Bone mineral and body composition alterations in paediatric cystic fibrosis patients

With the increased life span of cystic fibrosis (CF) patients, CF-related bone diseases could have an increased prevalence and morbidity in this group. In children, previous retrospective and prospective studies have yielded conflicting results on bone mineralization. To monitor body composition and bone mineral status of children with CF. We reviewed the dual-energy X-ray absorptiometry (DXA) data of 161 children with CF (age 10 +/- 4.8 years). Total body bone mineral content (BMCt), total lean tissue mass (LTMt) and total fat mass (FMt) were measured and compared to expected data calculated from ideal weight for height (Wi; e.g. BMCti, LTMti, FMti). The bt (BMCt/BMCti), lt (LTMt/LTMti) and ft (FMt/FMti) ratios were used as quantitative variables. Low bt ratio was found at all ages (mean bt ratio 0.94 +/- 0.10; P < 0.001), even in children < 6 years of age. However, the children's BMCt was satisfactorily adapted to their weight. lt and ft ratios were not constant across age groups. Children < 10 years had 8% reduction of their lt ratio, maintaining normal levels thereafter. The opposite trend was found for ft ratio. Poor clinical, nutritional status and vitamin A levels were correlated with bt and lt ratios. Our results indicate that children with CF could have early alterations in their bone status and that lt and ft ratios did not have constant values across ages. Interpreting DXA data using this approach is suitable in children with CF.