Which test is crucial for diagnosing Celiac disease?

The small bowel biopsy is crucial for diagnosing Celiac disease due to its ability to provide direct evidence of the characteristic damage to the intestinal villi caused by gluten consumption. In individuals with Celiac disease, the intake of gluten leads to an autoimmune response that results in inflammation and atrophy of the small intestine's mucosa. When a biopsy is performed, the tissue sample can be examined histologically to identify the specific changes in the villi, such as flattening or blunting, that are indicative of Celiac disease.

While blood tests may initially suggest the possibility of Celiac disease by measuring specific antibodies (such as anti-tissue transglutaminase), these tests can yield false positives and do not provide the definitive diagnosis that a biopsy does. Other options like stool samples and X-rays are not appropriate or reliable for diagnosing Celiac disease. Stool tests can help assess malabsorption but do not directly indicate the presence of Celiac disease. X-rays are not relevant to the diagnosis of this condition. Therefore, the small bowel biopsy remains the gold standard for confirming a diagnosis of Celiac disease.