Serum 25(OH)D3 vitamin status of elderly Finnish women is suboptimal even after summer sunshine but is not associated with bone density or turnover

摘要

Objective Concentrations of 50 and 75 nmol/l are proposed as serum 25-hydroxyvitamin D (25(OH)D) target for older people from the view of bone health. We evaluated vitamin D status of elderly Finnish women in light of these definitions, its relationship to bone mineral density (BMD) and turnover, and improvement by summer sunshine. Design Population-based study. Methods A total of 1604 ambulatory women aged 62–79 years were studied; 66% used vitamin D supplements. Serum 25(OH)D3 was measured with HPLC before and after summer, and heel BMD in spring. In subgroups, serum parathyroid hormone (PTH) and type I procollagen aminoterminal propeptide (PINP) were analyzed. Results In spring, 60.3% of the women had 25(OH)D3 ≤50 nmol/l, and the target of 75 nmol/l was reached by 9.1%. For supplement users, the respective numbers were 52.1 and 11.9%. Serum 25(OH)D3 did not determine BMD or bone turnover measured by serum PINP. Summer sunshine increased serum 25(OH)D3 by 17.4% (P0.0001), but in autumn 84% of the subjects remained under the target of 75 nmol/l. In supplement users, PTH remained stable but decreased in others during summer (P=0.025). Conclusions Vitamin D status of elderly Finnish women is suboptimal if 25(OH)D3 levels of 50 or 75 nmol/l are used as a threshold. It is moderately increased by supplement intake and summer sunshine. However, 25(OH)D3 concentrations did not influence bone density in terms of serum PINP and bone turnover rate.