Bone density in children and adolescents with cystic fibrosis

Objective: To assess bone mineralization in children and adolescents with cystic fibrosis. Design: A cross-sectional, observational study of bone mineral density (BMD) in the lumbar vertebrae and the proximal femur of 62 patients aged 4.9 to 17.8 years (mean, 10.7 years). The age-normalized BMD findings (z scores) were correlated with multiple variables, including measures of pulmonary disease, nutritional status and growth, genotype, calcium intake, and serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels. Results: The mean BMD z score was -1.03 +/- 0.14 (+/-SE) in the lumbar vertebrae and -0.71 +/- 0.17 in the proximal femur, The BMD in this age range declined relative to normal values at a rapid rate of roughly 1 SD every 6 to 8 years. The BMD z scores correlated well with multiple measures of disease severity, particularly weight and forced expiratory volume in 1 second. Conclusions: Significant osteoporosis in adults with CF results at least in part from a failure to accumulate bone mineral at a normal rate during skeletal growth and development, The cause of this is likely multifactorial. With increasing longevity, the skeletal consequences of CF become an important consideration.