Role of serology and routine laboratory tests in childhood inflammatory bowel disease

Introduction: Serology is reported to be helpful in evaluating children for inflammatory bowel disease (IBD), and distinguishing chronic ulcerative colitis (CUC) from Crohn's disease (CD). The markers include perinuclear staining anti-neutrophil cytoplasmic antibody (pANCA) for CUC and anti-Saccharomyces cerevisiae antibody (ASCA) for CD. In the clinical setting, hemoglobin (Hgb) and erythrocyte sedimentation rate (ESR) are commonly performed for screening symptomatic children for IBD. We examined whether there was an additional benefit of serology in addition to specific symptoms and routine laboratory tests in screening for IBD. Method: Medical record data was reviewed on children investigated for IBD from February 1999 to April 2001. Children were included if they had blood analyzed for pANCA and ASCA, Hgb, ESR, and colonoscopy as part of their assessment. Results: Of 177 cases reviewed, 51 were diagnosed with CUC, 39 with CD, and 26 other inflammatory conditions. Visible rectal bleeding was the most discriminating symptom (occurred in 60/90 cases of IBD and 5/61 without IBD). There was a significant difference between the proportion with CUC positive for pANCA (42/51) and those with abnormal Hgb and ESR (30/51) (p < 0.05), but not between children with CD who were ASCA positive (18/39) and those with abnormal Hgb and ESR (26/39) (p = 0.27). The sensitivity and specificity of combined pANCA and ASCA was 68% and 92%, respectively. For the combination of Hgb, ESR, and the presence of rectal bleeding the respective values were 86% and 67%. Serology combined with Hgb and ESR and rectal bleeding as independent factors significantly (p < 0.05) improved sensitivity (89%) but reduced specificity (60%). Screening with the combination of rectal bleeding, Hgb, and ESR identified 86% (77/90) patients with IBD prior to an endoscopic procedure. A further 3 of 90 (3.3%) screened positive with the addition of serology. Conclusion: Serology tests have a high degree of specificity for IBD while routine laboratory test have a higher sensitivity. When serology is combined with rectal bleeding, Hgb, and ESR, the sensitivity of screening children for IBD is significantly improved. However the large majority of children with IBD can be identified with a clinical history and routine laboratory tests as needing an endoscopic procedure with little benefit of adding serology.