Deamidated Gliadin Peptide (DGP) Antibodies, IgA and IgG

In individuals who produce sufficient total IgA, the most sensitive and specific serologic test for celiac disease (CD) diagnosis is tissue transglutaminase (tTG) IgA. Deamidated gliadin peptide (DGP) IgA should not be used for initial screening due to its low specificity and limited role in identifying undetected CD. In individuals who are IgA deficient, tTG IgG and DGP IgG antibody testing is recommended.

Reflexive panel testing is preferred to screen for CD.

Some patients may have positive tTG IgA results but negative endomysial antibody (EMA) IgA and/or DGP IgA results, which may indicate early disease or be associated with false positivity.

All serologic tests used to diagnose CD should be performed while the patient is on a gluten-containing diet. Upon initiation of a gluten-free diet, antibody titers decline in treatment-responsive patients and the time frame to normalize titers varies by case. If serology is negative and suspicion for CD remains strong, intestinal biopsy may still be warranted to establish a diagnosis.