Résumé
An increased rate of bone turnover increases risk of osteoporotic fracture later in life. The concentration of 25-hydroxyvitamin D that contributes to an elevated rate of bone turnover in older adults is unclear. The objective of this study was to investigate the associations between 25-hydroxyvitamin D and biochemical markers of bone turnover in an older, pan-European cohort. 25-hydroxyvitamin D and serum markers of bone-formation (osteocalcin and bone-specific alkaline phosphatase) were assessed by ELISA, while urinary markers of bone-resorption (pyridinoline and deoxypyridinoline) were assessed by HPLC. Six percent, 36%, and 64% of subjects had 25-hydroxyvitamin D concentrations <25, <50, and <80 nmol/L throughout the year, respectively. 25-hydroxyvitamin D was significantly and inversely correlated with serum bone-specific alkaline phosphatase (r = 0.119; p = 0.022) and urinary pyridinoline (r = 0.207; p < 0.0001) and deoxypyridinoline (r = 0.230; p < 0.0001). Stratification on the basis of tertiles [T] of 25-hydroxyvitamin D (< 47.6 [T-1]; 47.6-85.8 [T-2]; >85.8 [T-3] nmol/L), showed that urinary pyridinoline and deoxypyridinoline were significantly lower in subjects in the 2nd and 3rd compared to the 1st tertile (p < 0.015). Low vitamin D status (<50 nmol/L) was associated with an increased rate of bone turnover in this older pan-European cohort.