Els van de Vijver

13 leukotriene E-4 and prostaglandine E metabolite) have also been investigated as markers of inflammation. To date, however, none of these markers has been validated for clinical use.(5) Faecal markers Before a biomarker can be safely used as a clinical triage test, its discriminatory power must be defined upon the intended patient population and in a specific clinical setting within the current diagnostic pathway. This is because the sensitivity and specificity of a test can vary according to the patient population and clinical setting.(7) Figure 1 l Roles of tests and positions in existing diagnostic pathways. Figure adapted from (7) Given that the inflammation in IBD is an intestinal process, it is logical that faecal parameters have also been suggested as being valuable for the assessment of intestinal inflammation. In practice, faecal markers have indeed become very popular for assessing the presence of inflammation in the bowel. During mucosal inflammation, various substances are actively released or passively leaked into the intestinal lumen, and they are subsequently excreted in the stool. An overview of the faecal parameters that have been evaluated is presented in Table 2 .(8, 9) General introduction