Relation of serum 25 hydroxyvitamin D levels to bone mineral density in southern Chinese postmenopausal women: A preliminary study.

BACKGROUND & OBJECTIVES: Vitamin D insufficiency is prevalent in postmenopausal women and has been related to low bone mineral density (BMD). However, controversial results have been reported for the relationship between serum 25-hydroxyvitamin D [25(OH)D] levels and BMD. This study was done to investigate whether serum 25(OH)D levels were associated with BMD in postmenopausal women living in Guangzhou in southern China.

METHODS

This cross-sectional study involved 119 asymptomatic postmenopausal women, aged 48-85 yr, who were consecutively selected from Guangzhou city. BMD was measured at the lumbar spine and femoral neck. The correlation between serum 25(OH)D levels and BMD wes investigated.

RESULTS

With increasing serum 25(OH)D levels categorized as <20, 20-30, and ≥ 30ng/ml, the PTH levels decreased gradually ( P=0.031). Bivariate correlation analyses showed an inverse relationship between serum 25(OH)D and PTH levels after controlling for age and BMI (r=-0.209, P=0.023). Although subjects with vitamin D<30 ng/ml had significantly lower BMD, age- and BMI-adjusted serum 25(OH)D was weakly correlated with BMD at femoral neck (r=0.185, P0.045), and not at lumbar spine (r=0.172, p =0 0.063). In multiple regression analyses, serum 25(OH)D was a predictor for BMD at femoral neck (R 2= 0.424). However, serum β-CTX was a determinant for BMD at lumbar spine (R 2= 0.361).

INTERPRETATION & CONCLUSIONS: Serum 25(OH)D levels showed a positive correlation with BMD at femoral neck and serum β-CTX levels were inversely correlated with BMD at lumbar spine in postmenopausal women. Further studies are needed to elucidate the clinical impact of these findings.