Background and aims: Serological assays are desirable for the diagnosis of inflammatory bowel disease (IBD) in the paediatric age group. The aim of this study was to test the diagnostic accuracy of assays for perinuclear antineutrophil cytoplasmic antibodies (ANCA) and anti-Saccharomyces cerevisiae antibodies (ASCA) in patients with ulcerative colitis (UC) and Crohn’s disease (CD). Methods: Assessment of pANCA and ASCA was performed using the standardized indirect immunofluorescence technique and ELISA, respectively. Serum samples were obtained from 41 patients with CD (15.4 ± 3.4 years of age) and from 33 patients with UC (16.0 ± 3.9 years of age). Results: The positive pANCA test alone yielded 82% a sensitivity and 83% specificity for UC. Positive ASCA-IgA and ASCA-IgG yielded 44% sensitivity and 100% specificity for CD. The combination of negative pANCA and positive ASCA-IgA and ASCA-IgG yielded 37% sensitivity and 100% specificity for CD. Positive pANCA and negative ASCA-IgA and ASCA-IgG yielded 61% sensitivity and 95% specificity for UC. One fifth of all patients was serologically completely negative. Conclusion: ASCA and pANCA assays are highly disease specific for CD and UC, respectively. A combination of both tests may help clinicians to facilitate their clinical decision when the diagnosis of IBD is initially uncertain. The test can help in diagnosing and categorizing patients with ulcerative colitis and Crohn’s disease.

        Key words: anti-Saccharomyces cerevisiae antibodies (ASCA), antineutrophil cytoplasmic antibodies (ANCA), inflammatory bowel diseases, Crohn’s disease, ulcerative colitis, children and adolescents