 1.4 (1.1–21.8), respectively]. Men with the lowest bioT (