Bone loss in adults with cystic fibrosis: Prevalence, associated factors, and usefulness of biological markers

Abstract

Background Osteoporosis is a common complication of cystic fibrosis. Objective To determine the prevalence of osteopenia and osteoporosis in adults with cystic fibrosis and to look for factors associated with low bone mineral density (BMD) values. Methods During this prospective 2-year study, we collected clinical data (history, body mass index, and treatments) and laboratory data (nutritional and hormonal status, markers for inflammation and bone turnover, and calcium and phosphate levels). Lung function tests and a 6-meter walking test were performed. BMD was measured at the spine, total hip, and femoral neck. Results We included 55 patients (31 women) with a mean age of 31.9 years; 14 were homozygous and 25 heterozygous for the deltaF508 mutation and 20 (36%) had a history of fractures. BMD values indicated osteopenia in 32 (58.2%) patients and osteoporosis in 11 (20%) patients at one or more measurement sites. At all three sites, BMD values correlated with the body mass index, forced vital capacity as % predicted, and forced expiratory volume in 1 s as % predicted; at the femoral neck and total hip, BMD values correlated with the 6-meter walking test result and grip strength. Conclusion BMD was low in 78.2% of adults with cystic fibrosis. Three factors reflecting lung disease severity were associated with low BMD values, namely, respiratory function, physical function (walking test and grip strength), and nutritional status.