Eosinophil Protein X (EPX) is a water-soluble protein that is found in eosinophils.
EPX levels in stool are a marker of eosinophil activity in the gastrointestinal system. Fecal EPX abnormality is suggestive of food allergy, eosinophil-driven inflammation (caused by parasites). The test has been shown to have higher specificity and positive predictive value for detecting disease activity in inflammatory bowel disease compared to fecal calprotectin.
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