June 15, 2022

Testing and diagnosis for celiac disease

by

Diagnosis for this autoimmune disorder requires a two-step testing process.

Celiac disease is an autoimmune disorder in which gluten damages the small intestine. Gluten is a protein present in wheat, rye and barley. In people who have celiac disease, gluten causes an immune system reaction that can lead to uncomfortable digestive problems, nutrient absorption issues and other symptoms. About 1 percent of people globally have the condition. If you suspect you have celiac, you can undergo celiac disease testing.

“For adult patients, a diagnosis requires a positive blood test for celiac antibodies and a biopsy of the small intestine that shows certain histological features that are consistent with celiac disease,” said Dr. Dawn Adams, a gastroenterologist, director of the Vanderbilt Celiac Clinic and medical director of the Vanderbilt Center for Human Nutrition.

Before celiac disease diagnosis

Before being tested for the disorder, you should not change to a gluten-free diet to see if your symptoms go away. “The blood test and the biopsy depend on having been exposed to gluten,” Adams explained. “So if someone is already gluten-free, a negative test doesn’t rule out celiac disease.” That’s because the test would not be able to detect celiac antibodies.

If you have already been eating gluten free, you’ll need to do a gluten challenge to reintroduce gluten to your diet for about six weeks for accurate testing.

Celiac disease testing process

Usually someone undergoes the blood test first, followed by the biopsy if they receive a positive result. Your primary care doctor can order the test, which involves a routine blood draw. However, in some instances patients may end up having the biopsy beforehand.

The biopsy is taken during an endoscopy. The procedure involves inserting a small lighted camera into your mouth while you’re under general anesthesia. The camera views the esophagus and small intestine. For an endoscopy, you do not need to do any bowel prep. Adams said the only major requirement prior to the procedure is not eating for six hours. Afterward, you will likely need to rest because of having been under anesthesia, but other than a day of grogginess, you won’t have a recovery period.

The importance of both celiac disease tests

“If the blood test is positive,” Adams said, “you should not go gluten free. You should get a biopsy scheduled ASAP so you can confirm the results.” Gastroenterology guidelines requires both the biopsy and blood test to diagnose adults. “There are some instances where blood tests are borderline positive or mildly positive,” Adams added, “and the patient doesn’t actually have celiac disease.”

A positive blood test but a negative biopsy could indicate a different autoimmune disease and warrant further testing, Adams explained. And in some cases, children will have a positive blood test at young age but then test negative a few years later, despite not having been on a gluten-free diet.

“We don’t know why people sometimes have short spikes in these serologies,” Adams said, “but it does not confirm celiac disease. So you need to have the biopsy, too.”

There is a caveat for children, however. “If you have a blood test that is 10 times the upper limit of normal on two separate occasions,” Adams explained, “then you can diagnose celiac disease without a biopsy.”

The importance of getting a diagnosis for celiac

Celiac disease has a 10% chance of being passed down to a child. “So children, siblings and parents all need to be screened if they’re related to someone with celiac disease, “Adams added.

Diagnosing celiac disease is crucial because when left untreated celiac disease can lead to long-term health effects, like other autoimmune disorders and nutrient deficiencies. Treatment currently involves adopting a gluten-free diet. But Adams stressed that people shouldn’t go gluten free unless medically necessary and under the guidance of their healthcare provider. A gluten-free diet, if not done carefully and strategically, can also lead to nutrient deficiencies.

gluten-free diet

Need help?

If you think you may have celiac disease or a gluten intolerance, the Vanderbilt Celiac Disease Clinic may be able to help. The clinic sees patients with new, existing or difficult diagnoses of celiac disease. The clinic is also active in clinical trials of medications that could treat this condition.

Learn More