The Tissue Transglutaminase IgM Antibody test is a blood test used to diagnose celiac disease, an autoimmune disorder that affects the small intestine. In celiac disease, the body’s immune system attacks the small intestine when gluten, a protein found in wheat, barley, and rye, is consumed. The Tissue Transglutaminase IgM Antibody test detects the presence of IgM antibodies, which are produced by the immune system in response to tissue transglutaminase, an enzyme that is found in the small intestine and is targeted by the immune system in celiac disease. A positive result on this test indicates the presence of these antibodies and suggests the possibility of celiac disease. This test is often used in conjunction with other tests and diagnostic procedures to confirm a diagnosis of celiac disease.