Deamidated Gliadin Peptide (DGP)
This is a blood test that helps your doctor investigate coeliac disease, an immune reaction to gluten. It is especially useful in young children, and in people who make too little of the antibody the main coeliac test relies on. Like all coeliac tests, it only counts if you are still eating gluten. A positive result is a prompt for the next step, not a diagnosis.
Standard CareWhat is deamidated gliadin peptide (dgp)?
Deamidated gliadin peptide (DGP) is a serology test — a blood test that looks for an antibody (a protein made by the immune system). Gliadin is one of the components of gluten, the protein found in wheat, rye, and barley. In coeliac disease (a genetic autoimmune condition where the immune system reacts to gluten and damages the small bowel lining), the body can make antibodies against a modified, "deamidated" form of gliadin — and the DGP test measures those antibodies. DGP is usually measured as the IgG type (DGP-IgG). This is helpful because the main first-line coeliac test, tissue transglutaminase IgA (tTG-IgA), depends on the IgA antibody class — and some people do not make enough IgA. The DGP-IgG assay has replaced an older anti-gliadin antibody (AGA) test because it is more specific, and unlike the IgA-based tests it is not thrown off by IgA deficiency. DGP is one of several coeliac antibody tests your GP can use, alongside tTG-IgA, total IgA, and — for confirmation — endomysial antibodies (EMA) and a small-bowel biopsy.
Why is it tested?
DGP testing is used when coeliac disease is being investigated, usually together with tTG-IgA. Australian practice pairs the two — adding DGP-IgG enhances the detection of coeliac disease by about 15% compared with tTG-IgA alone — and DGP is particularly valuable in two groups: people with low total IgA (in whom IgA-based tests can falsely come back negative), and very young children, in whom tTG-IgA can be less reliable. As with every coeliac blood test, the result is only meaningful if you have been eating a normal, gluten-containing diet beforehand. Coeliac Australia is explicit that testing should confirm the person is consuming a gluten-containing diet for accurate results. Starting a gluten-free diet first can lower the antibodies and produce a falsely negative result.
Reference range (Australia)
The cut-off for a positive DGP result varies by laboratory and assay — there is no single national standard. The reference interval printed on your own laboratory report is the correct one to use; do not compare your number with a cut-off from a different lab or a general website.
Reference intervals vary between laboratories. Always use the range printed on your own report.
What your result means
A negative (low) DGP result makes active coeliac disease less likely, particularly when your tTG-IgA is also negative. No coeliac blood test is perfect, though — serology can occasionally miss the condition — so a negative result does not completely rule it out if you have strong symptoms or a family history. Two things can produce a falsely negative result: having already started a gluten-free diet before the test, and (for the IgA-based tests) a low total IgA. DGP-IgG is useful precisely because it is not affected by IgA deficiency. If suspicion remains, your GP can advise on next steps.
A normal DGP result, read alongside your other coeliac tests, is generally reassuring — provided you were eating gluten at the time. If your symptoms persist, it is worth a conversation with your GP, who will weigh the whole picture rather than a single antibody.
A positive (raised) DGP result means your immune system is producing antibodies against deamidated gliadin — a pattern associated with coeliac disease in someone who has been eating gluten. The higher the level, the greater the concern, but the number alone does not confirm a diagnosis. A positive coeliac antibody result is not enough to diagnose coeliac disease on its own. It is a prompt for the next step. Australian guidance is to refer to a gastroenterologist (a gut specialist) for a confirmatory small-bowel biopsy, where a small sample of the gut lining is checked. Your GP will read the DGP alongside your tTG-IgA, total IgA, and symptoms, and explain what the result means for you.
What can affect your result
Gluten intake is the most important factor. DGP reflects an active immune response to gluten, so the test is only reliable when it is done while you are eating a normal gluten-containing diet, which is why your GP advises continuing gluten until coeliac testing is complete. Going gluten-free beforehand lowers the antibodies and is the most common reason for a falsely negative result. The antibody class matters too. DGP is usually measured as DGP-IgG, which — unlike the IgA-based tTG-IgA — is not adversely affected by IgA deficiency. This is why DGP-IgG is often added when total IgA is low, and why pairing it with tTG-IgA picks up more cases of coeliac disease than tTG-IgA alone. Age is a consideration: in very young children, the standard tTG-IgA test can be less reliable, and DGP-IgG is used alongside it. Because DGP is one of several coeliac markers, your GP always interprets it together with your tTG-IgA, total IgA, symptoms, and — where needed — specialist assessment, rather than on its own.
When to act
If your DGP is positive, your GP will review it alongside your tTG-IgA and total IgA and consider referral to a gastroenterologist for a confirmatory small-bowel biopsy — the step that confirms or rules out coeliac disease. One thing worth knowing: going gluten-free before that assessment is complete can lower the antibodies and make coeliac disease harder to pin down, so your GP will guide the timing. If your DGP is negative but you still have symptoms that concern you — or a family history of coeliac disease — raise this with your GP, who will consider whether you were eating gluten before the test and whether further investigation is warranted. This page is general information and is not a substitute for advice from your GP.
Frequently asked questions
Test your deamidated gliadin peptide (dgp)
NATA-accredited testing. Results in 2–5 days. No GP referral required.
View Coeliac Screen