Deamidated Gliadin Peptide (DGP) IgG & IgA Test

Gliadin is one of the proteins found in gluten, which is present in wheat, barley, and rye. In some people, the immune system reacts to a modified, or deamidated, form of this peptide by producing antibodies. This test looks at two antibody classes at once — IgG and IgA — which can give a clinician a broader view than either class alone. Antibody markers like these are part of how clinicians approach celiac disease, an immune condition in which eating gluten leads to a reaction affecting the small intestine. Measured together, the two classes are one tool among several in a full evaluation.

One important point sets antibody testing for celiac disease apart: it is generally done while a person is still eating gluten regularly. If gluten has already been removed from the diet, the immune markers can settle down and the picture becomes harder to interpret. Because of this, people talk with their clinician before making any dietary changes, so the timing of the test is planned rather than accidental. The sample itself is collected with a simple blood draw at a Quest patient service center.

People often look into DGP IgG and IgA when they or their clinician are exploring symptoms that can be associated with celiac disease, such as digestive discomfort, fatigue, or other concerns, or when celiac disease runs in the family. Measuring both antibody classes can be helpful because they can behave differently from person to person, and looking at the pair reduces the chance of leaning on a single signal. The IgG class is also useful when someone has a shortage of IgA. Because celiac evaluation is nuanced, these markers are chosen and interpreted with a clinician rather than used as a standalone answer.

The test measures IgG- and IgA-class antibodies directed at the deamidated gliadin peptide. Their presence reflects a particular kind of immune response related to gluten; it does not, by itself, establish a diagnosis. A clinician uses the pair as inputs, frequently alongside other antibody markers and, where appropriate, additional steps such as referral for further evaluation.

It helps to remember what antibody markers can and cannot do. They describe immune signals, not the full story of what is happening in the gut. That is exactly why celiac evaluation is guided by a clinician who can weigh several markers, symptoms, and history together rather than reading any one result in isolation.

The two antibody classes can carry different information, and a person may show a response in one but not the other. Looking at both together gives a clinician a wider view and helps account for situations where one class is less informative — for example, when someone has an IgA shortage that can affect IgA-based markers. The combined result still needs a clinician's interpretation, but the broader view is part of why the pair is often ordered together.

Celiac antibody markers generally reflect an ongoing immune response to gluten. When gluten is being eaten regularly, that response is more likely to be visible; when it has been removed, the markers can quiet down and the result becomes harder to interpret. For this reason people do not start a gluten-free diet on their own ahead of testing. Instead, they discuss timing with their clinician so the evaluation is planned and the results are meaningful. The sample is collected with a quick blood draw at a Quest patient service center.

Results will be emailed securely to you as a PDF.