Nutritional management of cystic fibrosis patients

We critique recent advances in nutritional care of patients with cystic fibrosis focusing on our understanding of the role of fecal elastase as a pancreatic function test, enzyme replacement therapy and bone health.

Fecal elastase measured by the monoclonal antibody method is a useful screening test for delineating cystic fibrosis patients with pancreatic insufficiency (needing enzyme replacement therapy) from those with pancreatic sufficiency. Cutoff levels, however, have not been clearly defined, particularly in infancy. Newer enzyme products that attempt to improve the intralumenal intestinal pH with bicarbonate or using a combination of unprotected and enteric coated products fail to completely correct nutrient maldigestion. Compromised bone health in cystic fibrosis patients may be due to multiple factors including calcium, vitamin D, and vitamin K deficiencies and lung inflammation. Current recommendations for treatment of bone health in cystic fibrosis are not evidence-based.

Fecal elastase is a useful marker of pancreatic function but limitations for this test exist. The presence of an acidic intestinal milieu and hitherto poorly defined intestinal factors may contribute to the failure of current enzyme preparations to correct nutrient assimilation in cystic fibrosis. The many factors that contribute to bone health must be evaluated when developing treatment strategies.