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

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.

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).

FE-1 values obtained using the new dry extraction procedure (mean 1777 microg/g dry stool) were higher when compared with the conventional wet analysis (mean 402 microg/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.

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.