Vitamin D deficiency, bone mineral density and weight in patients with advanced pulmonary disease

Objective. To study the influence of underweight, body composition and vitamin D deficiency on bone mineral density in patients with advanced pulmonary disease. Design. Cross-sectional study with time span for inclusion set at 5 years. Setting. The clinical work and biochemical analyses were carried out at Rikshospitalet University Hospital, Norway. Analyses for vitamin D metabolites and bone markers were carried out at Aker University Hospital, and bone measurements at Clinic of Osteoporosis. Subjects. Seventy-one candidates for lung transplantation (63% chronic obstructive pulmonary disease, 42 underweight and 29 normal weight) were included. Main outcome measures. Body composition, bone mineral density at lumbar spine and femur neck, serum concentration of calcidiol and vitamin D intake. Results. Subnormal calcidiol levels were present in 52% of the underweight patients and 69% of the normal-weight patients. The resulting models of linear regression showed that for the lumbar spine T scores model, the total variation of 16.7% was explained by group (underweight/normal weight), sex and age. For the femur neck T scores model, the total variation of 20.4% was explained by the interaction of underweight and vitamin D deficiency (with borderline significance) and by arm muscle circumference percentage of standard. In patients with normal calcidiol levels, the median intake of vitamin D was 17 mug in the underweight patients and 11 mug in the normal-weight patients. Conclusions. Vitamin D deficiency was common in both underweight and normal-weight patients, but only in the underweight patients, an association between vitamin D deficiency and reduced femur neck T scores was indicated.