High serum 25-hydroxyvitamin D levels do not retard postmenopausal bone loss in Japanese women: the Yokogoshi study

We conducted a cohort study exploring an association between serum 25-hydroxyvitamin D (serum 25(OH)D) and parathyroid hormone (PTH) levels and 5-year changes in bone mineral density (BMD) in 482 postmenopausal women. High serum 25(OH)D levels do not retard postmenopausal bone loss within the lumbar spine or femoral neck, and high PTH levels potentially increase hip bone loss. Purpose The aim of this study was to explore an association between serum 25(OH)D levels and 5-year changes in BMD in postmenopausal women. Methods This 5-year cohort study included 482 women between 55 and 74 years of age who lived in a community in Japan. Medical examinations were conducted in 2005 and 2010. Data were obtained on baseline serum 25(OH)D and intact parathyroid hormone (iPTH) levels. Outcomes of this study were 5-year changes in BMDs of the lumbar spine and femoral neck. Covariates included years since menopause, body mass index (BMI), lifestyle factors, and weight change. Changes in BMDs among quartiles of serum 25(OH)D were compared with analysis of covariance. Results The mean age of subjects was 63.1 years, and mean serum25(OH)D levelswere 56.0 nmol/L. Age and decrease in weight were significantly associated with decreases in BMDs of both the lumbar spine (P for trend<0.001 and =0.002, respectively) and femoral neck (P for trend=0.026 and <0.001, respectively); low BMI was associated with a decrease in lumbar spine BMD (P for trend<0.001). No significant associations were found between serum 25(OH)D levels and changes in BMDs. High serum iPTH levels were associated with a greater decrease in femoral neck BMD (P for trend=0.026). Conclusions High serum 25(OH)D levels do not retard postmenopausal bone loss within the lumbar spine or femoral neck, and high PTH levels potentially increase hip bone loss.