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

BACKGROUND: 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. METHODOLOGY: 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. RESULTS: 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. CONCLUSION: 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.