[Vitamin D deficiency and hip fracture].

Vitamin D deficiency is common in the elderly, especially in patients with hip fracture. Elderly people infrequently stay outside in the sunshine, and nutrition is deficient in vitamin D. In addition, the hydroxylation of vitamin D into active metabolites decreases with age. Vitamin D deficiency ultimately leads to osteomalacia, but in an earlier stage it causes secondary hyperparathyroidism, which is accompanied by increased bone turnover and cortical bone loss. Along these pathways vitamin D deficiency may contribute to the pathogenesis of hip fractures. In a survey in Amsterdam vitamin D deficiency was observed in more than 60% of the patients with hip fracture. Transilial bone biopsy showed signs of high turnover and cortical bone loss in more than 20% of patients. The elderly which are institutionalized carry an increased risk. Prevention or vitamin D deficiency is possible by adequate exposure to ultraviolet light. Primarily, the elderly should be encouraged to go out into the sunshine regularly. Advice on nutrition may be given additionally. When sunshine exposure is negligible, as in many disabled and institutionalized elderly, a daily supplement of vitamin D3 400 IU should be given. Preventive measures have to be evaluated prospectively. Vitamin D deficiency is not the most important risk factors for hip fractures, but the easiest to correct.