The Fecal Gluten Peptide assay is a direct measurement of the 33-mer gliadin peptide in stool. It is not an antibody or immune response test (as is fecal SIgA). If the gluten peptide is present in stool, then gluten has entered the digestive tract via consumption.
As a direct peptide measurement, it is not subject to the same limitations of immunosuppression as with antibody testing.
The Fecal Gluten Peptide marker helps eliminate the ambiguity of cross reactivity. If the Fecal Gluten Peptide is detected in stool, the patient has been directly exposure to gluten, specifically.
The detection of gluten peptide in stool indicates recent intake of gluten (within two to four days). When gluten is detected in the stool of a patient on a GF diet, the Fecal Gluten Peptide marker can guide the patient and healthcare provider to the source of "hidden" gluten exposures and increase adherence to a true therapeutic diet.