Adult population screening for coeliac disease: comparison of tissue-transglutaminase antibody and anti-endomysial antibody tests

Serological assays are very helpful in the diagnosis of coeliac disease. The anti-endomysial antibody test has a specificity of almost 100%, whereas the specificity of the anti-tissue transglutaminase antibody test is lower, circa 95%. Moderate increases in anti-tissue transglutaminase antibodies may be found in other medical disorders, besides coeliac disease. Increased numbers of intra-epithelial lymphocytes are found not only in coeliac disease but also in other medical conditions. Reliable evidence that a patient has coeliac disease can only be based on the presence of anti-endomysial antibodies or demonstration that the histological lesion is gluten sensitive. Serological screening tests for coeliac disease have significantly advanced the diagnosis of this condition. The very high specificity (almost 100%) of anti-endomysial antibody detection has been repeatedly confirmed, whereas a lower specificity (90–95%) is found with anti-tissue transglutaminase antibody assays. In the study by Malekzadeh and colleagues, a group of study participants were identified with raised anti-tissue transglutaminase antibodies, but the endomysial antibody test was negative in 86%. Although many of these participants were found to have raised intra-epithelial lymphocytes in their small intestinal mucosa, there is currently insufficient evidence to confidently diagnose gluten-sensitive disease in these patients. Hence, their report that a minimum prevalence of 1:104 of gluten sensitivity is found in the general population of Iran is likely to be an over-estimate and requires confirmation.