tTG-IgA and tTG-IgG tests
The tTG-IgA test is the preferred celiac disease serologic test for most patients. Research suggests that the tTG-IgA test has a sensitivity of 78% to 100% and a specificity of 90% to 100%.2 The performance of this test may depend on the degree of intestinal damage, making the test less sensitive in patients who have mild celiac disease. The test may also be less sensitive in children younger than age 2. The tTG-IgA test is most often an enzyme-linked immunosorbent assay (ELISA).
Health care professionals may order the tTG-IgG test to help diagnose celiac disease in patients who have IgA deficiency. The tTG-IgG test is not useful in other circumstances.
EMA-IgA test
Health care professionals may use the EMA-IgA test after the tTG-IgA test to help make a diagnosis of celiac disease more certain. Research suggests that the EMA-IgA test has a sensitivity of 86% to 100% and a specificity of 97% to 100%.2 The performance of this test may depend on the degree of intestinal damage, making the test less sensitive in patients who have mild celiac disease. The test may also be less sensitive in children younger than age 2.
The EMA-IgA test is an immunofluorescent assay that is more expensive and time-consuming to perform than the tTG-IgA test. The EMA-IgA test is also qualitative, making the results more subjective than tTG-IgA test results.
DGP-IgA and DGP-IgG tests
The DGP tests are less sensitive and specific than the tTG-IgA test.3 However, health care professionals may order DGP tests in certain circumstances. For example, because tTG and EMA tests may be less sensitive in infants and young children, some experts recommend combining the DGP tests with the tTG-IgA test in children younger than age 2. For patients with IgA deficiency, health care professionals may order the DGP-IgG test