Ulcerative colitis

Inflammatory bowel disease (IBD) is a group of inflammatory conditions of the colon and the intestine. The two most prominent IBD conditions are Crohn’s disease and Ulcerative colitis. Although similar in symptoms, they are very different conditions where the main difference is the location and nature of the inflammatory changes. Furthermore, IBD should be distinguished from Irritable bowel syndrome (IBS), or spastic colon. IBS is a functional bowel disorder characterized by chronic abdominal pain, discomfort and bloating. IBS is often regarded as a syndrome or collection of symptoms rather than a disease. Due to the entirely different pathology, diagnostic differentiation between IBD and IBS is clinically of utmost importance.

Ulcerative colitis is a disease of the intestine, specifically affecting the large intestine or colon, giving characteristic ulcers, or open sores, in the colon. The main symptom of active disease is diarrhea mixed with blood, of gradual onset. Ulcerative colitis is associated with a general inflammatory process that affects many parts of the body. Sometimes these associated extra-intestinal symptoms are the initial signs of the disease, such as painful, arthritic knees. The disease is classified by the extent of involvement, depending on how far up the colon the disease extends, but can also be classified by the severity of their disease.

Ulcerative colitis has similarities to Crohn's disease, another form of IBD. In contrast to Crohn's disease, which can affect areas of the gastrointestinal tract outside of the colon, Ulcerative colitis usually involves the rectum and is confined to the colon, with occasional involvement of the ileum. Ulcerative colitis is an intermittent disease, with periods of exacerbated symptoms, and periods that are relatively symptom-free. The incidence of Ulcerative colitis in North America is 10–12 cases per 100,000 per year. The geographic distribution of ulcerative colitis and Crohn's disease is similar worldwide. In contrast to Crohn’s, surgery may actually be curative for UC.

Diagnosis of Ulcerative colitis

The diagnosis of Ulcerative colitis can sometimes be challenging, and a number of tests are often required to assist the physician in making the diagnosis. The diagnostic tools include endoscopy/biopsy, radiology, nuclear scan and serology. It is important to be able to make a differential diagnosis between ulcerative colitis and Crohn’s as the two diseases have different prognosis and treatment strategies.

Serological tools have been developed over the last few years. A key marker of intestinal inflammation is calprotectin, a 36 kDa zinc-binding protein. Calprotectin is very abundant in neutrophil granulocytes protein where it constitutes more than 60% of total proteins in the cytosol.

Measurement of faecal calprotectin is useful as a noninvasive screening tool to differentiate functional from organic bowel pathology. A normal value of faecal calprotectin supports a clinical suspicion of irritable bowel syndrome. In Ulcerative colitis and Crohns disease faecal calprotectin correlates closely with disease activity and normalization of faecal calprotectin is a predictor of mucosal healing. Further, faecal calprotectin is a predictor of relapse in patients with inflammatory bowel disease. Slightly or moderately elevated values of calprotectin can be difficult to interpret and should be judged along with the patients’ clinical presentation. Other tests adjunct to calprotectin may be used in the diagnosis of IBD, such as antibodies against Sacharomyces cereviciae (ASCA) and pANCA. ASCA seems to be more associated with Crohn’s disease and pANCA is more prevalent in Ulcerative colitis. Other ANCA reactivity may be seen in association with IBD. 

Relevant Literature

  1. Ford AC et al. Efficacy of biological therapies in inflammatory bowel disease: systematic review and meta-analysis. Am J Gastroenterol. 2011;106:644-59
  2. Jang ES et al. Age as a clinical predictor of relapse after induction therapy in ulcerative colitis. Hepatogastroenterology 2009;56:1304-9
  3. Kaufman SS et al. Gastroenteric inflammation in children with ulcerative colitis. Am J Gastroenterol. 1997;92:1209-12
  4. Peeters M et al. Diagnostic value of anti-Saccharomyces cerevisiae and antineutrophil cytoplasmic autoantibodies in inflammatory bowel disease. Am J Gastroenterol. 2001;96:730-4
  5. Xavier RJ, Podolsky DK. Unravelling the pathogenesis of inflammatory bowel disease. Nature 2007;448:427-34