Sex steroids and bone health in older Chinese men

Summary: This study examines the association between sex steroids, bone mineral density (BMD), and incident fractures in 1,489 community-living Chinese men aged 65 and over. Chinese men with low serum estradiol levels display elevated bone loss and increased risk of fractures similar to findings in Caucasians. Introduction: This study examines the association between serum total testosterone (TT), free testosterone (free T), estradiol (E2), bioavailable estradiol (bioE2), sex hormone binding globulin (SHBG), BMD, and incident fractures. Methods: This is a cohort study with 4-year follow-up in the community in Hong Kong SAR, China. One thousand four hundred eighty-nine community-living Chinese men aged 65 and over participated. Sex steroid levels and BMD were measured at baseline; BMD was repeated after 4 years of follow-up, and fracture incidence from ascertainment from hospital databases was determined over 4 years of follow-up. Results: The strongest age-adjusted positive association with total hip and femoral neck BMD was with bioE2, followed by E2. Greater bone loss occurred in the lowest quartile of E2 and bioE2. The lowest quartile of free T and bioE2 and the two highest quartile of SHBG were associated with the highest percentage of participants with incident fractures. Those in the lowest quartile of E2 and bioE2 had approximately a 50% increased risk of incident fractures compared with the other three quartiles. This relationship remains significant for nonvertebral incident fractures (hip, radius, pelvis, and humerus) for E2 only, but not bioE2. Compared with the group with the three highest quartiles of TT and E2, the group with the lowest quartile of both had approximately twice the risk of nonvertebral osteoporosis-related incident fractures. Conclusion: Chinese men with low serum estradiol levels display elevated bone loss and increased risk of fractures similar to findings in Caucasians.