DGP IgA

If you have unexplained digestive symptoms, a family history of celiac disease, or low levels of a key antibody class called IgA, this test offers a second window into whether your immune system is reacting to gluten. It can pick up signs of celiac disease that the most common screening test sometimes misses, particularly in young children, in people with IgA deficiency, and during follow up of a gluten free diet.

DGP IgA (deamidated gliadin peptide IgA) measures one piece of the immune response to gluten. It works best when paired with the standard celiac antibody test, and the pattern of results, more than any single number, tells you whether further investigation is warranted.

What This Test Actually Measures

Gluten contains a protein called gliadin. Inside the small intestine, an enzyme called tissue transglutaminase chemically tweaks gliadin in a process called deamidation. The tweaked fragments stick more strongly to immune cells and provoke a stronger antibody response in people who are sensitive to gluten.

DGP IgA is an immunoglobulin A antibody (one of several antibody types your body makes) that targets these tweaked gluten fragments. The test reads how much of this antibody is circulating in your blood. A high level signals that your immune system is actively reacting to gluten in a way that is characteristic of celiac disease.

Why It Matters

Celiac Disease Detection

Celiac disease is an autoimmune condition where gluten triggers damage to the lining of the small intestine. Left undiagnosed, it can cause nutrient deficiencies, bone loss, infertility, and an increased long term risk of certain cancers and cardiovascular disease, according to a Danish cohort of 16,776 adults.

In adults with a high suspicion of celiac disease, DGP IgA performs nearly as well as the standard tissue transglutaminase IgA test, with one prospective study reporting an area under the curve of 0.995 for DGP IgA compared with 0.996 for tTG IgA. In children, sensitivity for DGP IgA has reached around 92 percent with specificity near 98 percent in dedicated assay studies.

Catching Disease Earlier

In genetically at risk infants and toddlers, DGP antibodies often appear 6 to 12 months before tTG IgA turns positive. A meta analysis of children under age two found that adding DGP testing improved sensitivity beyond tTG IgA alone, even though tTG IgA remained the single best test in that age group.

Roughly 10 percent of biopsy proven celiac disease cases in some adult series were tTG IgA negative but DGP positive. If you have classic symptoms but a normal tTG result, DGP testing can help avoid a missed diagnosis.

Detecting Celiac in IgA Deficiency

About 1 in 500 people produce very little IgA, which makes the standard IgA based celiac tests unreliable. In these individuals, the IgG version of the DGP test (an antibody class your body still makes normally) is the more useful read. The IgA version of DGP can still be checked, but if your total IgA is low, the IgG version is what carries the diagnostic weight.

Monitoring a Gluten Free Diet

Once you start a gluten free diet, DGP antibodies tend to fall as the gut heals. Studies suggest the combined IgA and IgG DGP test can be more sensitive than tTG IgA for spotting persistent gut damage and dietary slip ups, while still keeping high specificity. A point of care DGP test detected ongoing villous atrophy (the flattening of the gut lining seen in celiac disease) more reliably than other surrogate markers in 217 patients on a gluten free diet.

How DGP IgA Compares to Other Celiac Tests

DGP IgA is one of several blood markers used in celiac disease workups. The choice of test depends on your IgA status, age, and clinical question.

Source: Niveloni et al. 2007; Novis et al. 2023; Catassi et al. 2021; Husby et al. 2020 ESPGHAN guidelines.

What this means for you: a normal tTG IgA does not always rule out celiac disease, especially in young children, in people with IgA deficiency, or when symptoms are strongly suggestive. Pairing DGP with tTG and total IgA gives a more complete picture than any one marker alone.

Reference Ranges

DGP IgA cutpoints are not fully standardized across labs. Different manufacturers use different units (often U/mL) and define the upper limit of normal differently, so the same blood sample can produce different numeric results in different laboratories. The categories below describe how DGP IgA is generally interpreted in clinical practice. Compare your result within the same lab over time for the most meaningful trend.

Compare your results within the same lab over time. A rising or persistently elevated value carries more weight than a single number near the threshold.

Reconciling a Counterintuitive Truth

You may notice that an isolated positive DGP IgA, with a normal tTG IgA, often does not mean you have celiac disease. In one pediatric series, only 1 of 40 children with this pattern had biopsy proven celiac disease, a positive predictive value of 2.5 percent. Another large pediatric cohort found DGP specificity of just 26 percent compared with 86 percent for tTG.

This is not a contradiction. DGP and tTG measure related but different parts of the immune response. Isolated DGP positivity can reflect a transient or low grade immune reaction to gluten that is not yet causing the gut damage that defines celiac disease. The combined pattern of DGP plus tTG is what carries diagnostic weight, not either marker alone.

When Results Can Be Misleading

• IgA deficiency: if your total IgA is low, your DGP IgA may be artificially low or undetectable even if you have celiac disease. The DGP IgG version of the test, or IgG tTG, is the right read in this situation.
• Already on a gluten free diet: if you have been avoiding gluten before testing, antibody levels can fall and produce a falsely negative result. For accurate diagnosis, gluten exposure for several weeks before testing is typically needed.
• Isolated low level positivity: in low risk people without symptoms, a slightly elevated DGP IgA with a normal tTG IgA is more often a false positive than a sign of disease, particularly in children.
• Lab to lab variation: different DGP IgA assays can give different numeric results for the same sample. Track your trend within one lab when possible.

Tracking Your Trend

A single DGP IgA result is a snapshot. The bigger story is whether your level is rising, falling, or staying stable over time. If you are testing because of suspected celiac disease, the change after a gluten free diet is itself diagnostic information: levels typically fall over months as the gut heals.

A reasonable cadence: get a baseline if you have symptoms, a family history of celiac disease, or another autoimmune condition like type 1 diabetes. If you start a gluten free diet, recheck in 3 to 6 months and again at 12 months to confirm levels are normalizing. After that, an annual check is appropriate, with more frequent testing if symptoms return.

What to Do If Your Result Is Abnormal

A positive DGP IgA is the start of an investigation, not a diagnosis. The decision pathway depends on the pattern of your results and your symptoms.

• Order tTG IgA and total IgA together: these are the companion tests that give your DGP result context. Combined high titers of tTG IgA and DGP IgG can support a non biopsy diagnosis in adults, while isolated DGP positivity with normal tTG usually means a low likelihood of celiac disease.
• See a gastroenterologist: if both DGP and tTG are elevated, a duodenal biopsy is the standard next step to confirm celiac disease and assess the extent of intestinal damage.
• Genetic testing in selected cases: HLA DQ2 and DQ8 testing is rarely needed but can help when serology is unclear. A negative HLA test makes celiac disease very unlikely.
• Do not start a gluten free diet before further testing: removing gluten can lower your antibody levels and obscure the diagnosis. Wait until your evaluation is complete.