Could a Celiac Test Show a False Negative?

Is it possible to have a false negative blood test for celiac disease?

Yes, it is possible. Endomysial antibodies and anti-tissue transglutaminase antibodies (blood tests for diagnosing celiac disease) are highly reliable In diagnosing celiac disease. An individual with abnormally elevated endomysial and anti-tissue transglutaminase antibodies has a greater than 95% chance of having celiac disease. Anti-gliadin antibodies are less reliable and have a higher rate of false positive tests.

However, I personally have taken care of patients with small bowel biopsies and symptoms of celiac disease, but whose blood tests (endomysial antibodies and anti-tissue transglutaminase antibodies) were normal, and as such, represented false negative tests.

There are two recognized reasons for false negative blood tests for celiac disease:

1. Patients with deficiency of one type of antibody, IgA (they are born that way) will have low endomysial antibodies and anti-tissue transglutaminase antibodies since they are IgA-type antibodies.
2. Patients who have self-treated themselves with a gluten-free diet for weeks to months before having these tests done can have abnormal blood tests revert to normal.