How Doctors Diagnose Celiac Disease and Gluten Sensitivity
There's no simple test to tell if you have celiac disease or gluten sensitivity. The key is whether your body reacts to gluten. It's a protein found in wheat, rye and barley. Eating foods with gluten can cause:
- Abdominal pain
- Bone or joint pain
- Chronic fatigue
- Trouble focusing, or other ADHD-like behavior
The tricky part comes when you realize many other health problems can also cause these symptoms. They could be signs of irritable bowel syndrome, iron-deficiency anemia, intestinal infections, or chronic fatigue syndrome.
Because of these possibilities, doctors use several tests to tell whether gluten is the true source of the problem.
Diagnosing Celiac Disease
Celiac disease can develop at any age after you start eating foods that contain gluten. Bread, cereal and pasta are examples. Here's why.
Eating such foods causes problems in the digestive system. Inflammation damages or destroys the villi in the small intestine. They're tiny hair- or finger-like projections that line the intestine. They help the body absorb nutrients from food. However, they can't do that when they're damaged. This means your body can’t digest food right. You don't get the nutrition you need. Symptoms like diarrhea can develop.
These changes are what doctors look for if they think someone might have celiac disease. They follow three steps:
Test your blood for certain proteins
Look in your small intestine for damage
Look for other clues including family history
1. Testing Blood for Celiac Disease
If you have celiac disease and eat foods with gluten, your blood will have high levels of certain proteins called antibodies. This happens because your immune system sees gluten as a threat and makes extra antibodies to fight it.
Three antibodies are common with celiac disease. Blood tests can measure them. However, the blood tests only work on people who are eating a diet that contains gluten.
The tests are:
Anti-tissue transglutaminase antibodies (tTG): The test for these is usually very accurate.
Anti-endomysial antibodies (EMA): This blood test is also very accurate. However, it may not detect mild forms of celiac disease.
Anti-gliadin antibodies (AGA): This test does not work well for adults. It works better with very young children. Doctors sometimes use it when the results of other bloods tests are not clear.
2. Checking the Intestine for Damage
Blood tests are a good first step. If they suggest that you could have celiac disease, the next step is to check your small intestine. This involves endoscopy and a biopsy. It usually takes about 30 minutes. Doctors need this step to confirm the diagnosis.
However, for this procedure to work, you must have been eating foods with gluten for at least one month.
Endoscopy: To start, the doctor will give you a drug to make you relax. You also will have local anesthesia, so you won't feel anything. The doctor will insert a thin, soft tube in your mouth. It will go down your throat, through your stomach and into your small intestine. It has a tiny camera on the end. This lets the doctor take a good look at what is happening in your digestive tract.
Biopsy. During endoscopy, the doctor will remove small pieces of tissue from your small intestine. The doctor will send the samples to a lab. There, an expert will examine the tissue under a microscope to see if there is any damage caused by inflammation or other intestinal conditions.
3. Looking for Other Clues to Celiac Disease
Doctors may consider other factors when diagnosing celiac disease. These include genetics and dermatitis herpetiformis.
Celiac disease is passed down from one generation to the next. In fact, if you have celiac disease, your close family members may have it, too.
Nearly everyone with celiac disease has at least one of two genes related to the condition. They're known as HLA‐DQ2 or HLA‐DQ8. Doctors can use a blood test, saliva test, or a cheek swab to see if you carry either of these genes.
However, the genes are common. Many people have them, but not all of these people have celiac disease. What genetic screening can do is help your doctor rule out celiac disease when other tests do not provide clear results. In other words, if you don't have either of these genes, there's a very good chance you don't celiac disease.
If you have this type of rash and your blood tests suggest celiac disease, your doctor may do a skin biopsy to confirm that you have the disease. This would replace the intestinal biopsy.
The doctor would remove a small piece of skin near the rash. The doctor would then send the skin sample to a lab for testing. If the lab confirms that you have dermatitis herpetiformis and your blood tests are positive for celiac disease, your doctor can confirm the diagnosis.
Celiac Disease Versus Gluten Sensitivity
Some people have trouble with gluten even though they don't have celiac disease. That's called gluten sensitivity.
When they eat food with gluten, they might have the same kind of symptoms as people with celiac disease. But, when they stop eating these foods, their symptoms go away. They don't have intestinal damage. Eating gluten does not cause their immune system to make extra antibodies. And, if they have blood tests or biopsies, people who are sensitive to gluten will not test positive for celiac disease.
The only way for doctors to diagnose gluten sensitivity is to test for celiac disease. If you test negative, the doctor would ask you to eat no gluten for a set amount of time. If your symptoms go away, the doctor can diagnose you as having gluten sensitivity.