The tTG antibody test (antibody against tissue transglutaminase) is an important blood test for diagnosing celiac disease. This test detects the presence of IgA (and sometimes IgG) antibodies produced by the immune system in response to the enzyme tissue transglutaminase (tTG). In individuals with celiac disease, consuming gluten (a protein found in wheat, barley, and rye) triggers immune system activation and an attack on tTG in the small intestine. The tTG-IgA test serves as the primary test for screening and diagnosing celiac disease and possesses high sensitivity and specificity. Positive results are usually followed by a small intestine biopsy for final confirmation. This test is also used to monitor response to a gluten-free diet. It is essential to consider total IgA levels in the blood, as IgA deficiency may cause false-negative results. In suspected cases, supplementary tests such as EMA (anti-endomysial antibodies) or deamidated gliadin peptide (DGP) antibodies may also be performed.
