IgA Antibodies against Tissue Transglutaminase in the Diagnosis of Celiac Disease: Concordance with Intestinal Biopsy in Children and Adults

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Abstract
Celiac disease (CD), an immune enteropathy caused by gluten-containing foods in genetically susceptible individuals, is usually diagnosed during childhood, but delayed diagnosis in adulthood is not uncommon (1). One-half of cases show atypical forms of the disease, e.g., iron-deficient anemia unresponsive to iron or persistent hypertransaminasemia (2)(3)(4). Patients with CD often have high circulating concentrations of anti-endomysium antibodies (EMAs), the main disease marker (5), and anti-gliadin antibodies (AGAs), the most effective marker for children <3 years (6)(7). Tissue transglutaminase (tTG) has been identified as the autoantigen of CD (8). The first assays for tTG antibodies used antigen from guinea pigs (9)(10)(11)(12)(13)(14)(15). Assays that used recombinant human tTg (rh-tTG) improved sensitivity and specificity (16)(17)(18)(19)(20)(21), but it is not well established in prospective studies whether the clinical effectiveness of rh-tTG is similar for children and adults. The aims of this study were (a) to evaluate the potential utility of rh-tTG IgA (rh-tTGA) compared with EMAs and AGAs for CD diagnosis in children and adults; (b) to analyze the concordance between rh-tTGA and small intestine biopsy (IB); and (c) to analyze the association of hypertransaminasemia and ferropenia with untreated CD. We prospectively selected 2570 patients with clinical suspicion of CD. Most patients (73.4%) were referred by the Pediatrics Department. From this cohort of patients we analyzed consecutively all patients fulfilling the inclusion and exclusion criteria. Inclusion criteria included histologic analysis of an IB and determination of serum markers for CD; the exclusion criterion was IgA deficiency. Both the IB and the immunologic markers were analyzed blindly and independently. The patients were classified into two groups. Group I consisted of 61 patients diagnosed with …