Gliadin (AGA) IgG is an antibody produced when the immune system reacts to gliadin, a protein found in gluten-containing grains such as wheat, barley, and rye. This marker was historically used in the evaluation of celiac disease but has largely been replaced by more specific tests such as deamidated gliadin peptide (DGP) and tissue transglutaminase (tTG) antibodies.
Despite its lower specificity, AGA IgG can still provide valuable insight into immune reactivity to gluten, particularly in individuals with selective IgA deficiency, where IgA-based tests may be unreliable. It is also sometimes elevated in individuals with non-celiac gluten sensitivity (NCGS), where symptoms occur without the intestinal damage seen in celiac disease.
What Does an Elevated AGA IgG Mean?
Elevated AGA IgG levels may suggest:
- Immune sensitivity to gluten
- Non-celiac gluten sensitivity
- Possible celiac disease (less specific)
- Increased intestinal permeability (“leaky gut”)
- Ongoing exposure to gluten in sensitive individuals
Because AGA IgG targets native gliadin (rather than deamidated gliadin), it is more prone to false positives and should not be used alone to diagnose celiac disease.
Symptoms Associated with Elevated Levels
Elevated AGA IgG may be associated with:
- Digestive symptoms (bloating, diarrhea, constipation)
- Fatigue or low energy
- Brain fog or difficulty concentrating
- Headaches or migraines
- Joint discomfort
- Skin issues
Some individuals may experience subtle or no symptoms, despite measurable immune activation.
Important Testing Considerations
Testing should be performed while consuming a gluten-containing diet to ensure accurate results.
AGA IgG is typically interpreted alongside:
- Tissue Transglutaminase (tTG) IgA and/or IgG
- Deamidated Gliadin Peptide (DGP) antibodies
- Total IgA levels
This combined approach improves diagnostic accuracy and helps distinguish between celiac disease and other forms of gluten sensitivity.
What to Do If Your Levels Are High
If AGA IgG is elevated:
- Follow up with more specific celiac testing (tTG and DGP antibodies)
- Continue consuming gluten until testing is complete
- Consult with a healthcare provider to determine the cause of immune activation
If a gluten-related disorder is confirmed, dietary changes—such as reducing or eliminating gluten—may be recommended based on your diagnosis.
Why This Marker Matters
AGA IgG can help identify immune responses to gluten that may not be captured by IgA-based tests, particularly in IgA deficiency or non-celiac gluten sensitivity. While not diagnostic on its own, it provides useful context in a comprehensive evaluation of gluten-related disorders.
Gliadin (AGA) IgG
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