What this test measures
Deamidated gliadin peptide (DGP) antibodies are directed against a chemically modified form of gliadin — a wheat protein. In genetically susceptible people, gut transglutaminase enzyme deamidates gliadin, creating modified peptides that the immune system attacks. DGP IgA measures this immune response.
It is the modern successor to older "anti-gliadin antibody" (AGA) tests, with much better specificity. DGP IgA is highly sensitive and specific for celiac disease, especially valuable in young children under 2 years (where the tissue transglutaminase / tTG test is less reliable) and in cases where tTG IgA is equivocal.
Why it matters
Celiac disease — once thought rare in India — is now recognised as common in the wheat-eating north (1–2% population prevalence in some studies). Symptoms range from classic (chronic diarrhoea, weight loss, growth failure in children, iron-deficiency anemia not responding to iron) to silent (osteoporosis, infertility, recurrent miscarriage, unexplained transaminitis). The only treatment is lifelong strict gluten avoidance.
Diagnosis requires both antibody testing and confirmation by upper GI endoscopy with duodenal biopsy showing villous atrophy. DGP IgA and tTG IgA are the modern first-line antibody tests. DGP IgA is particularly useful in: children under 2 (tTG less reliable), IgA-deficient patients (in whom DGP IgG is used), and equivocal tTG results.
How to prepare
No fasting required. Critical: do NOT start a gluten-free diet before testing. Antibodies fall and biopsy heals on a gluten-free diet, leading to false-negative results and missed diagnosis. Continue eating normal wheat-containing food (at least one slice of bread or equivalent daily) for at least 6 weeks before the test. Inform your doctor if you are IgA deficient — DGP IgG is then used instead.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| DGP IgA (U/mL (or AU/mL))[1][2][3] | Negative (assay-specific cut-off, typically < 20 U/mL) | Negative: low likelihood of celiac disease. If clinical suspicion is high, also check tTG IgA, total IgA (to exclude IgA deficiency), and consider DGP IgG. | Positive: suggests celiac disease. The higher the titer, the higher the probability. Confirm with duodenal biopsy showing villous atrophy (Marsh 3 lesion). Some paediatric guidelines now allow biopsy-free diagnosis when tTG IgA is > 10× upper limit of normal and a confirmatory antibody is also positive. |
Celiac disease antibody panel
| Antibody | Best use | Comment |
|---|---|---|
| tTG IgA | First-line in children > 2 and adults | Highest sensitivity and specificity overall |
| Total serum IgA | Excludes IgA deficiency (2–3% of celiacs) | Always test alongside tTG IgA |
| DGP IgA | Confirmation; under-2 children | Useful when tTG is equivocal |
| DGP IgG | IgA-deficient patients | Use when total IgA is low |
| Anti-endomysial (EMA) IgA | Confirmation | Highly specific; observer-dependent |
Frequently asked questions
Should I go gluten-free before this test?
No — that is the most common mistake. Antibodies fall and biopsy heals on a gluten-free diet, causing false-negative results. Continue normal wheat-containing food (at least one daily serving) for at least 6 weeks before testing.
What is the difference between DGP IgA and tTG IgA?
Both are celiac disease antibodies. tTG IgA is the first-line test for older children and adults. DGP IgA is more useful in children under 2 (tTG is less reliable at this age) and as a confirmatory test when tTG is equivocal or in IgA-deficient patients (DGP IgG variant).
Do I still need a biopsy if the antibody is positive?
For adults, yes — upper GI endoscopy with duodenal biopsy showing villous atrophy is the gold-standard confirmation. For children, modern paediatric guidelines (ESPGHAN) allow biopsy-free diagnosis if tTG IgA is > 10× upper limit of normal and EMA IgA is also positive.
How common is celiac disease in India?
Once considered rare, it is now recognised as common in wheat-eating regions — 1–2% prevalence in northern Indian populations. Most cases remain undiagnosed because of atypical or silent presentations.
What about IgA deficiency?
About 2–3% of celiac patients are IgA-deficient — they will have a false-negative IgA-based antibody test. Always check total serum IgA alongside any IgA-based celiac antibody. If IgA is low, switch to DGP IgG or tTG IgG.
What if my biopsy is negative but my antibody is positive?
This is uncommon but can happen with patchy disease or biopsy sampling error. Repeat biopsy from multiple duodenal sites, check the second antibody, and consider genetic testing (HLA-DQ2/DQ8). About 5% of patients have "potential celiac disease" with positive antibodies and normal biopsy — they need follow-up.
Related Immunology tests
Tests commonly ordered alongside ANTI DEAMIDATED GLIADIN PEPTIDE - IGA, or that help interpret an unexpected result.
Sources & references
- NCBI StatPearls — Celiac Disease · accessed 2026-05-30T00:00:00.000Z
- ACG Clinical Guideline — Celiac Disease · accessed 2026-05-30T00:00:00.000Z
- Mayo Clinic Labs — Deamidated Gliadin Peptide IgA · accessed 2026-05-30T00:00:00.000Z
- NIH MedlinePlus — Celiac Disease Tests · accessed 2026-05-30T00:00:00.000Z
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