Weight loss and severe cystic fibrosis

Adults with cystic fibrosis who experience weight loss that does not involve fat tissue or loss of fat-free mass, have more severe overall disease. Investigators have found that the loss of fat-free mass that is not obvious correlates with increased loss of bone mineral density and systemic inflammatory activity.Researchers from the University of Wales College of Medicine Academic Centre, UK, hypothesized that some adult patients of cystic fibrosis with a normal body mass index (BMI) may have 'hidden' fat-free mass loss and bone mineral density depletion that is related to more severe disease. To investigate, they measured bone mineral density and fat mass in 56 adults with cystic fibrosis and in 20 age-matched healthy control subjects. The researchers recorded lung function, physical activity, blood C-reactive protein (a marker of inflammation), and the number of exacerbations in the previous year. It was found that total fat-free mass was lower in patients than in healthy controls. No difference in fat mass, however, was observed between the groups. Among the 56 cystic fibrosis patients, 30 had a normal BMI. Of these 30 subjects, 12 had a hidden loss of fat-free mass. In addition, this group had lower scores on lung function tests, more frequent exacerbations, and higher circulating C-reactive protein.

The investigators concluded that it is clinically relevant to determine body composition in adults with cystic fibrosis and to identify all patients with loss of fat-free mass as an indicator of disease severity.