Comparative Evaluation of Serologic Tests for Celiac Disease Diagnosis and Follow-Up

Abstract

Anti-endomysium antibody (EmA) testing is used in the diagnosis of celiac disease (CD). The identification (1) of tissue transglutaminase (tTG) as the main antigen of EmA led to the development of commercial ELISAs for serum anti-tTG detection. At first, a guinea pig antigen (2)(3)(4)(5)(6)(7) yielded both sensitivity and specificity lower than those of EmA; therefore, human recombinant tTG (8)(9)(10)(11) was introduced to improve diagnostic accuracy and to overcome problems such as species specificity and cross-reactivity to contaminant proteins. However, the standardization of assays (12), the choice of cutoff value, the clinical relevance of these autoantibodies (13)(14), and the diagnostic accuracy of different commercial tests remain unresolved (15)(16)(17)(18). This study aimed to assess the diagnostic accuracy of five commercially available IgA anti-tTG ELISA reagent sets (four using a human recombinant and one a guinea-pig tTG antigen) for pathologically confirmed CD and to evaluate the changes in anti-tTG autoantibody concentrations during treatment of CD with a gluten-free diet (GFD). This prospective study included 101 consecutive untreated adults (79 women and 22 men; median age, 37 years; range, 21–72 years) referred to University gastroenterologic outpatient clinic between January 2000 and May 2001 in whom CD was subsequently diagnosed by means of the typical appearance of small intestinal mucosa (19) (Marsh grade III in 95 patients and grade II in 6 patients) and by a positive clinical response to a GFD. We reported on 34 of these patients (all EmA-positive) previously (17). A duodenal biopsy was performed in all patients on the basis of clinical history and serologic assessment, including EmA testing and nutritional indexes. In all patients, a follow-up biopsy and serologic monitoring were repeated at 1 year ± …