Diagnosing Celiac disease in adults and children can be difficult because some of its symptoms are similar to those of other diseases. Adult/Pediatric Celiac disease symptoms are similar to those of irritable bowel syndrome, Crohn's disease, ulcerative colitis, diverticulosis, intestinal infections, chronic fatigue syndrome, and depression.

Recently, researchers discovered that people with celiac disease have higher than normal levels of certain antibodies in their blood. Antibodies are produced by the immune system in response to substances that the body perceives to be threatening. To diagnose Celiac disease, physicians test blood to measure levels of antibodies to gluten. These antibodies are antigliadin, anti-endomysium, and antireticulin.

There is a blood test available (called Celiac Panel) that will screen for the possibility of Adult/Pediatric Celiac disease. If the tests and symptoms suggest Celiac disease, the physician may remove a tiny piece of tissue from the small intestine to check for damage to the villi. This is done in a procedure called a biopsy: Biopsy of the small intestine is the best way to diagnose Celiac disease in adults and children.