Abstract
In the diagnostic work up of a patient suspected of having inflammatory bowel disease (IBD), biomarkers are helpful in prioritizing further examinations, including endoscopy, and/or in the decision to start or intensify treatment. C-reactive protein has many advantages, but its short half-life makes this a particularly good marker in the detection and follow up of disease activity in Crohn's disease. In contrast, ulcerative colitis (with the exception of severe colitis) has only a modest-to-absent C-reactive protein response despite active inflammation. As stools are easy accessible in IBD patients, fecal markers hold a specific promise and recent studies even claim superiority of fecal markers over serum markers. A number of neutrophil-derived proteins shedding in stools have been studied. Calprotectin and lactoferrin are probably the most promising given their abundance in granulocytes and their stability and resistance to degradation. Although calprotectin and lactoferrin are very sensitive markers to detect inflammation in the gastrointestinal tract, they are not specific for IBD and increased levels are also found in neoplasia, NSAID abuse, infections and polyps. In children with abdominal symptoms and diarrhea, a positive test for calprotectin or lactoferrin may prioritize endoscopy. The antimicrobial and antiglycan antibodies detected in many IBD patients have no place in the diagnostic work up, except in cases of colitis-type unclassified, in which anti-Saccharomyces cerevisiae and perinuclear antineutrophil cytoplasmic antibodies still have the best accuracy. Nevertheless, these markers are often negative in this setting. The interest in antimicrobial and antiglycan antibodies has recently been increased as they have shown to act as surrogate markers of complicated aggressive disease.