Background: In view of the high diagnostic accuracy of immunoglobulin-A-tissue transglutaminase antibodies for detecting coeliac disease, we have explored whether a small bowel biopsy is always required to establish the diagnosis.
Aim: To define the transglutaminase antibody level giving a positive predictive value for coeliac disease of 100% and to subsequently assess the proportion of new diagnoses of coeliac disease having such a result.
Methods: The Celikey kit (Phadia GmbH, Frieburg, Germany) was used to measure transglutaminase antibody levels.
Results: All patients with transglutaminase antibody levels >30 U/mL, i.e. 10 x upper limit of normal in 2002/2003 had characteristic small bowel mucosal lesions. In a subsequent audit, 58% of 112 new diagnoses of coeliac disease in 2004/2005 had levels above this cut-off value.
Conclusions: We have shown that a transglutaminase antibody level can be defined which gives a positive predictive value of 100% for coeliac disease. From published data, these observations can be extended to most second-generation transglutaminase antibody kits. Our data provide further evidence that diagnostic guidelines could be modified so that small bowel biopsy is no longer regarded as mandatory in patients with such high transglutaminase antibody levels. This will avoid an invasive procedure and lead to a more rapid diagnosis and earlier treatment for over half of the new patients with coeliac disease.