What is Crohn's disease? 

Crohn's disease is a condition in which there is swelling, thickening and inflammation of one or more parts of the gastrointestinal tract from the mouth to the anus. Any part can be affected, but it is more common in the last part of the small bowel and colon. Other names for it include ileitis, inflammatory bowel disease, regional enteritis, granulomatous colitis.

The normal function of the bowel is to absorb the food and liquid we consume and move the waste to the rectum - this becomes the bowel motion. If parts of the bowel become inflamed due to Crohn's disease, normal absorption does not take place.

What causes Crohn's disease? 

The cause is unknown. Heredity or environmental factors may play a part in the development - one in four people with Crohn's disease have a relative with Crohn's disease or ulcerative colitis. Various theories have been suggested. These include possible infection with agents such as bacteria, viruses, chlamydiae and, most recently, mycobacteria.

Dietary factors (including chemicals and the low fibre diet consumed in modern developed countries) have also been implicated. None of these theories have been proved. 

Recent research into the heredity of Crohn's disease has identified a human gene, called NOD2, and damage to this gene is believed to be associated with the disease in about 15% of those affected. While this discovery does not hold out the immediate prospect for a cure, it does mean that more certain diagnosis may become possible. It seems that this gene plays an important role in the interaction of the body's immune system with gut bacteria.

To share your experiences of living with Crohn's disease, or to ask others with the disease how they cope, visit the online everybody Communities Crohn's and Colitis Bulletin Board.

What are the symptoms?

Symptoms depend on the location and extent of the inflammation. Chronic diarrhoea associated with abdominal pain, fever, anorexia, weight loss and a right lower abdominal pain and tenderness are the most common features. Sometimes the inflammation is so great that it blocks movement through the bowel. This can cause vomiting and/or constipation.

The faeces may sometimes contain blood or appear pale and float. The area in and around the anus can also be affected by ulcers, abscesses or fistulas (small holes in the wall of the bowel or rectum). Children may not have prominent gastrointestinal symptoms but instead have unexplained joint or bone pain, fever, anaemia or stunted growth. When only the colon is affected, the symptoms may be indistinguishable from ulcerative colitis.

Diagnosis 

Examination by your doctor and a blood test are the first steps in diagnosing Crohn's disease. Definitive diagnosis is usually made by x-ray. A referral will then be made to a radiologist for further tests. These may include:

Barium meal or barium enema

Flavoured barium solution is swallowed (meal), or fed into the bowel through the anal canal (enema), and a series of x-rays are taken which show the outline of the inside of the bowel wall.

See here for more information on barium meals and barium enemas.

Colonoscopy

Colonoscopy involves the insertion of a narrow tube into the lower bowel through the anal canal. The tube contains a small camera with its own light source that allows the specialist to look at the lining of your colon. Sometimes a small piece of tissue is removed (biopsy) so it can be examined more closely in a laboratory.

Treatment 

Crohn's disease is a chronic disorder. This means that, at present, there is no known cure. With good nutrition and medical management, however, most people with Crohn's disease usually lead normal lives.

Steroids

Symptoms of Crohn's disease are generally treated with oral steroid medications. These drugs not only reduce inflammation in the body, but restore appetite, reduce fever and diarrhoea, and relieve abdominal pain and tenderness.

Doctors try to avoid prescribing steroids on a long term basis because they have unpleasant side effects. These can include uncontrolled weight gain, swelling of the face, sugar in the urine, a rise in blood pressure or difficulty sleeping. However, for some people the disease cannot be controlled without steroids. The dosage is therefore reduced to the lowest possible level. Never stop taking steroids without consulting your doctor.

Sulphasalazines

Long term drug therapy with sulphasalazines (Pentasa, Asacol or Dipentum) is useful to suppress low grade inflammation, especially in the colon. Sulphasalazines are less effective in severe acute flare-ups. Most research has not found sulphasalazine to be helpful in preventing postoperative recurrence.

Although Crohn's disease generally causes rumbling and mild symptoms, from time to time it can flare up and cause serious illness. Initially, drugs are prescribed to reduce inflammation, subdue the body's immune system and fight infection. Food and fluid may be given by a drip directly into the bloodstream in severe cases. Other treatments which may be used in Crohn's disease include:

Immunosuppressive drugs 

The antimetabolites azathioprine and 6-mercaptopurine are effective treatments, especially when Crohn's disease involves the colon. By suppressing the immune system, they significantly improve the person's condition and allow a decrease in steroid requirements. Often, they also allow the holes that may have developed in the bowel to heal.

However, these drugs usually need to be taken for three to six months before the full benefits are experienced. Side effects can be serious and so the patient requires regular tests while on this medication. Cyclosporine, which shows promise for quicker therapeutic action, is under study.

Antibiotics

Broad-spectrum antibiotics (eg, metronidazole) may be of benefit in reducing disease activity in some patients but they are most effective for complications due to infection (eg, abscess, infected fistula).

Antibody-based treatment

The most recent approach to treating Crohn's disease is with the anti-inflammatory drugs. There are two that are currently used for Crohn's disease in New Zealand: infliximab (Remicade) and adalimumab (Humira). These drugs make use of manufactured antibodies - the molecules we all have as part of our immune system - to effectively target treatment to a particular mediator (tumour necrosis factor-alpha) involved in the inflammation of Crohn's disease. The drugs are used in moderate to severe Crohn's disease and in patients who have fistulae.

Infliximab is injected as a slow intravenous infusion taking up to two hours. This is repeated a number of times over a course, building up over a few weeks, and possibly continuing at about once every two months depending on your condition. There are a number of side effects which may mean the treatment has to be stopped: these include hypersensitivity, itching, infections, headache, difficulty breathing and pain in the bones or muscles, among others.

Treatment with adalimumab may be made available to patients whose Crohn's disease does not respond to infliximab. Adalimumab is usually given by injection into the thigh or abdomen every two weeks once the patient is established on the drug. 

Vitamin supplements

Vitamins, either injected or in tablet form, may be used to correct nutritional imbalances that can occur as a result of poor absorption of food and fluid from the bowel.

Special diets

Some patients with bowel blockages or small holes in the bowel have improved, over the short term, on hyperalimentation (giving a total food solution through a vein). An elemental diet (a total food solution given through a tube which is fed into the stomach through the nose) is used occasionally. Some children have achieved increased rates of growth with this type of treatment. These measures may be useful before an operation or in addition to other types of treatment.

Surgery

Surgery is usually necessary when the bowel persistently becomes blocked or when there are abscesses or small holes in the bowel wall. Surgical removal of the part of the bowel that is badly affected may relieve symptoms indefinitely but it does not cure the disease.

Recurrence rate after surgery, usually where the bowel has been joined, is 60 to 95%. Ultimately a further operation is required in nearly 50% of cases. Surgery is not performed unless specific complications or failure of medical therapy make it necessary. When operations have been performed, however, most patients consider their quality of life has been improved.

Established chronic Crohn's disease is characterised by lifelong recurrences. Growth retardation commonly results when the disease occurs during the developmental years. The disease rarely spreads without surgical manipulation of the bowel.

People with long-standing Crohn's disease of the small intestine carry an increased risk of small bowel cancer, and those with Crohn's colitis (Crohn's disease that is only found in the colon) have a long term risk of colon cancer.

Original material provided by the Crohn's and Ulcerative Colitis Support Group. Edited by everybody.