Physicians test for celiac disease using either a blood test or endoscopic biopsy. Doctors may decide to test for celiac disease after discussing symptoms and medical history with their patients. A blood test may show higher levels of certain antibodies, but only an endoscopic biopsy confirms the presence of celiac disease, say experts at the Celiac Disease Foundation.
Doctors may prescribe several other tests to look for nutritional deficiencies and test for the presence of fat in stools, say experts at WebMD. Abnormal results may suggest celiac disease is an underlying cause, but those symptoms are also associated with other autoimmune disorders, which necessitates an endoscopic biopsy for a precise diagnosis.
Physicians use the endoscopic biopsy test to study the complete gastrointestinal tract, or GI tract. To do so, doctors insert a tube down the esophagus. The tube then moves through the stomach and small intestines. Doctors watch the procedure on a screen and can remove small portions of tissue in the GI organs if necessary.
After the test, doctors use a Marsh scale to identify or deny the presence of celiac disease. Stage 0 shows normal function, while Stages I through IV show abnormalities, such as increased lymphocytes and enlarged crypts. Most patients with celiac disease classify as a Stage III on the Marsh scale.