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Crohn's Disease

  • Definition

    Article updated and reviewed by Christian D. Stone, M.D., Assistant Professor of Medicine, Division of Gastroenterology, Washington University in St. Louis School of Medicine on June 1, 2005.

    crohn's disease falls within the broad category of disorders called inflammatory bowel disease. It is a chronic, recurrent disease characterized by inflammation of any portion of the digestive tract from the mouth to the anus.


    About one-third of all Crohn's disease cases involve only the small bowel, especially the ileum. About half of all cases involve the small bowel and colon, and about 20 percent of all cases affect the colon alone.


    The precise cause of Crohn's disease remains unknown. Our best understanding is that Crohn’s disease results from an abnormal immune response in the intestinal tract, triggered by unknown environmental factors, in persons at risk for the disease due to their genetic makeup. There is no clear evidence that diet is involved in causing Crohn’s disease.

    The disease has a peak occurrence between the ages of 15 and 35, but it has been reported in every decade of life. It is more common in Caucasians and Jews and can affect more than one member of a family. While both viruses and bacteria can cause colitis (inflammation of the colon), little evidence suggests that infections actually lead to Crohn's disease. Cigarette smoking is strongly associated with the onset and worsening of Crohn’s disease.


    Because of the varying locations of involvement and severity of disease, Crohn’s disease may present with a variety of symptoms and signs.

    The first symptoms of Crohn's disease are often abdominal pain and diarrhea. Pain is felt in the area of the navel or on the right side. joint pain, lack of appetite, weight loss, fatigue and fever are common.

    Sometimes Crohn's disease affects the skin around the anus. A variety of sores in the anal area such as skin tags, fissures (cracks), fistulas (abnormal openings from bowel to skin surface near the anus), and abscesses may occur. Less commonly, other organ systems outside the gastrointestinal tract may be affected by Crohn’s disease. These include the eyes (iritis, uveitis), liver (PSC), skin (erythema nodosum, pyoderma gangrenosum), and kidney (kidney stones).


    There is no single test used to diagnose Crohn’s disease. Rather, diagnosis is based upon the clinical presentation combined with supportive findings on examinations that may include x-rays (e.g. abdominal CT, small bowel exam), endoscopy (e.g. colonoscopy) and histology from biopsies of the intestinal tract.


    Treatment focuses on relieving symptoms of the disease by inducing and then maintaining remission. This is accomplished by prescribing medicines that reduce the inflammation in the intestinal tract. Common drugs used to treat Crohn’s disease are aminosalicylates, steroids, antibiotics, anti-TNF agents (see Infliximab below), and immunomodulators.

    The cornerstone for inducing remission in severe Crohn's disease continues to be oral or intravenous corticosteroids such as prednisone. They also have a role in managing less severe disease and in treating small bowel involvement. They are used for short-term therapy and other medications are used to maintain remission following steroids. Steroids work by reducing inflammation throughout the body and thus long-term use is associated with many side effects like osteoporosis, diabetes, and hypertension. Promising results have been obtained with the use of budesonide (Entocort), a corticosteroid with high topical anti-inflammatory activity and low systemic activity (because of extensive hepatic metabolism). This medication, though costly, can reduce the intestinal inflammation while minimizing the side effects that would commonly be experienced with prednisone.

    Another category of drugs often used in Crohn’s disease is the topically acting 5-aminosalicylates such as mesalamine (Asacol, Pentasa), sulfasalazine (Azulfidine), and balsalazide (Colazal). These medicines are quite safe, but may require large doses. Antibiotic agents, such as metronidazole may be helpful in perianal and/or colonic Crohn’s disease. How antibiotics help Crohn’s disease is not well understood, but the benefit may be the result of altered concentrations of bacteria in the colon and small bowel.

    Immunomodulatory drugs such as azathioprine (Imuran, Azasan), 6-mercaptopurine (Purinethol), or methotrexate are often effective in maintaining remission of Crohn's disease. These medications are used long-term and require monitoring to prevent adverse effects. They work by changing the way certain inflammatory cells in the intestinal lining respond to inflammatory triggers.

    Infliximab (Remicade) is a powerful anti-inflammatory drug that blocks the action of a specific molecule called tumor necrosis factor (TNF), a key mediator of the inflammatory process in Crohn’s disease. It is indicated for perianal Crohn’s disease or intestinal disease not responding to the usual first-line medications. This drug is actually a synthetic antibody and is given as an intravenous infusion for both induction and maintenance of remission. Important side effects of this medication are infusion reactions (rash, fever) and, rarely, serious infections. Other medications known as biologicals, of which infliximab is one, are being studied and may emerge as viable therapies for Crohn’s disease in the future.

    Despite advances in the medical treatment of Crohn's disease, surgery may be necessary to remove the diseased segment of bowel. Surgery is usually reserved for those in whom medical treatment has been ineffective. Other indications for surgery may include:

    • permanent narrowing or an obstruction of the bowel
    • development of a fistula between an involved segment and the bladder, vagina or skin
    • infection in the area of the anus
    • perforation of the bowel
    • abscess (localized infection) within the abdomen

    Surgery will result in remission but does not represent a cure of the disease. Most patients will have a recurrence of Crohn’s disease after surgery and thus will require additional medical therapy.

    Despite the serious nature of the disease, treatment often permits the person with Crohn's disease to lead an active and productive life with a normal lifespan. Dietary changes have not been shown to help treat Crohn’s disease because diet does not appear to reduce the inflammation in the intestines. Because weight loss is common when Crohn’s disease is active, it is important that patients maintain a healthy diet with adequate caloric intake. However, weight gain may only be successful after reducing the inflammation with prescription medications. If the bowel becomes narrowed (strictured) because of chronic Crohn’s disease activity, then patients may be at risk of bowel obstruction. In this case, a low residue diet that eliminates non-digestible vegetables may be recommended. For all patients, stopping smoking is an important part of any therapy for this disease.


    What medications are right for me?

    What are the side effects of the medication?

    Is there a link between Crohn's disease and colon cancer?

    What is the chance that my children will get Crohn’s disease?

    Can I become pregnant if I have Crohn’s disease?

    Editorial review provided by VeriMed Healthcare Network.