Researchers estimate that only 20 percent of people with celiac disease may receive a diagnosis. Doctors may order two blood tests to help diagnose celiac disease. If the results of these tests indicate celiac disease, your doctor may order an endoscopy to view your small intestine and to take a small tissue sample (biopsy) to analyze for damage to the villi. It's important to be tested for celiac disease before trying a gluten-free diet. Eliminating gluten from your diet may change the results of blood tests and biopsy so that they appear to be normal.
• 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.
• The endoscopic biopsy; If antibody tests and symptoms suggest celiac disease, the physician needs to establish the diagnosis by obtaining tiny pieces of tissue from the upper small intestine to check for damage to the villi. This is done in a procedure called a biopsy. The physician eases a long, thin tube called an endoscope through the mouth and stomach into the small intestine, and then takes samples of the tissue using small instruments passed through the endoscope. Biopsy remains the most accurate way to diagnose celiac disease. This procedure is always performed by a gastroenterologist, and is conducted most often in an outpatient surgical suite. The procedure lasts less than half an hour, and sedation and local anesthesia are generally used. The procedure involves a long, thin tube with a small camera on the end. The physician will insert the tube into the patient's mouth, down the throat, and into the esophagus. When the tube reaches the patient's stomach, the physician fi nds the entryway into the small intestine (the duodenum) and inserts the tube there. As the tube is making its way to the small intestine, the camera on the end sends a video image to a monitor in the procedure room. On the monitor the physician can visually assess any evident abnormalities such as ulcers or gastritis. In the small intestine, the physician examines most of the duodenum, the area affected by celiac disease. However, in many celiac patients, their duodenum appears normal at the time of biopsy. This is why the surgical removal of tissue is so important, it is only under a microscope that a definitive diagnosis of celiac disease can be made. To take some tissue for biopsy, the physician inserts a tiny surgical instrument through the endoscope tube. Working in concert with a surgical nurse, the physician will take 5 to 6 biopsies. Each one is taken by grasping sections of the small intestine and slicing them gently away from the walls of the intestine. Multiple tissue samples are vital to make an accurate diagnosis, celiac disease can cause patchy lesions in the duodenum, which can be missed if only one or two samples are taken. Results of the biopsy will confirm if a patient has celiac disease. There are no nerve endings in the lining of the intestine, so this procedure does not cause any pain. Afterward, some patients experience a sore throat, but most have no memory of the procedure.