Tests
Most testing is performed to diagnose celiac disease in symptomatic patients. Although general screening is not currently recommended, tests may be ordered on the asymptomatic close relatives of patients with celiac disease and may sometimes be ordered on patients with associated conditions when the doctor feels that the patient is at an increased risk for celiac disease.
In the past, the only way to diagnose celiac disease was by examination of a biopsy of the small intestine. While this microscopic evaluation is still considered the gold standard and is used to confirm a diagnosis of celiac disease, the availability of less invasive blood tests has reduced the number of biopsies needed.
The best initial laboratory test for diagnosis of celiac disease is anti-tissue transglutaminase antibody (anti-tTG), IgA. If this test is positive, it is likely that the patient has celiac disease. If the Anti-tTG is negative but the physician still suspects celiac disease, he may order other tests discussed on the celiac disease tests page. In either case, the doctor may request an intestinal biopsy to determine whether there is damage to the intestinal villi.
Other tests may be ordered to evaluate the severity of the disease and the extent of a patient’s malnutrition, malabsorption, and organ involvement. These may include a:
One or more of the celiac disease blood tests may be ordered after a patient has been on a gluten-free diet for a period of time. This is done to verify that antibody levels have decreased, which suggests that the diet has been effective. If the patient’s symptoms have not subsided, celiac disease tests may be done to check for dietary compliance and to help the doctor and patient look for either hidden gluten in their diet or for other reasons for their unrelieved symptoms.
Genetic tests that look for the markers that are strongly associated with celiac disease have recently become available. These tests look for the Human Leukocyte Antigen (HLA) markers DQ2 and DQ8. A positive result does not diagnose celiac disease since about 30% of the general population also carry these markers but do not have the disease. A positive result requires confirmation. However, a negative result rules out celiac disease. These tests are most useful for family members of individuals with the disease who fall into a high risk category and for those with other diagnostic test results that are inconclusive.
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