Which test is typically used to diagnose celiac disease?

The Anti-tissue transglutaminase antibody assay is the primary serological test used for diagnosing celiac disease. This test detects the presence of antibodies against tissue transglutaminase, an enzyme that plays a role in the pathogenesis of celiac disease. A positive result is indicative of an autoimmune response triggered by gluten ingestion, leading to intestinal damage in susceptible individuals.

This assay is preferred because it is highly sensitive and specific for celiac disease, making it an effective first-line screening tool. In cases where serological tests suggest celiac disease, an endoscopic biopsy may be performed to evaluate the degree of intestinal damage, but initially, the antibody test is the standard approach.

The gluten challenge test involves reintroducing gluten into the diet after a period of being gluten-free, which is generally not used as the first-line diagnostic method. An endoscopic biopsy, while definitive in diagnosing the disease by assessing mucosal damage, is more invasive and typically used if serological tests are positive. The fecal fat test is more helpful in diagnosing conditions like pancreatic insufficiency rather than celiac disease specifically.