Testing for Gluten Allergy
Mary Pickett, M.D., is a lecturer for Harvard Medical School and an assistant professor of medicine at Oregon Health & Science University in Portland, OR. At OHSU, she practices general internal medicine and teaches medical residents and students.
What is gliadin antibody (IGA and IGG). And what is a normal range for a 42-year-old female?
In the past decade, gluten allergy has received a good deal of attention as a cause of abdominal and other symptoms, as well as vitamin and iron deficiencies.
True gluten allergy is called celiac disease or "celiac sprue". Here, your body makes a collection of antibodies after you eat grains or carbohydrates that contain gluten. All foods that contain wheat, barley, or rye grains also contain gluten. Small quantities are found in oats, too.
Gluten allergy is not like most other allergies. That's because the antibodies that are produced after exposure do not trigger typical allergy symptoms (such as hives or wheezing). Instead, they cause a subtle change in the health of the intestine, resulting in poor digestion. Gluten allergy may also trigger symptoms of fatigue, mouth sores, numbness or tingling in the skin, a blistering rash, and thinning of the bones.
There are several blood tests that doctors use to determine gluten allergy.
The test you had, the "gliadin" antibody test, is sometimes used as a screening test for celiac disease. The test is usually positive in people with true gluten allergy. But the test is not specific. This means that many people with gliadin IgA or IgG antibodies don't actually have celiac disease. Doctors call this a false positive.
If a gliadin antibody blood test is used as an initial test for gluten allergy, then it may help to have additional testing. The two most helpful blood tests to diagnose celiac disease are "tissue transglutaminase" (TTA) IgA antibody and "endomysial" IgA antibody tests.
Antibody tests are usually reported as a "titre." This is a concentration of antibody in the blood that is reported as "units per milliliter." For example, a gliadin test that comes back with a value that is higher than 25 or 30 units would usually be considered abnormal. However, this would not mean you definitely have celiac disease or even gluten sensitivity. You'd need more testing to confirm a diagnosis.
The gold standard test to diagnose celiac disease is biopsy of the lining of the intestine. This is done during an upper endoscopy.
To treat true gluten allergy, you must change your diet to completely avoid gluten.
Some people who do not have celiac disease (i.e. a true allergy to gluten) report that going gluten-free makes them feel more physically "well." Instead of having gluten "allergy" these people have gluten "intolerance."
We don't have a good understanding of gluten intolerance. People with gluten intolerance use trial and error to see how much gluten they should avoid to feel well. They don't necessarily need to avoid all gluten.
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