Diagnosis

Many people with celiac disease don't know they have it. Two blood tests can help diagnose it:

• Serology testing looks for antibodies in your blood. Elevated levels of certain antibody proteins indicate an immune reaction to gluten.
• Genetic testing for human leukocyte antigens (HLA-DQ2 and HLA-DQ8) can be used to rule out celiac disease.

It's important to be tested for celiac disease before trying a gluten-free diet. Eliminating gluten from your diet might make the results of blood tests appear normal.

If the results of these tests indicate celiac disease, your doctor will likely order one of the following tests:

• Endoscopy. This test uses a long tube with a tiny camera that's put into your mouth and passed down your throat (upper endoscopy). The camera enables your doctor to view your small intestine and take a small tissue sample (biopsy) to analyze for damage to the villi.
• Capsule endoscopy. This test uses a tiny wireless camera to take pictures of your entire small intestine. The camera sits inside a vitamin-sized capsule, which you swallow. As the capsule travels through your digestive tract, the camera takes thousands of pictures that are transmitted to a recorder.

If your doctor suspects you have dermatitis herpetiformis, he or she might take a small sample of skin tissue to examine under a microscope (skin biopsy).