Coeliac disease tests are used to screen for and help diagnose coeliac disease and a few other gluten-sensitive conditions (such as dermatitis herpetiformis, a condition that causes an itchy burning blistering rash on the skin). They are usually requested on those patients with symptoms suggesting coeliac disease, but may also be requested to help rule out coeliac disease as a cause for conditions such as anaemia and abdominal pain.
Testing may be performed to screen for coeliac disease in people who do not have symptoms, but who do have close relatives with coeliac disease. About 10% of people who have close relatives with coeliac disease will develop it themselves. Coeliac disease tests may also be requested in people who have other autoimmune diseases such as type 1 diabetes mellitus, or thyroid disease as patients with autoimmune diseases often have more than one autoimmune disease.
A doctor may use one or more coeliac disease tests, along with tests to evaluate the status and extent of a patient’s malnutrition and malabsorption. Currently there are two main autoantibodies related to coeliac disease that are measured in the laboratory. IgA Anti-tissue Transglutaminase Antibody (TTG) is usually the first choice test in the UK. If the result of this is equivocal (uncertain), IgA antiendomysial antibody (EMA) would then be measured. If both the anti-TTG and anti-EMA are negative but the doctor still suspects coeliac disease, they may request other tests that include:
serum IgA level, as about 2-3% of coeliac disease patients are IgA-deficient
IgG anti-TTG and/or IgG EMA if IgA deficiency is confirmed
If the results of autoantibody testing are positive, or if clinical suspicion remains high inspite of negative findings, the patient should be referred to a gastrointestinal specialist to undergo biopsy of the small intestine (gut) to confirm or exclude the diagnosis of coeliac disease.
When a patient with coeliac disease has been on a gluten-free diet for a period of time, autoantibody concentrations should decrease. The improvement in symptoms, together with disappearance of the autoantibodies from the blood is a good marker of improvement in the inflammation in the gut wall. When a patient’s symptoms have not subsided, coeliac disease tests may be used to check for dietary compliance, and if they remain positive they may guide the doctor and patient to look either for hidden gluten in the patient’s diet or for other reasons for their unrelieved symptoms.
Other tests may be performed to help determine the severity of the disease and the extent of a patient’s malnutrition, malabsorption, and organ involvement. These might include a:
In general, if your anti-TTG test result is at least moderately or strongly positive, then it is likely that you have coeliac disease. False positive results can however be found and this is the reason for checking anti-EMA, and sometimes performing a small intestinal biopsy.
If the anti-TTG IgA test result is negative, then it is most likely that you do not have coeliac disease. However, your anti-TTG IgA concentrations may be very low or undetectable if you have been avoiding wheat, rye, and barley for a period of time or if you are one of the small percentage of patients with coeliac disease who are also deficient in IgA. This may lead to a false negative result and may prompt your doctor to perform additional testing.
If the anti-EMA IgA is positive but the anti-TTG IgA autoantibody is negative, then it is still possible you may have coeliac disease. Hence if the blood test results are equivocal (uncertain), your doctor may consider an intestinal biopsy to confirm or rule out coeliac disease.
If you have been diagnosed with coeliac disease and have removed gluten from your diet, then your autoantibody concentrations should fall. If they do not, and your symptoms do not diminish then there may either be hidden forms of gluten in your diet that have not been eliminated (gluten is often found in unexpected places, from salad dressings to cough syrup) or you may have one of the rare forms of coeliac disease that does not respond to dietary changes. In most cases, when celiac disease tests are used to monitor progress, rising concentrations of autoantibodies indicate some form of non-compliance with a gluten-free diet.
If you have changed your diet, eliminating gluten days or weeks prior to visiting your doctor, then your coeliac disease autoantibodies may not be detectable. In this case your doctor may do a gluten challenge – have you put gluten back into your diet for several weeks or months to see if the symptoms return, then recheck autoantibodies, and consider whether a biopsy of the intestine is necessary.
Although coeliac disease is relatively common (about 1 in 100 people in the Europe are thought to be affected) most people who have the disease are not aware of it. This is partly due to the fact that the symptoms are variable and may be mild or absent, even when intestinal damage is present in the gut wall. Since these symptoms may also be due to a variety of other conditions a diagnosis of coeliac disease may be missed or delayed.
This article was last reviewed on 7 September 2011. | This article was last modified on 27 October 2011.
The review date indicates when the article was last reviewed from beginning to end to ensure that it reflects the most current science. A review may not require any modifications to the article, so the two dates may not always agree.
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