Association Between Sex Steroid Levels and Bone Microarchitecture in Men: The STRAMBO Study

Context: Data on the association between bone microarchitecture assessed by high-resolution peripheral quantitative computed tomography (HR-pQCT) and sex steroids in men are scarce. Objective: Our aim was to determine the association between serum sex steroids and bone microarchitecture assessed by HR-pQCT in men. Design: This is a cross-sectional analysis in the Structure of the Aging Men's Bones cohort. Setting: The cohort was recruited from the general population. Participants: We examined 1169 male volunteers aged 20-87 years. No specific exclusion criteria were used. Interventions: We collected blood samples and performed HR-pQCT at the distal radius and distal tibia. Main Outcome Measures: We tested the hypothesis that low sex steroid levels are associated with poor bone microarchitecture in men. Results: Men aged younger than 65 years with bioavailable 17 beta-estradiol (bio-17 beta-E2) levels of 14.4 pmol/L or less had higher cross-sectional and trabecular areas vs men with bio-17 beta-E2 greater than 14.4 pmol/L. In men aged 65 years or older, the higher the apparent free T concentration (AFTC), the higher was the distal tibia cortical density (P < .05). Cortical density and thickness as well as total and trabecular density increased with higher bio-17 beta-E2 levels. Similar results were found after adjustment for limb length and body height. Men with low AFTC and low bio-17 beta-E2 levels had lower cortical density and thickness at both skeletal sites compared with the reference group. In men with AFTC less than 272 pmol/L, those with low bio-17 beta-E2 less than 25 pmol/L had lower cortical density and thickness at both skeletal sites vs men having higher bio-17 beta-E2 levels. Conclusion: In men aged 65 years and older, low bio-17 beta-E2 levels were associated with poor cortical bone status and, to smaller extent, lower trabecular density.