- Anti-tissue Transglutaminase (anti-tTG) Antibodies, IgA: This is the most sensitive and specific blood test for celiac disease and is typically the initial test performed.
- Anti-tTG, IgG: The test for the IgG class of anti-tTG is less sensitive and specific than the IgA class but is not affected by IgA deficiency, which is more common in those with celiac disease.
- Deamidated Gliadin Peptide (DGP) Antibodies, IgA: a relatively new test that may be positive in some people with celiac disease who are anti-tTG negative; DGP IgG testing along with anti- tTG IgG is recommended by the American College of Gastroenterology (ACG) for those who have low IgA or IgA deficiency.
- Anti-Gliadin Antibodies (AGA), IgG and IgA: an autoantibody against the gliadin portion of gluten; guidelines by the ACG published in 2013 do not recommend this test for the primary detection of celiac disease due to concerns with its accuracy.
- Anti-Endomysial Antibodies (EMA), IgA: less common, provides essentially the same information as anti-tTG.
- Anti-Reticulin Antibodies (ARA), IgA: less common; not as specific or sensitive as other tests.
- Anti-Actin IgA (F-actin): less common; may indicate increased intestinal damage.
To confirm a diagnosis of celiac disease, a biopsy of the small intestine is examined to detect damage to the intestinal villi.
Genetic tests that look for the markers that are strongly associated with celiac disease are available but not routinely ordered. These tests include the Human Leukocyte Antigen (HLA) markers DQ2 and DQ8. A positive result does not diagnose celiac disease since about 30% of the general population also carry these markers but do not have the disease. A negative result, however, can essentially rule out celiac disease in those individuals for whom results of other tests, including biopsy, are unclear. These tests are most useful for family members of individuals with the disease who fall into a high risk category and for those with other diagnostic test results that are inconclusive.
- CBC (complete blood count) to look for anemia
- ESR (erythrocyte sedimentation rate) to detect inflammation
- CRP (C-Reactive protein), a more sensitive measure of inflammation
- CMP (complete metabolic panel) to determine electrolyte, protein, and calcium levels and to verify the status of the kidney and liver
- Vitamin D, B12 and folate to detect vitamin deficiencies
- Iron, iron binding capacity or transferrin, and ferritin to detect iron deficiency
- Stool fat, to help evaluate malabsorption
X-rays of the intestines after barium ingestion may show characteristic findings that indicate intestinal damage.