Alison Jones, Consultant Clinical Biochemist, York and Scarborough NHS Foundation Trust
It is well documented that liquid/watery stool samples should not be tested for faecal elastase due to the risk of a false low result suggesting pancreatic insufficiency (a false positive). This is not a failure of the assay – it works in exactly the same way whether the sample is formed or liquid. The challenge is more in the interpretation of the result. Is the low result due to a poorly pancreas, or is it the body’s reaction to some other pathology causing dilution of the elastase in an individual with an otherwise functioning pancreas?