Development and validation of an improved test for the measurement of human faecal elastase-1

Background: Human faecal elastase-1 (FE-1) is an established biochemical test for the investigation of pancreatic exocrine insufficiency. Conventional extraction methods for FE-1 analysis can give false-positive results with watery stools. This is a major limitation as patients investigated for pancreatic disease commonly produce such stools. We have developed an improved FE-1 test that overcomes water interference by measuring the enzyme in dried faeces. Methods: A novel collection device for FE-1 analysis that involves drying and weighing the stool sample was developed in our laboratory and compared with a conventional wet method, E1 Quick-Prep (Schebo, Biotech AG, Germany). The concentration of faecal FE-1 was determined using a commercially available enzyme-linked immunosorbent assay method (Schebo). Results: FE-1 values obtained using the new dry extraction procedure (mean 1777 mu g/g dry stool) were higher when compared with the conventional wet analysis (mean 402 mu g/g stool). A 1:2 dilution in water, mimicking a loose stool, was found to affect FE-1 results obtained using the conventional wet extraction procedure. The new dry extraction method gave consistent results when water content was varied in the original stool sample. Conclusion: We have demonstrated that our new device overcomes water interference, allowing results to be obtained from stool samples that would otherwise be unsuitable for FE-1 analysis.