Recently, a new ELISA kit for determination of elastase 1 in faeces has become commercially available. Studies in patients with chronic pancreatitis have indicated that it is a simple and sensitive test of exocrine pancreatic function. The aim of this study was to assess the clinical value of this new test in cystic fibrosis. A total of 72 children were studied: 27 who were healthy, 22 with cystic fibrosis and 23 with non-pancreatic disorders. Oral pancreatic extracts were not discontinued in the children with cystic fibrosis. A small sample of faeces was collected from each subject for elastase 1 concentration and chymotrypsin activity determination. In all of the healthy children and most of those with non-pancreatic disorders (20/23), elastase 1 concentrations were greater than 500 microg/g; in contrast, the vast majority (20/22) of children with cystic fibrosis had very low values (less than 20 microg/g). The differences between children with cystic fibrosis and the other two groups were highly significant (P < 0.001). With a cut-off level of 132 microg/g, the sensitivity and specificity of faecal elastase 1 for the determination of exocrine pancreatic insufficiency were 96% and 100%, respectively. The specificity of faecal chymotrypsin was 96%, but its sensitivity was not calculated since the children with cystic fibrosis continued to take pancreatic extracts during the study.
Conclusion: The determination of faecal elastase 1 concentration is a simple and reliable means of assessing exocrine pancreatic function in children with cystic fibrosis. Results are not influenced by non-pancreatic disorders or by enzyme supplementation.