What are deamidated gliadin IgG antibodies?
Deamidated gliadin IgG antibodies are immunoglobulins that are formed by the body's immune system in response to gluten ingestion, specifically against a modified form of the protein gliadin found in wheat, rye and barley. When processed in the body, gliadin is converted to deamidated gliadin, which can trigger an autoimmune reaction in some individuals. These antibodies are particularly relevant in the investigation of celiac disease (gluten intolerance) and are often used as a complement to other antibody tests such as transglutaminase IgA or endomysium antibodies.
Why are deamidated gliadin IgG antibodies analyzed?
The analysis is primarily used to identify immunological reactions to gluten in people suspected of having celiac disease, especially if the patient has IgA deficiency, which can complicate the interpretation of standard IgA-based tests. Deamidated gliadin IgG is more specific than older tests against natural gliadin, and is therefore used in modern diagnostics as an aid in detecting celiac disease even in atypical symptoms or in adults with long-term gastrointestinal symptoms.
How does IgG differ from IgA in gluten testing?
In celiac disease testing, transglutaminase IgA is the primary marker, but some individuals have a congenital IgA deficiency, which means that this analysis can give false negative results. In these cases, deamidated gliadin IgG is used as an alternative or complement. The detection of IgG antibodies provides an important clue to immune activation against gluten in patients where traditional tests are not reliable.
What does a positive test result for deamidated gliadin IgG mean?
A positive test result indicates that the body has developed IgG antibodies against deamidated gliadin, which indicates an immunological reaction to gluten. This strengthens the suspicion of celiac disease, especially in combination with symptoms such as diarrhea, weight loss, malnutrition or fatigue. However, the result should always be interpreted in relation to other clinical and laboratory findings and preferably followed up with a small intestinal biopsy for definitive diagnosis.
Reference values for deamidated gliadin IgG
Reference values may vary slightly depending on the laboratory and analysis method, but generally the following limits apply:
- Negative: < 10 U/mL
- Cutoff value: 10–20 U/mL (should be followed up or assessed in combination with other tests)
- Positive: > 20 U/mL
It is important that the sample is taken during a gluten-containing diet for the result to be reliable. On a gluten-free diet, the levels can drop and lead to a false negative result.