Endogenous sex hormones, sex hormone-binding globulin, and muscle health: insights into sarcopenia and sarcopenic obesity from the Women's Health Initiative.

OBJECTIVE

The relationship between sex hormones and lean body mass in postmenopausal women is unclear. To address this, we conducted a longitudinal observational study using data from the Women's Health Initiative study.

METHODS

We analyzed endogenous serum sex hormones and sex hormone-binding globulin (SHBG) at baseline in 1,565 postmenopausal women not using hormone therapy, who underwent 3 lean body mass measurements over 6 years. Sex hormone concentrations were assessed at baseline using radioimmunoassay. Lean body mass was assessed by dual-energy x-ray absorptiometry at baseline, year 3 and 6. Free estradiol and free testosterone concentrations were calculated. Each sex hormone was analyzed independently of the other hormones. Associations between sex hormones or SHBG were examined using repeated-measures linear regression for lean mass and repeated-measures logistic regression for sarcopenia/sarcopenic obesity. Regression models were adjusted for age, race/ethnicity, lifestyle, and metabolic confounders.

RESULTS

Concentration of free testosterone in the highest quartile was associated with a 55% lower odds for sarcopenia compared with the lowest quartile (OR: 0.45; 95% CI: 0.25-0.81). Similarly, individuals with the highest concentration of free estradiol had a 54% reduced odds of sarcopenia (OR: 0.46, 95% CI: 0.28-0.76). Conversely, a higher concentration of SHBG at baseline was significantly associated with reduced total lean mass and a higher odds of sarcopenia.

CONCLUSION

Among postmenopausal women, higher SHBG concentrations at baseline were associated with lower lean body mass and a higher odds of sarcopenia, while higher free estradiol and free testosterone concentrations were associated with a lower odds of sarcopenia.