Several diagnostic methods are available when gluten intolerance (celiac disease) is suspected. Usually a diagnosis is sought when the symptoms of malabsorption and malnutrition have been observed. There are two major tests available to physicians for the diagnosis of gluten intolerance:

• Biopsy of the small intestine. This is considered the best test for diagnosing gluten intolerance because of its high degree of accuracy. The test involves a physician obtaining a sample of the intestinal lining through a procedure known as an esophagogastroduodenoscopy (EGD). The EGD procedure, a type of upper endoscopy, uses a small camera, inserted down the throat on a flexible tube, to navigate down to the intestinal lining and remove a small sample. The patient typically receives general anesthesia or a sedative. A pathologist will then examine the sample to check for characteristics that indicate gluten intolerance, such as a loss of villi (protrusions found on the lining of the small intestine that absorb nutrients into the bloodstream).
  
  
• Antibody test. A blood test for the presence of certain antibodies – specifically, antibodies to endomysium (bands of connective tissue spread among muscular fibers) and transglutaminase (a substance that repairs injured or inflamed tissue). These antibodies form when the immune system reacts to the presence of substances it views as threatening. When certain specific antibodies are present in the bloodstream, an individual has a greater than 95 percent chance of having gluten intolerance.

Though not able to diagnose gluten intolerance directly, there are also several types of blood tests available for detecting the related malnutrition and vitamin deficiencies. These tests will usually show some type of a reduction in blood protein levels or iron-deficiency anemia in gluten-intolerant individuals.

Because gluten intolerance is a hereditary disease, the family members of an individual who has gluten intolerance may wish to be tested for the disease.

Because of recent research that has shown a close relationship between gluten intolerance and the development of osteoporosis, some physicians are screening patients diagnosed with osteoporosis for gluten intolerance as well. And people who are diagnosed with gluten intolerance may be screened for osteoporosis with a bone density test such as a DEXA scan, a type of x-ray.