Tissue Transglutaminase (tTG) Antibody, IgA

Testing for tTG IgA antibodies is recommended as an initial screen to identify patients at risk for celiac disease, and in whom duodenal biopsy should be performed to confirm disease.

Some patients may have positive tTG IgA but negative EMA IgA and/or deamidated gliadin peptide (DGP) IgA results, which may be associated with false positivity or may indicate early disease. Close clinical correlation with continued testing may be indicated in patients with a family history of or who are at increased risk for celiac disease. A positive serology but normal biopsy may also indicate a gluten-free diet (GFD) prior to testing, latent disease, or early enteropathy. Re-challenge with a gluten diet may be recommended if GFD had been initiated prior to subsequent testing. In the case of latent or early disease, HLA DQ2 and DQ8 testing may be necessary to determine risk for disease.

For patients with a high degree of suspicion for celiac disease and who test negative for tTG, EMA and/or DGP IgA tests, selective IgA deficiency should be considered and testing for tTG, EMA and/or DGP IgG antibodies performed.

If serology is negative and suspicion for celiac disease is strong, intestinal biopsy may be warranted. Biopsy is particularly important for patients with diarrhea, steatorrhea, weight loss, failure to thrive, or with inherited genetic deficiencies such Down or Turner syndrome.