Low Aromatase Activity and Estradiol/Sex Hormone Binding Globulin Ratio are Associated with Total Hip Bone Mineral Density and the Presence of Osteoporosis: A Study in Chinese Postmenopausal Women.

Several groups have reported the important role of estradiol (E2) and testosterone (T) in postmenopausal osteoporosis (PMOP). Because aromatase catalyzes the conversion of T to E2, the purpose of this study was to determine the influence of aromatase activity on the bone mineral density (BMD) in postmenopausal women. A total of 344 postmenopausal women were selected for this study. Serum E2, T, sex hormone-binding globulin (SHBG), calcium (Ca), alkaline phosphatase (ALP), C-terminal telopeptide of type I collagen (CTX), and procollagen type I amino-terminal propeptide (PINP) were examined. The E2/T was positively associated with total hip BMD and PINP (p<0.05). When E2/T was divided into quartiles, participants in lower quartiles of E2/T were likely to have higher PINP and lower BMD (p<0.05). The prevalence of osteoporosis significantly increased as E2/T ratio decreased. The receiver operating characteristic (ROC) curves were constructed for serum E2, free E2 index (FEI), and E2/T, to assess their diagnostic accuracy in PMOP. The overall area under the curve (AUC) were 0.83 (95% CI=0.77-0.88) for E2, 0.87 (95% CI=0.82-0.92) for FEI, and 0.89 (95% CI=0.85-0.94), respectively. In conclusion, the study suggests that in postmenopausal women, aromatase activity could be an important determinant of skeletal health. The women with lower aromatase activity may have greater likelihood of PMOP and the E2/T was expected to be a valuable indicator for the prediction of PMOP and to monitor the process of osteoporosis.