Many people don’t know they have celiac disease. Researchers think as few as 1 in 5 people with the disease ever find out that they have it.
Damage to the intestine happens slowly, and the symptoms can vary a lot from person to person. So it can take years to get the diagnosis.
Diagnosis: What to Expect
Since celiac disease tends to run in families, if you have a parent, child, brother, or sister with the disease, talk to your doctor about whether you should be tested. Celiac disease is more common in people with type 1 diabetes, autoimmune liver disease, thyroid disease, Down syndrome, Turner syndrome, or Williams syndrome. So if you have any of these conditions, you should also ask your doctor to test you for celiac.
Gluten Needed Before Tests
If you’re on a gluten-free diet, your doctor may put you on a "gluten challenge" plan before you take these tests. You’ll eat at least two servings of gluten (four slices of wheat-based bread) every day for 8 weeks.
Blood and Genetic Tests
To find out if you have celiac disease, you may first get:
HLA genetic test. This looks for the HLA-DQ2 and HLA-DQ8 genes. If you don’t have them, it’s very unlikely that you have celiac disease. You may get a blood test, saliva test, or a swab of the inside of your cheek.
These tests aren’t enough to show that you have celiac disease. But if the results show that you might, or it seems very likely you might have celiac disease, your next step is endoscopy.
This procedure lets your doctor check your small intestine for damage. They’ll insert a scope with a camera through your mouth, down your esophagus, and into your intestinal tract. Your doctor will likely take a little bit of tissue from the lining of your small intestine for further study. Doctors call this a biopsy.
In particular, your doctor will check tiny, fingerlike projections called villi on the lining of the small intestine. Damaged villi are a sign of celiac disease.
Endoscopy takes about 15 minutes and you can get it done in a doctor’s office. To find out if you have celiac disease, you must still be on a diet containing gluten when you get the endoscopy.
Your biopsy may show that you have celiac disease. If your biopsy shows that you don’t have celiac disease, but your doctor still thinks gluten is the cause of your symptoms, you might have
“non-celiac gluten sensitivity.” That means that your body doesn’t handle gluten well, even though you don't have celiac disease.