Introduction: Adults with cystic fibrosis (CF) are known to have reduced bone mineral density and increase risk of fracture. The possible causes of reduced bone density in CF patients include poor nutrition, reduced calcium absorption, chronic lung infection, treatment with steroids and reduced ability to undertake load bearing exercise.

Methods: We used the Hologic QDR 4500 Dual X-ray Absorptiometry(DXA) to measure the lumbar spine bone mineral density (LSBMD) at L1-L4 in 26, 5-16 year old children with CF. LSBMD results were transformed into Z-scores(Standard Deviation Scores) for age using the normative LSBMD data provided by Hologic Inc. (based on healthy North American & French children). The disease severity was determined using the Shwachman-Kulczcki score. The lean body mass was also measured by the DXA.

Results: The mean LSBMD Z-score was -0.88 (p<0.001). Eleven children (42%) had LSBMD Z-score more than 1 standard deviation below the mean. Age, body weight, lean body mass and Tanner stage of pubertal development significantly correlated with LSBMD (all p<0.001).

Conclusions: Results of this cross-sectional study indicate that low LSBMD values are common among children with CF, even in those as young as 5-7 years. Interventions to improve bone density in children with CF are required in order to reduce the risk of fracture in late adolescence and adult life.Funding support from the Cystic Fibrosis Trust of United Kingdom