Diagnostic accuracy of IgA anti-tissue transglutaminase in patients suspected of having coeliac disease in Iran.

Background And Aim: As there are little data about the sensitivity of the IgA anti-tissue transglutaminase (IgA anti-tTG) antibody test in the clinical practice setting, we evaluated the sensitivity of this serologic test in a group of patients who were suspected of having coeliac disease and had serologic testing performed at commercial laboratories.

Patients And Methods: The study was performed at Poursina Hakim Research Institute in Isfahan-Iran. A total number of 350 consecutive patients were enrolled in our study. They were divided into 3 groups: classical mode of presentation, atypical mode of presentation and patients with non specific prolonged gastrointestinal symptoms. Upper gastrointestinal endoscopy, histopathologic examination of biopsies from the second part of duodenum and serologic evaluation were performed for every patient. Biopsy specimens were evaluated according to Marsh (1992, revised in 1997).

Results: The overall sensitivity and specificity of IgA anti-tTG antibody were 38% and 98%. The positive and negative predictive values for the anti-tTG antibodies were 57% and 96%, respectively. The sensitivity was 80% in patients with Marsh IIIC.

Conclusion: In contrast to other reports suggesting a diagnostic accuracy of more than 90% for anti-tTG antibody in coeliac disease patients, our data showed that we are still far from an ideal screening serologic tool which can rely on the antibody test as the sole way of identifying patients with coeliac disease. This could result in many missed diagnoses, in particular in patients with lesser degrees of Marsh classification.