OVERVIEW
What is a celiac disease?
It is an autoimmune disorder where body produces inappropriate immune response against gluten i.e. a protein found in wheat, & related dietary proteins in barley and rye. Celiac disease & few other gluten-sensitive diseases can be diagnosed & monitored via antibody tests which look for autoantibodies in the blood. Various antibodies are measured for its amount found in blood that help in differential diagnosis of celiac disease. These antibody tests include tTG IgA, IgA, tTG IgG, & DGP antibodies IgA/IgG.
What is anti-gliadin IgA (anti-DGP) lab test?
This test is used for quantitative determination i.e. measures amount of IgA antibodies released against DGP (deaminated gliadin peptide epitopes) in human blood (plasma or serum). Gliadin is one of the main proteins found in gluten which is deaminated by tTG (tissue transglutaminase) and release DGP fragments. Then against this DGP, antibodies are initiated as an extensive immune response.
Why is anti-gliadin IgA (anti-DGP) lab test done?
The test is done:
- To detect antigliadin antibodies & help in diagnosis and monitoring of gluten-sensitive conditions like celiac disease or dermatitis herpetiformis (chronic intensely itchy blistering skin)
- It helps in detection of gliadin involvement in medical condition
- Used in celiac disease suspected patients, symptomatic patients, atypical symptom patients, & those at increased risk of disease
- When patient suspects celiac disease but is negative for anti-tTG which especially occurs in children younger than 2 years
- Positive anti-DGP test is used to monitor celiac disease
- Screen celiac disease in individuals with IgA deficiency
- Used in people with negative test for EMA antibodies (anti-endomysial antibodies)
- IgA antibody detection is useful for celiac disease as it is made in small intestine, where gluten supposedly causes irritation & inflammation in sensitive individuals
- Is fasting required while going for celiac panel blood test?
If for diagnosis, the continue eating food with gluten in it for some period prior to testing. If for monitoring, then no preparation is needed
- How long should you eat gluten before celiac blood test?
Eating a little gluten each day like having a slice of regular bread or two for a week or ten days, is helpful for producing antibodies which can be diagnosed by the doctor later in the test
- In celiac disease, is IgA high or low?
There are only about 3% people with celiac disease and IgA deficiency both. So, if serum IgA tTG result comes negative and there is strong suspicion of disease, then serum total IgA levels are measured
- What is a celiac attack like?
People sensitive to gluten/celiac disease have symptoms like bloating, gas, diarrhea (loose motions), anemia (low hemoglobin), & growth issues
- How long does antibodies against gluten stay in blood?
Depends upon which antibody test is done. In case of tTG, there half-life is of 6 months in the blood.
INTERPRATATION OF THE RESULTS:
The ranges interpret the following:
- < 20.0 U: Negative; indicates reduced likelihood of having celiac disease
- 0 to 30.0 U: Weakly positive
- >30.0 U: Positive; indicates that celiac disease is present and is consistent with diagnosis of celiac disease
NOTE: If DGP IgA or IgG antibodies reduce after following treatment and gluten-free diet, then it means adherence to diet. Whereas if there are persistent high levels of these antibodies after following dietary treatment, it means poor adherence or there is presence of refractory disease (disease that does not respond to treatment).
You get tested when you suspect having celiac disease, if patients are showing symptoms of celiac disease, patients with atypical symptoms, & in people with increased risk of celiac disease. It also helps in evaluation of treatment response with gluten-free diet.