Endogenous Hormones, Muscle Strength, and Risk of Fall-Related Fractures in Older Women

Background. Among older people, fracture-causing fall often leads to health deterioration. The role of endogenous hormone status and muscle strength on fall-related fracture risk is unclear. This study investigates if, after adjustment for bone density, endogenous hormones and muscle strength would predict fall-related limb fracture incidence in older community-dwelling women followed-up over 10 years. Methods. As a part of a prospective population-based study, 187 75-year-old women were investigated. Serum estradiol, testosterone, sex hormone binding globulin, and dehydroepiandrosterone sulfate concentrations were analyzed, and isometric muscle strength and bone mineral density were assessed. Fall-related limb fractures were gathered from patient records. Results. Serum estradiol concentration was a significant predictor of fall-related limb fractures. Women with serum estradiol concentrations less than 0.022 nmol/L had a 3-fold risk (relative risk 3.05; 95% confidence interval, 1.26–7.36), and women with estradiol concentrations between 0.022 and 0.066 nmol/L doubled the risk (relative risk 2.24; 95% confidence interval, 0.97–5.19) of fall-related limb fracture compared to the women with estradiol concentrations above 0.066 nmol/L. Adjustment for muscle strength and bone mineral density did not materially change the risk estimates. High muscle strength was associated with a low incidence of fall-related limb fractures. Conclusions. This study showed that in 75-year-old women higher serum estradiol concentration and greater muscle strength were independently associated with a low incidence of fall-related limb fractures even after adjustment for bone density. Our results suggest that hormonal status and muscle strength have their own separate mechanisms protecting from fall-related fractures. This finding is of importance in developing preventive strategies, but calls for further study.