[ association between vitamin D and bone mineral density in postmenopausal women]

ABSTRACT

There are inconsistent data regarding the role of vitamin-D in determining bone mineral density [BMD] especially in less severe vitamin-D deficiency. The aim of this study was to investigate the possible association between 25[OH]D and BMD in healthy free-living postmenopausal women in a population-based study. We enrolled 245 postmenopausal women, aged between 40 to 80 years, randomly selected from the Tehran Lipid and Glucose Study. Measurements of BMD were taken at the lumbar spine and upper femur by dual X-ray absorptiometry; additional to demographic and anthropometric data, serum 25[OH]D, PTH, calcium, phosphorus and alkaline phosphatase were measured according to the currently used laboratory methods. Bivariate and multivariate analyses were used to explore the association between 25[OH]D, BMD and other clinical and biochemical variables. Mean age and duration of menopause were 58 +/- 7 and 9.4 +/- 6.8 years, respectively; 25[OH]D [29.3 +/- 24.9 ng/ml] was <10 ng/ml and 11-20 ng/ml in 5.2% [n=13] and 37.6% [n=92] of women, respectively; 25[OH]D correlated inversely with LnPTH [r=-0.25, p<0.01]. However no association was found between 25[OH]D level and BMD at any of the skeletal scanning sites in bivariate analysis or multiple linear regression analyses, after adjusting for age, years since menopause, body mass index [BMI], calcium and LnPTH. In the multivariate analyses, BMD correlated inversely with LnPTH, in addition to age and BMI [R2=20%, p=0.03] only in femoral neck, but not at any other sites. This study showed no association between 25[OH]D and BMD in postmenopausal women