How is celiac disease diagnosed?

Dr. Patricia L. Raymond, MD

The first step to a diagnosis of celiac disease is awareness, either from you or your doctor. I test for celiac whenever it crosses my mind, most specifically for my patients with IBS-like bowel symptoms, or if my patients have any of the collateral diseases, or have a family member with celiac disease.

Testing is simple—a blood test (Tissue Transglutaminase IgA and Total IgA are my favorites, although a more extensive celiac panel is available). A positive test is followed by a confirmatory upper endoscopy with small intestine biopsy to look for flattening or inflammation of those villi. The biopsy is the gold standard still, despite our excellent blood test. I choose to formalize the diagnosis with biopsy, because being off gluten in our wheat-based world is a major hassle.

Dr. Robynne K. Chutkan, MD

Doctors can diagnose celiac disease by considering risk factors and test results:

  • Family history; if you have a first-degree family member who is diagnosed with celiac disease, your chances of having the condition are between 10 and 20 percent.
  • The simplest screening tool is a blood test that can check for antibodies associated with the disease. More sophisticated blood tests can also check to see if you belong to one of the genetic groups more likely to develop celiac disease.
  • The most accurate test is a biopsy of the small intestine, which is obtained during a procedure called an upper endoscopy where you are given a sedative and a small tube is inserted through the mouth into the upper part of the small intestine. The test is safe and painless and is the "gold standard" for definitively diagnosing celiac disease. It's important to eat lots of gluten-containing foods for a few weeks prior to testing to increase the accuracy of the tests.

Celiac disease is diagnosed by testing your blood, taking a sample of skin or small intestine, and trying a doctor-supervised gluten-free diet. When you have celiac disease your body produces extra amount of antibodies to fight the gluten that it thinks is an unwanted substance to the body. Due to celiac disease's affect on absorbing nutrients, it also causes vitamin and iron deficiencies. Both the extra antibodies and the deficiencies can be seen in blood tests ordered by your doctor.

Another way to confirm a diagnosis of celiac disease is to have a sample of your intestines removed through a procedure called a biopsy. Once the sample is obtained it is evaluated under a microscope to look for damage to the lining of the intestines. Nearly 25 percent of people affected with celiac disease also have a rash called dermatitis herpetiformis, a skin biopsy of this rash can test for elevated antibodies on the skin and along with blood tests can diagnose celiac disease.

To confirm a diagnosis of celiac disease a doctor may put you on a gluten-free diet to see how your body responds. It is important to wait for a doctor's supervision before switching your diet because changing your diet before you have had the diagnostic tests for celiac disease may skew the results of your tests.

Symptoms of celiac disease are often similar to those of other digestive diseases making it difficult to diagnose, which is why some patients go undiagnosed for years. However, new diagnostic methods are facilitating faster and more accurate diagnosis.

If celiac disease is suspected, your physician will take a blood sample and test it for certain antibodies, including:

  • anti-gliadin antibodies
  • anti-endomysial antibodies
  • anti-tissue transglutaminase antibodies
  • total immunoglobulin A levels

Your physician will also want to determine whether any nutritional deficiencies exist, such as iron, folate (a B-vitamin), vitamin B-12, calcium and vitamin D, as well as copper and zinc levels.

You may also have an endoscopic examination of your small intestine, where biopsies of the duodenum will be taken to look for changes characteristic of celiac disease.

Celiac disease is diagnosed by compiling a thorough history of the condition. Doctors will also perform a physical exam, blood tests and upper gastrointestinal endoscopy with biopsies to diagnose celiac disease.

Dr. Donald J. Brust, MD

If your doctor suspects that you have celiac disease, he or she will likely perform a series of blood tests to detect the presence of antibodies that occur in response to repeated exposure to gluten-containing substances. More than 90 percent of patients who have untreated celiac disease will test positive for one or more of these antibody tests. With most tests, it is important that patients continue to consume a normal, unrestricted diet prior to testing. Consumption of a gluten-free diet prior to testing can cause a false-negative test which could delay diagnosis. For those patients who are already consuming a gluten-free diet, a blood test can also be done to detect a protein marker that exists on the cells in your body. This test is most useful when negative as it excludes the possibility of celiac disease; if positive, it means simply that celiac disease is possible for the patient's symptoms and that further testing is necessary. If blood tests are positive, you should undergo upper endoscopy, which allows your doctor to examine the small bowel and obtain biopsies to confirm the diagnosis. The test itself is painless and no recovery period is required.

Trinity Health is a Catholic health care organization that acts in accordance with the Catholic tradition and does not condone or support all practices covered in this site. In case of emergency call 911. This site is educational and not a substitute for professional medical advice, always seek the advice of a qualified healthcare provider.

Celiac disease can be diagnosed with a simple blood test to look for celiac disease antibodies. People with celiac disease who eat gluten have higher-than-normal levels of these antibodies in their blood. You must be on a gluten-containing diet for antibody (blood) testing to be accurate.

The most sensitive and commonly used test, whether symptoms are present or not, is the tissue transglutaminase antibodies (tTG-IgA) test. Other antibody tests are available to double-check for potential false positives or false negatives, including:

  • IgA endomysial antibody (EMA): The EMA test has a specificity of almost 100%, but it is not as sensitive as the tTG-IgA test. About 5%-10% of people with celiac disease do not have a positive EMA test. It is also very expensive in comparison to the tTG-IgA and requires the use of cells from a primate esophagus or human umbilical cord. It is usually reserved for people who are difficult to diagnose.
  • Total serum IgA: This test is used to check for IgA deficiency, a harmless condition associated with celiac disease that can cause a false negative tTG-IgA or EMA result. If you are IgA deficient, your doctor can order a DGP or tTG-IgG test.
  • Deaminated gliadin peptide (DGP IgA and IgG): This test can be used to further screen for celiac disease in individuals with IgA deficiency or people who test negative for tTG or EMA antibodies.

While it is very rare, it is possible for someone with celiac disease to have negative antibody test results. If your tests were negative but you continue to experience symptoms, consult your doctor and undergo further medical evaluation. Genetic testing can be used to rule out celiac disease.

Keep in mind that positive antibody or genetic test results only suggest the presence of celiac disease—the test results cannot confirm it. If these screening tests come back positive, the next step in diagnosing celiac disease is to get a biopsy of the small intestine.

Celiac disease is diagnosed initially with a blood test that is then confirmed by a biopsy specimen obtained from the small intestines during an upper endoscopy (EGD). If your blood test is positive, a gastroenterologist will confirm the diagnosis by looking for “blunting of villi” on upper endoscopy biopsies. Villi are tiny, finger-like projections that line the small intestines; villi are lost or blunted in the setting of celiac disease due to an allergic reaction to foods containing gluten.
Dr. Troy D. Schmidt, MD

Celiac disease is an autoimmune disease that causes damage to the body when gluten, found in wheat products like bread, pasta and pastries, is consumed. Celiac disease is diagnosed by drawing a blood test called a celiac panel, which tests for the celiac antibody. It is then confirmed by doing an endoscopic biopsy of the small intestine to confirm the presence bowel destruction from the celiac disease. Symptoms of celiac disease include diarrhea and weight loss (due to malabsorption), abdominal pain, bloating and flatus. Patients are typically placed on a gluten free diet where symptoms are noted to resolve.

Endoscopy can be used to identify a change in the lining of the small intestine that occurs with celiac disease.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.