Exams and Tests

The likelihood of celiac sprue determines the approach to diagnosis. If a low or moderate suspicion exists that celiac disease is present, a blood test for tissue transglutaminase (tTG) or antiendomysial antibody is performed. If the likelihood that someone has celiac disease is very high or the blood test result is positive, then biopsies of the small intestinal should be performed.

Genetic testing is only performed in certain circumstances.

Blood tests

Blood chemistry, red blood cell, and clotting test results suggest but do not confirm the diagnosis of celiac sprue. The same abnormalities may be seen in many other diseases. 

• Electrolyte imbalances, such as low potassium level (hypokalemia), low calcium level (hypocalcemia), and low magnesium level (hypomagnesemia), may be present.
  
  
• Sometimes, malnutrition includes a low albumin level (hypoalbuminemia), a low total protein level (hypoproteinemia), and a low cholesterol level (hypocholesterolemia).
  
  
• Anemia due to deficiency in iron, folate, or vitamin B-12 may be present.
  
  
• A low serum iron level is common.
  
  
• Malabsorption of vitamin K may cause abnormal clotting test results such as a prolonged prothrombin time.

The best diagnostic tests for celiac sprue include measurements of antibody levels to endomysium and to an enzyme called tissue transglutaminase (tTG). The 2 tests are very specific for celiac disease in persons who are untreated.

Measurements of antibodies to gliadin and reticulin (a part of the cell structure) are other diagnostic tests that are less specific for celiac disease.

Small intestinal imaging tests

Radiology tests, such as small-bowel barium studies and abdominal/pelvic CT scanning, are usually not helpful in establishing the diagnosis of celiac disease. In video capsule endoscopy, a tiny camera in a capsule films the small intestine as the camera moves through it; however, this study cannot examine the tissue microscopically. These tests should be considered in the evaluation of persons with suspected celiac sprue and those who have dramatic weight loss, severe abdominal pain, intestinal bleeding, significant decrease in albumin levels, and intestinal obstruction. These symptoms may suggest the presence of tumors or ulcers in the small intestine.

Small intestinal biopsy

The lining of the small intestine usually consists of fingerlike projections called villi. The villi contain digestive enzymes and provide the large absorptive surface of the small intestine. In celiac sprue, the villi are destroyed because of the inflammatory and autoimmune process. Once the villi are destroyed, nutrients cannot be absorbed. Biopsy samples of the small intestine show mild, moderate, or severe destruction of the villi depending on the severity of the inflammation. Biopsy samples of the small intestine are obtained by introducing a small, flexible endoscope through the mouth, the stomach, and into the small intestine while the patient is sedated.