Bone mineral density and serum osteoprotegerin levels in pre- and postmenopausal women

Abstract

Introduction: Osteoprotegerin (OPG) is an essential regulator of bone turnover through its suppression on osteoclastogenesis. Findings from previous studies of serum OPG and bone mineral density (BMD) in humans have been conflicting. The objective of this study was to identity factors associated with serum OPG levels and to determine its effect on BMD in pre- and post- menopausal women. Methods: This is a part of the Hong Kong Osteoporosis Study. 2,343 community-dwelling, treatment and hormonal therapy naive female subjects aged 18 or above were recruited (679 premenopausal women, mean age 36.7±8.8 years; 1,664 postmenopausal women, mean age 62.6±8.5 years). Baseline demographic characteristics, serum biochemistry, hormonal profile and fasting serum OPG levels were obtained. Baseline BMD at the spine and hip were measured. Results: Serum OPG levels was correlated with age in both pre- and post-menopausal women (premenopause r=0.208, postmenopause r=0.258, both p<0.0001). After adjusting for age, OPG levels were positively correlated with serum estradiol (r=0.100, p<0.05) and negatively with follicular stimulating hormone (FSH, r=-0.114, p<0.01) in premenopausal but not postmenopausal women. In premenopausal women, higher serum OPG levels were associated with higher age- and BMI-adjusted BMD (spine r=0.147, p<0.05; femoral neck r=0.138, p<0.05; total hip r=0.148, p<0.05). In postmenopausal women, age-adjusted OPG showed no correlation with BMD in the linear regression model. However, a negative correlation was observed between OPG in quartiles and hip BMD (p-tread <0.01), but not spine BMD. Conclusions: Serum OPG level is an independent factor associated with higher BMD in pre-menopausal women. However it’s protective effect on BMD is not significant in post-menopausal women with low bone mass.