Determinants of sex hormone-binding globulin in normal postmenopausal women

OBJECTIVE To examine the factors influencing the levels of sex hormone-bind ing globulin (SHBG) in normal postmenopausal women by assessing the relatio nship between SHBG and measured anthropometric, metabolic and hormonal vari ables. DESIGN Cross-sectional, observational study. SUBJECTS and METHODS Seventy normal postmenopausal women aged 47-71 years ( mean 58 years), participated in the study. Information was collected on med ical, reproductive and smoking history, alcohol use, dietary intake and phy sical activity. Body composition measurements using dual-energy absorptiome try, and analyses of biochemical and hormonal indices were performed. RESULTS Bivariate correlation coefficients indicated that SHBG was inversel y related to body weight (r = - 0.44), fat mass (r = - 0.35), and abdominal obesity (r = - 0.42). It was also inversely related to the glucose and ins ulin levels during an oral glucose tolerance test (- 0.24 < r < - 0.40), se rum oestradiol (r = - 0.26), and physical activity (r = - 0.24). Multiple r egression analysis indicated that significant independent correlates of SHB G concentration were fat mass, physical activity, alcohol intake, serum oes tradiol, and insulin-like growth factor-1, all having a negative impact on SHBG. CONCLUSIONS From these observed associations, it is concluded that maintena nce of body weight, moderate alcohol consumption, and physical activity wil l tend to reduce SHBG concentrations in postmenopausal women, thereby incre asing the levels of free oestradiol. This mechanism could mediate the benef icial effects of these factors in preventing the development of osteoporosi s and cardiovascular disease.