A simple blood test to test for coeliac disease. People with coeliac disease who eat gluten have higher than normal levels of certain antibodies in their blood. These antibodies are produced by the immune system because it views gluten (the proteins found in wheat, rye, and barley) as a threat. You must be on a gluten-containing diet for antibody (blood) testing to be accurate.

tTG-IgA Test

For most children and adults, the best way to test for celiac disease is with the Tissue Transglutaminase IgA antibody (tTG-IgA), plus an IgA antibody in order to ensure that the patient generates enough of this antibody to render the coeliac disease test accurate. All coeliac disease blood tests require that you be on a gluten-containing diet to be accurate. The tTG-IgA test will be positive in about 93% of patients with coeliac disease who are on a gluten-containing diet. This refers to the test’s sensitivity, which measures how correctly it identifies those with the disease. The same test will come back negative in about 96% of healthy people without celiac disease.

There is also a slight risk of a false positive test result, especially for people with associated autoimmune disorders like type 1 diabetes, autoimmune liver disease, Hashimoto’s thyroiditis, psoriatic or rheumatoid arthritis, and heart failure, who do not have celiac disease.

IgA Endomysial antibody (EMA): The EMA test has a specificity of almost 100%, making it the most specific test for coeliac disease, although it is not as sensitive as the tTG-IgA test. About 5-10% of people with coeliac disease do not have a positive EMA test. It is usually reserved for difficult to diagnose patients.

Total serum IgA: This test is used to check for IgA deficiency, a condition associated with coeliac disease that can cause a false negative tTG-IgA or EMA result.

While it is very rare, it is possible for someone with coeliac disease to have negative antibody test results. If your tests were negative, but you continue to experience symptoms, consult your doctor and undergo further medical evaluation.