Hypovitaminosis D and response to supplementation in older patients with cystic fibrosis.

This study reports serum 25-hydroxy vitamin D (25-(OH)D) levels, bone mineral content and bone maturation in 20 adolescent and adult patients with cystic fibrosis, and their response to the internationally recommended dose of supplementary vitamin D (800 iu/day; 20 micrograms/day). Serum 25-(OH)D values were below normal in 75 per cent of patients and serum alkaline phosphatase values, corrected for age, were increased in 60 per cent. Bone mineral content, measured by photon beam absorptiometry, was below the normal range in 45 per cent of patients and bone age retarded in 45 per cent. Following supplementation with vitamin D 40 per cent of patients failed to achieve normal serum 25-(OH)D levels. We concluded that hypovitaminosis D occurs frequently in older patients with cystic fibrosis and is accompanied by osteopenia and retarded bone maturation.