The prevalence of osteoporosis in adults with cystic fibrosis

Cystic fibrosis (CF) patients have several risk factors for the development of osteoporosis. These include calcium and vitamin D malabsorption, malnutrition, reduced levels of activity, delayed puberty, hypogonadism, glucocorticoid use, cyclosporin use, and chronic infection. Recent improvements in the nutritional care of CF patients may significantly reduce the impact of some of these risk factors in the paediatric population. However, for the majority of CF adults these risk factors remain. The aim of this study is to determine the prevalence of osteoporosis in adults with CF. 80 CF subjects (40 male), mean (SD) age 26 (7.6) years, FEV1 % predicted 54.8 (21.5), BMI 20.8 (2.2) had their bone mass measured in the distal forearm using SXA (Osteometer DTX-100) and in the lumbar spine and hip using DXA (Hologic QDR 4500). Results were expressed as both Z and T scores. Bone mass was judged to be reduced if the Z score was ≤ -2, and osteoporosis present if the T score was ≤ -2.5 . Bone mass was reduced at all sites : Distal Ultra Distal Spine Total Hip Mean Z -0.76 -0.39 -1.28 -1.12 (SE) (0.11) (0.12) (0.13) (0.14) p vs zero <0.0001 0.002 <0.0001 <0.0001 % reduced 13.6 4.5 27.5 20.0 % osteoporotic 12.7 2.5 16.5 12.7 37.5 % of patients had reduced bone mass at either the wrist, spine or hip and 26.3 % had osteoporosis at one of those sites. Age, FEV1 % predicted, FVC % predicted and BMI failed to correlate with bone mass at any site. We conclude that osteoporosis is common in CF adults and that attention must be aimed at its management.