Understanding symptoms and signs in inflammatory bowel disease

The natural history of Crohn's disease (CD) and ulcerative colitis (UC) is highly variable, but most typically follows a course of relapses and remissions. Some patients have chronically active disease with no or few apparent remissions. In some, the condition appears to 'burn out', and they enter long term remission. Series from specialized centers may tend to over-estimate clinical severity [1]. Generally, symptoms of UC tend to be uniform; most patients complain of abrupt onset passage of blood, diarrhea and weight loss. Each acute relapse typically has similar clinical features. Because of its greater anatomical distribution potentially involving any part of the gastrointestinal tract, its transmural distribution and its propensity to give raise to complications such as strictures and fistulae, CD shows greater variability between patients in clinical features. Also, as the disease evolves involving different parts of the gastrointestinal tract, the clinical features in any one patient may also change through time. Symptoms and signs of inflammatory bowel disease (IBD) ultimately depend on the extent, distribution and severity of the gastrointestinal inflammation. Many of the clinical features of CD and UC are related to the anatomical location of disease. Abdominal colic is caused by intestinal strictures and diarrhea by intestinal inflammation. Other features such as anorexia, weight loss and malnutrition, anemia and constitutional features are largely due to the systemic consequences of intestinal inflammation. In recent years, the role of soluble mediators of intestinal inflammation in the pathogenesis of non-intestinal features of IBD has been appreciated. Cytokines are produced by many different tissues in response to immune stimulation and mediate a multiplicity of immunologic and nonimmunologic functions [2, 3]. As well as local (autocrine- paracrine) actions, cytokines have systemic (endocrine) effects, many mediated by the central nervous system [4, 5]. While the short-term, local effects of cytokines may be beneficial to the organism in the acute phase of an immune reaction, prolonged systemic cytokine activity as in IBD is often deleterious (Table 1) [6, 7].