The diagnosis of celiac disease is often delayed and it may take several months or years for the patient and the health care professional to think of it as the cause of many non-specific symptoms. History and physical examination may give direction as to the diagnosis, but commonly it take many visits with the patient complaining of recurrent abdominal pain, non-specific joint aches, or demonstrating chronic anemia that does not respond to iron treatment, to raise the suspicion that celiac disease is a possibility. When the diagnosis is suspected, there is a two-step screening process to make the diagnosis:
Blood test for immunoglobulin A anti-tissue transglutaminase antibody (IgA TTG). Testing for antiendomysial antibody may also be considered.
If the screening blood test is positive, then endoscopy and biopsy of the lining of the duodenum (the first part of the small intestine) is recommended. Usually performed under sedation, a fiberoptic tube is passed through the mouth, through the esophagus and stomach into the duodenum and a small bit of tissue is taken to be examined under a microscope.
It is important that the patient eats a regular diet for many weeks before the testing procedures. If the patient has already started a gluten free diet, it may cause the tests to be falsely negative. Once the diagnosis is made, screening for osteoporosis may be appropriate. Since it is often familial, once one person in the family is diagnosed with celiac disease, it is reasonable to have other close family members screened.