SIGNIFICANCE OF GLIADIN ANTIBODIES IN CELIAC-DISEASE (CD)

Gliadin antibodies (IgA and IgG) have been determined by enzyme immunoassay (EIA) in our laboratory since 1987. 25 AU (arbitrary units) is recommended as the upper limit of the normal range. Here we report the results of the determinations of gliadin IgA antibodies in 70 patients suspected of having coeliac disease (CD), who underwent a small bowel biopsy for the first time. In 15 untreated patients with proven CD gliadin IgA antibodies ranged from 105 to 765 AU (median = 232 AU), in contrast to the findings in 55 patients with other gastrointestinal diseases (range from 0 to 175 AU, median = 9 AU; p < 0.0001). The calculated sensitivity was 100% and the specificity reached 62% using 25 AU as a cut off. The recommendation of a higher cut off (50 AU) to achieve a higher specificity (82%) with equal sensitivity is discussed using the ROC curves and the Youden Index. Gliadin IgG antibodies were simultaneously determined in 29 out of the 70 patients. Taking 25 AU as a cut off the sensitivity was also 100% but the specificity was lower (29%) in comparison with gliadin IgA antibody testing. The determination of gliadin IgA antibodies by a standardized EIA is a highly sensitive diagnostic tool for screening candidates for small bowel biopsy suspected of having CD. The number of jejunal biopsies can be greatly reduced by using this test. It can also be used for monitoring patients under gluten-free diet or gluten challenge.