A lifelong inflammatory disease that can affect any part of the digestive tract
- Onset most common between the ages of 15 and 30
- Sometimes runs in families; more common in certain ethnic groups
- Smoking is a risk factor
- Gender is not a significant factor
Crohn’s disease is a lifelong illness that usually begins in early adulthood and may cause serious ill health throughout life. Areas of the digestive tract become inflamed, causing a range of symptoms such as diarrhoea, abdominal pain, and weight loss. The disorder can occur in any part of the digestive tract from the mouth to the anus. However, the parts most frequently affected are the ileum (the last part of the small intestine) and the colon (the major part of the large intestine). Inflammation often occurs in more than one part of the digestive tract, with unaffected or mildly affected areas between the inflamed areas.
Crohn’s disease is a relatively uncommon disorder; about 60,000 people are affected in the UK. In Europe and North America, the condition most commonly affects white people, especially those of Jewish origin, and the onset of symptoms usually occurs between the ages of 15 and 30. The symptoms of Crohn’s disease tend to recur despite treatment, and the condition is lifelong.
The exact cause of Crohn’s disease is unknown but it is thought that it may be due to an abnormal reaction of the immune system in the intestine. Genetic factors are likely to be involved in this abnormal reaction in at least some cases, because about 1 in 10 people with Crohn’s disease has one or more relatives with the disease or another inflammatory bowel disorder. Environmental factors are also likely to be involved, especially smoking; smokers are three times more likely to develop the disease than are nonsmokers.
What are the symptoms?
The symptoms of Crohn’s disease vary between individuals. The disorder usually recurs at intervals throughout life. Episodes may be severe, lasting weeks or several months, before settling down to periods when symptoms are mild or absent. The symptoms include:
General feeling of ill health.
If the colon is affected, symptoms may also include the following:
Diarrhoea, often containing blood.
About 1 in 10 people also develops other disorders associated with Crohn’s disease. These other conditions may occur even in mild cases of Crohn’s disease and include arthritis (see Ankylosing spondylitis), eye disorders (see Uveitis), kidney stones, gallstones, and a rash (see Erythema nodosum).
Are there complications?
Complications of Crohn’s disease may include pus-filled cavities near the anus (see Anal abscess). These cavities can develop into abnormal passages between the anal canal and the skin around the anus, called anal fistulas.
Intestinal obstruction caused by thickening of the intestinal walls is a fairly common complication of Crohn’s disease. Damage to the small intestine may prevent the absorption of nutrients (see Malabsorption), and thus lead to anaemia or vitamin deficiencies. Inflammation of the colon over a long period of time may also be associated with an increased risk of developing colorectal cancer.
How is it diagnosed?
If your doctor suspects that you have Crohn’s disease, he or she may arrange for endoscopic examination of your upper bowel and of your lower bowel (see Colonoscopy). During these procedures, tissue is taken from affected areas for microscopic examination. You may also have a contrast X-ray of the intestine, known as a small bowel enema study, or a CT or MRI scan to look for intestinal abnormalities.
Blood tests may be done to check for anaemia and to assess how severely the intestine is inflamed. If your doctor suspects that you have gallstones or kidney stones, you may have imaging tests such as ultrasound scanning.
What is the treatment?
Mild attacks can often be treated with antidiarrhoeal drugs and painkillers. For an acute attack, your doctor may prescribe oral corticosteroids. As soon as symptoms subside, the dosage will be reduced to avoid the risk of side effects. If your symptoms are very severe, you may need hospital treatment with intravenous corticosteroids. In all cases, once the corticosteroid dosage has been reduced, your doctor may recommend oral sulfasalazine or mesalazine (see Aminosalicylate drugs) to reduce the frequency of attacks. Immunosuppressant drugs, such as azathioprine, may also be used for this purpose. If your symptoms do not improve with corticosteroid treatment, you may be offered biological therapy. This involves injections or intravenous infusions of drugs (known as biologicals) that block a specific protein involved in inflammation of the intestinal wall.
You may need dietary supplements, such as extra protein and vitamins, to counteract malabsorption. During severe attacks, nutrients may have to be given intravenously.
Many people who have Crohn’s disease need surgery at some stage. The procedure involves removing the diseased area of the intestine and rejoining the healthy ends (see Colectomy). However, surgery is not usually performed until it is absolutely necessary because further affected regions may develop in the remaining intestine.
What is the prognosis?
Crohn’s disease is a lifelong disorder with symptoms that recur episodically. Most affected people learn to live reasonably normal lives, but 7 in 10 people eventually need surgery. Complications and repeated surgery can occasionally reduce life expectancy. Since the disorder may increase the risk of colorectal cancer, your doctor may advise regular checkups that include colonoscopy.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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