Non-invasive investigation of inflammatory bowel disease

The assessment of inflammatory activity in intestinal disease in man can be done using a variety of different techniques. These range from the use of non - invasive acute phase inflammatory markers measured in plasma such as C reactive protein ( CRP) and the erythrocyte sedimentation rate (ESR) (bot h of which give an indirect assessment of disease activity) to the direct a ssessment of disease activity by intestinal biopsy performed during endosco py in association with endoscopic scoring systems. Both radiology and endos copy are conventional for the diagnosis of inflammatory bowel disease (IBD) . However these techniques have severe limitations when it comes to assessi ng functional components of the disease such as activity and prognosis. Her e we briefly review the value of two emerging intestinal function tests. In testinal permeability, although ideally suited for diagnostic screening for small bowel Crohn's disease, appears to give reliable predictive data for imminent relapse of small bowel Crohn's disease and it can be used to asses s responses to treatment. More significantly it Is now clear that single st ool assay of neutrophil specific proteins (calprotectin, lactoferrin) give the same quantitative data an intestinal inflammation as the 4 - day faecal excretion of 111Indium labelled white cells. Faecal calprotectin is shown to be increased in over 95% of patients with IBD and correlates with clinic al disease activity. It reliably differentiates between patients with IBD a nd irritable bowel syndrome. More importantly, at a given faecal calprotect in concentration in patients with quiescent IBD, the test has a specificity and sensitivity in excess of 85% in predicting clinical relapse of disease . This suggests that relapse of IBD is closely related to the degree of int estinal inflammation and suggests that targeted treatment at an asymptomati c stage of the disease may be indicated.