Serumanti-Gliadin IgA Antibody (AAG-IgA) and D-Xylose Absorption Test for Differential Diagnosis of Celiac Disease (CD) and Food Hypersensitivity (FH)

Abstract

Clinical features of CD may overlay the presentation of other diseases responsible for small intestinal anatomical and/or functional changes. Among these, FH is an important cause of chronic diarrhea in children with identical age-range of common CD presentation. The aim of this study was to evaluate the AAG-IgA and D-xylose absorption tests for differential diagnosis of CD and FH. We studied 10 patients, mean age 2.7 ± 1.6 years with CD (jejunal biopsy: total villous atrophy with hyperplasia of the crypts) and 14 patients, mean age 2.1 ± 0.9 years, with FH(jejunal biopsy: mild/moderate villous atrophy). IgA deficiency was ruled out. Serum AAG-IgA was measured by enzyme immunoassay (ELISA) (Gluten-IgA EIA, Pharmacia Diagnostics AB), abnormal levels: >30.3, expressed in Arbitrary Units, AU. D-xylose absorption test was performed using 0.5g/Kg followed by a 1 h and 2 h blood level determinations, normal values: >=30 mg/%. AAG-IgA values were higher in DC(240.4±136.2 AU) than in FH (19.3±8.5 AU) (p<0.001, Mann-Whitney test). On the contrary, D-xylose values were lower in CD(13.2±8.0 mg/%) than in FH (41.3±11.8 MG/%) (p<0.001). The combined use of both tests, AAG-IgA determination and D-xylose absorption test, showed sensitivity of 100% and specificity of 86% in diagnosis CD. Jejunasl biospsy was performed only in 2 out of 14 children with FH because AAG-IgA or D-xylose test was found abnormal. We concluded: 1) The determination of serum AAG-IgA and D-xylose absorption test are important methods for differencial diagnosis in patients with chronic diarrhea; 2) The combined use of the above two tests is reliable for screening patients for small intestinal biopsy.