Q. How accurate are the blood tests for celiac disease?
A. The commonly used antibody tests (IgA anti-gliadin and anti-tissue trans glutaminase) can diagnose aobut 85-90% of those with celiac disease. A total IgA (immunoglobulin A) level must be done, because 10% of celiacs are deficient in this immunoglobulin, and these antibodies may be falsely low in this setting. On occasion, even those with biopsy-proven disease may test negative, so it is recommended that genetic testing for HLA-DQ2 and HLA-DQ8 genes be done. Either one or both are positive in 95-98% of celiacs, but are also present in about 25-30% of the population at large, so an intestinal biopsy remains the gold standard for diagnosis.
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