What Your Celiac Test Results Mean

Celiac disease is an autoimmune condition. When someone with celiac disease eats gluten, their immune system damages their intestine. Gluten is a protein found in grains, like wheat, rye, and barley. 

Without treatment, celiac disease can cause symptoms such as diarrhea and weight loss. Over time, it can lead to more serious nutritional problems. But even though celiac disease is common, it’s not easy to figure out if someone has it. That’s because only about 20% of people with celiac disease have early symptoms. And testing for celiac disease isn’t straightforward. 

What are the different kinds of tests for celiac disease?

Figuring out whether you have celiac disease can be a frustrating process. Like most autoimmune conditions, there isn’t just one specific test that can give you a diagnosis. Instead, you need to combine several different tests. These include:

• Antibody tests

• Genetic tests

• Endoscopy with biopsy

• Gluten challenge

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Sometimes all the test results fit together and give a clear diagnosis. But in other cases the results are not so straightforward. So getting a diagnosis can take time and more than one round of testing. 

Antibody tests 

An antibody test is a blood test that looks for celiac-specific antibodies. When someone with celiac disease eats gluten, their immune system makes antibodies against gluten. There are different types of antibody tests. When you use them together, the results help figure out if you have celiac disease. These antibody tests are:

• Anti-tissue transglutaminase IgA antibody (tTG-IgA): This is one of the most important tests for celiac disease. If your test is positive there’s a very high chance that you have celiac disease. 

• IgA endomysial antibody (EMA): Not everyone with celiac disease makes this antibody against gluten. But it’s helpful to rule out celiac disease. Research shows that if you don't make this antibody, it’s very likely you don’t have celiac disease. 

• Total serum IgA: This test isn’t specific for celiac disease. It measures how much IgA antibodies your body makes at baseline. This is important because people who don’t make IgA might not make tTG-IgA antibodies even if they have celiac disease. If your IgA level is too low, the results of your other tests may be falsely negative.

One thing to keep in mind, these antibody tests are only reliable if you’re still eating gluten. So your healthcare provider will ask you to keep eating gluten until you’ve finished testing. 

Endoscopy

Along with antibody tests, you’ll need a biopsy of your small intestine to know if you have celiac disease. A small intestine biopsy will accurately show if your immune system is attacking your small intestine. 

A small intestine biopsy is done with an endoscopy. During an endoscopy, a healthcare provider passes a scope with a small camera from your mouth into the stomach and small intestine. The camera can show damage and inflammation in real time, and tiny forceps can take tissue samples at the same time. 

An endoscopy is a medical procedure that requires anesthesia. It’s more invasive and expensive than blood tests. That’s why you’ll have antibody testing first. And if the results suggest celiac disease, only then will your provider offer an endoscopy to confirm that you have celiac disease.

In some cases, people can do a “video capsule endoscopy” (VCE) instead of a regular endoscopy. For a VCE, you swallow a small capsule with a camera inside it. The camera takes pictures of your small intestine as it passes through your intestines. 

Genetic tests

Celiac disease tends to run in families. There are two genes associated with celiac disease: HLA DQ2 and HLA DQ8.

People with celiac disease carry one or both of these genes. A genetic test checks your blood for these genes. If you don’t carry one of these genes (your test is negative), it’s likely you don't have celiac disease. 

Genetic testing is expensive and can cost hundreds of dollars. So, most of the time, providers only use these tests when it’s hard to tell if someone has celiac disease. 

If celiac disease runs in your family, you might be thinking about getting genetic testing. If you test negative, it means you have no chance of getting celiac disease in the future. 

But if you test positive for the genes, it does not necessarily mean that you will develop celiac disease. Almost 1 out of 3 people have these genes, but less than 5% of them actually develop celiac disease. So just carrying the genes doesn’t mean you’ll definitely develop celiac disease.

Gluten challenge 

If you’re already started on a gluten-free diet, your healthcare provider may suggest a gluten challenge before doing any tests. This lets you build up antibodies to gluten so your antibody tests and endoscopy results are more accurate. 

During a gluten challenge you’ll eat a specific amount of gluten every day for about 8 weeks. Most of the time, two slices of bread each day is enough for people to start making antibodies. 

How do you definitively diagnose celiac disease?

Figuring out if someone has celiac disease can be difficult. Not only do people experience different symptoms, some people don’t have symptoms at all. And test results can also vary from person to person. 

If you have positive antibody tests and your intestine biopsy results show inflammation, then it’s clear you have celiac disease. 

But not everyone has these same clear-cut results. Some people make antibodies but have no inflammation, or vice versa. Some people have symptoms of celiac disease and carry celiac genes but don’t make antibodies. 

With situations like these, healthcare providers often go by the “four-out-of-five rule.” That means someone likely has celiac disease if they meet four out of the five criteria below:

• Symptoms of celiac disease

• Positive antibody tests

• Positive genetic testing

• Intestinal damage on biopsy

• Improvement of symptoms with a gluten-free diet

Bottom line 

Knowing whether or not you have celiac disease will keep you healthy. But it can be tricky to get a diagnosis because testing isn’t perfect. Testing options include blood tests, endoscopy, genetic testing, and gluten challenges. Taken together, these results can diagnose you with celiac disease and help you find a diet plan that works for you. 

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Written by:

Ronald W. Dworkin, MD, PhD

Ronald W. Dworkin, MD, is a board-certified anesthesiologist who has been practicing anesthesiology in a community hospital for 30 years. He has taught in the honors program at George Washington University for over 10 years and works as a senior fellow at the Hudson Institute.

Edited by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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