Celiac Disease Diagnosis & Tests

Who should undergo antibody blood tests for celiac disease?

Some experts recommend that antibody blood tests be used to screen healthy persons with no signs or symptoms for celiac disease. In Italy, where celiac disease is common, all children are screened for celiac disease. Experts in the United States do not recommend screening healthy persons for celiac disease. Antibody blood tests are only recommended for individuals with a higher likelihood than normal of having celiac disease. These patients are:

1. Patients with chronic diarrhea (diarrhea that does not resolve in three weeks), increased amount of fat in the stool (steatorrhea), and weight loss
2. Patients with excess gas, bloating, and abdominal distension
3. First and second degree relatives of patients who have celiac disease
4. Children with growth retardation
5. Patients with unexplained iron deficiency anemia
6. Patients with skin rashes suggestive of dermatitis herpetiformis
7. Patients with recurrent painful mouth sores (aphthous stomatitis)

Patients with disease known to be associated with celiac disease. Examples of these diseases include insulin-dependent diabetes mellitus, autoimmune thyroid disease, rheumatoid arthritis, systemic lupus, ulcerative colitis, etc.

Why is it important to accurately diagnose celiac disease?

Diagnosis of celiac disease should be firmly established before commencing treatment with a gluten free diet for several reasons.

1. The gluten free diet is a life-long and tedious commitment that should not be taken lightly. It is more costly than a normal diet and has significant social implications for dining out.
2. Patients with irritable bowel syndrome (IBS) may experience improvements in bloating, abdominal pain, and diarrhea with a gluten free diet. These patients may be misdiagnosed as having celiac disease. Without confirmation of celiac disease by small intestinal biopsy, they may be unnecessarily committed to life-long gluten restriction.
3. A gluten free diet can lower blood antibody levels and allow the microscopic appearance of the small intestine to lose the typical appearance of celiac disease, complicating subsequent efforts at making a firm diagnosis of celiac disease.

How are malabsorption and malnutrition evaluated in celiac disease?

Celiac disease causes malabsorption of nutrients and leads to malnutrition. Tests are available that help in the evaluation of malabsorption and malnutrition; however, because other diseases can cause both malabsorption and malnutrition, these tests cannot be used to diagnose celiac disease.

Stool examination for malabsorption

Fat in a sample of stool placed on a glass slide can be stained with a dye (Sudan stain) to make the fat visible under the microscope as globules. Stool from patients with celiac disease often contains many stained globules of fat, and Sudan staining is a quick and easy screening test for increased amounts of fat in the stool (steatorrhea). To conclusively diagnose steatorrhea, however, stool is collected over a 72-hour period, and the fat in the stool is chemically measured and quantified. Steatorrheic stools have abnormally high quantities of fat. Since malabsorption and steatorrhea can occur with other intestinal diseases (such as small intestinal bacteria overgrowth, prior small intestinal resection, extensive Crohn's disease of the small intestine, and chronic pancreatitis), stools with large amounts of fat only raise the suspicion of celiac disease but cannot be used to diagnose celiac disease.