Utility of Fecal Elastase-1 in Estimating Exocrine Pancreatic Function in Cystic Fibrosis: A Scoping Review

In people with cystic fibrosis (pwCF), identification of exocrine pancreatic insufficiency (EPI) is essential to prevent steatorrhea and, if not managed actively, can lead to catastrophic consequences. Fecal elastase-1 (FE-1) is a widely used test to screen for EPI in cystic fibrosis (CF). Once thought permanent, some patients with EPI on CF transmembrane conductance regulator (CFTR)-directed therapies (modulators) have been noted to show improvement in EPI. Here, we evaluated the utility of FE-1 in pwCF.

We performed a scoping review and searched several databases for the terms/concepts of "cystic fibrosis" and "fecal elastase-1" and their synonyms. The search period was from 1-1-2003 to 7-31-2025. We included all age groups and used a web-based platform for compiling and sorting out the articles.

We combined the eligible studies to synthesize information on four questions: Utilization of FE-1 in CF (when to screen for EPI, how often to screen); Comparison of diagnostic accuracy of FE-1 versus other tests; Definition of ideal cut-off for FE-1 in evaluating EPI in CF; Utilization of FE-1 in pwCF managed on CFTR-directed therapies.

All pwCF should have EPI evaluated at diagnosis. Among various tests, FE-1 is the most commonly utilized test for screening EPI. A value of < 200 μg/g of stool is consistent with EPI and is highly sensitive for EPI diagnosis. A value of < 100 μg/g is highly specific for severe EPI. Repeating FE-1 should be considered in the current era of modulators, especially with a change in clinical status.