ABSTRACT. Observational studies suggest that low concentrations of serum 25-hydroxyvitamin D (25(OH)D) and high concentrations of parathyroid hormone (PTH) are associated with a higher risk of mortality. The aim of this study was to examine whether 25(OH)D and PTH concentrations are independently associated with overall and disease-specific (cardiovascular and cancer-related) mortality in a large, prospective population-based cohort of older adults. Data from 1317 men and women (65-85 years) of the Longitudinal Aging Study Amsterdam were used. Cox proportional hazard analyses were used to examine whether 25(OH)D and PTH at baseline were associated with overall mortality (with a follow-up of 18 years) and disease-specific mortality (with a follow-up of 13 years). Compared to persons in the reference category of ≥75nmol/L, persons with serum 25(OH)D <25nmol/L (HR 1.46; 95% CI: 1.12-1.91) and 25-49.9nmol/L (HR 1.24; 95% CI: 1.01-1.53) had a significantly higher risk of overall mortality, as well as men with baseline PTH concentrations ≥7pmol/L (HR 2.54 (95% CI: 1.58-4.08)), compared to the reference category of <2.33pmol/L. The relationship of 25(OH)D with overall mortality was partly mediated by PTH. Furthermore, men with PTH concentrations of ≥7pmol/L (HR 3.22; 95% CI: 1.40-7.42) had a higher risk of cardiovascular mortality, compared to the reference category. No significant associations of 25(OH)D or PTH with cancer-related mortality were observed. Both 25(OH)D and PTH should be considered as important health markers.
