Pulmonary function, body composition, and protein catabolism in adults with cystic fibrosis

Am J Respir Crit Care Med. 2002 Feb 15;165(4):495-500. doi: 10.1164/ajrccm.165.4.2104065.


Increased survival in cystic fibrosis (CF) is associated with bone thinning and fat-free mass (FFM) loss. We hypothesized that the severity of lung disease would be associated with increased protein catabolism and systemic inflammatory status in clinically stable patients. Forty adults with CF and 22 age-matched healthy subjects were studied. Body composition was determined by dual-energy X-ray absorptiometry. Urinary pseudouridine (PSU), a marker of protein breakdown, and cross-linked N-telopeptides of type I collagen (NTx), a marker of bone connective tissue breakdown, serum tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and their soluble receptors were measured. A 3-d food intake diary revealed 21 patients had a low energy intake. Excretion of PSU (p = 0.019) and NTx (p < 0.01) was increased in patients and was inversely related to FEV(1); PSU (r = - 0.53, p = 0.001) and NTx (r = - 0.43, p < 0.01). Increased excretion of PSU and NTx (p < 0.05 for both) was also related to a low FFM. All inflammatory mediators were greater in patients and were related to PSU and NTx. Clinically stable adults were catabolic with both cellular and connective tissue protein breakdown, which was related to lung disease severity, systemic inflammation, and body composition.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Analysis of Variance
  • Biomarkers
  • Body Composition*
  • Bone and Bones / metabolism
  • Case-Control Studies
  • Connective Tissue / metabolism
  • Cystic Fibrosis / physiopathology*
  • Cytokines / metabolism
  • Energy Intake
  • Female
  • Humans
  • Male
  • Proteins / metabolism*
  • Pseudouridine / metabolism
  • Regression Analysis
  • Respiratory Mechanics*


  • Biomarkers
  • Cytokines
  • Proteins
  • Pseudouridine