Reliable quantification of fecal elastase-1: A study on sample stability, IDK ELISA and IDK Extract® device

Quantitation of fecal elastase 1 (FE-1) is a non-invasive test for pancreatic function to detect moderate or severe exocrine insufficiency. The enzyme-linked immunosorbent assays (ELISA) are well-established tests for FE-1 detection. Traditional sample preparation by manual weighing and extraction is laborious, but new sample devices allow more effective sample preparation. FE-1 in stool has good stability but systematic studies on FE-1 stability in sampling and extraction devices are lacking. We examined the stability of FE-1 in the IDK Extract® device and intact stool samples at room temperature, 4 °C or -20 °C. Furthermore, we assessed the suitability of the IDK Extract® device for FE-1 testing and compared the performance of IDK FE-1 ELISA to that of the established ScheBo assay. FE-1 is stable in IDK Extract® device and intact stool for at least 29 days at all storage temperatures tested with deviation < 20 % from day zero concentration. When compared to weighing, the IDK Extract® device proved to be a reliable tool for sample preparation. Based on common clinical decision limits of pancreatic exocrine function, the ScheBo and IDK assays showed good agreement. In conclusion, IDK FE-1 assay together with the IDK Extract® device offers an effective and reliable method to determine exocrine pancreatic insufficiency. FE-1 is stable at various temperatures and the IDK and ScheBo assays perform equally. Thus, stool samples from outpatient clinics can be transported to the analytical laboratory cost-effectively at room temperature.