Fecal elastase-1 cut-off levels in the assessment of exocrine pancreatic function in cystic fibrosis

Background: Fecal elastase-1 (E1) test is a sensitive and specific indirect test. However, there are few data on the best cut-off level in the assessment of exocrine pancreatic function in cystic fibrosis (CF). Material and methods: In 725 CF patients and 243 healthy subjects (HS) from Greece, Russia, Poland and the United Kingdom, E1 concentrations were measured. The best cut-off levels for the discrimination between CF and HS (for whole group as well as for individual countries) were calculated. Results: The best cut-off level for the differentiation between CF pancreatic insufficiency and normal pancreatic function in HS was found to be 184 μg/g of feces. However, some inter-country differences were stated. E1 concentrations in the UK subgroup were significantly lower than those found in Polish and Russian CF patients. E1 concentrations in Greek patients were significantly higher than in the other countries. However, E1 concentrations in ΔF508 homozygotes were very similar in all studied subgroups. In conclusion: In clinical practice, instead of a single best cut-off level for the E1 test, we suggest using a range of values (160–200 μg/g). The presence of different best cut-off levels within countries is a practical consequence of the different distribution of pancreatic function.