By Van Waffle
Several tests are used in diagnosing celiac disease. Certain classic symptoms such as diarrhea and weight loss are present in many, but not all, cases. A genetic test can determine whether a person is predisposed to the condition. A blood test measures whether the patient’s immune system is producing certain antibodies highly suggestive of celiac disease. But a duodenal biopsy remains what many doctors consider the gold standard in diagnosis.
A biopsy involves collecting several tissue samples from the patient’s duodenum, the upper part of the small intestine. Ideally more than four samples should be taken, because damage can be patchy. The test investigates several aspects of the structure of the gut lining. In particular it looks at the villi, tiny finger-like projections that cover the inside of the gut, to see whether they have become flattened.
This damage, called villous atrophy, is characteristic of celiac disease and helps distinguish it from other similar conditions like non-celiac gluten sensitivity. This observation is critical because celiac disease can have specific long-term health implications such as decreased bone density not caused by other illnesses.
However, once a person with celiac disease switches to a gluten-free diet, the diagnostic tests will not work. The antibodies for gluten disappear from the blood and the villi in the gut may partially or fully heal. This can happen even if not all sources of gluten have been eliminated. Hidden celiac disease can continue to cause damage such as decreased bone density without obvious symptoms.
For this reason it is important to rule out celiac disease before switching to a gluten-free diet. Initial screening may include genetic and antibody tests. Some researchers argue that extremely high antibody results may justify diagnosis with a biopsy. However, in the vast majority of cases, duodenal biopsy remains essential in identifying celiac disease.