Crohn’s disease

What is Crohn’s disease?

Crohn’s disease is a complex intestinal disorder that is characterised by chronic inflammation of parts of the digestive tract (GI). The inflammation leads to ulcers that can cause pain and diarrhea, which disturbs the normal function of the bowel. Crohn’s disease can sometimes be difficult to diagnose because its symptoms are like the symptoms of other GI diseases. Crohn’s disease can affect any area of the GI tract, but it most often affects a part of the small intestine called the terminal ileum.

Who gets Crohn’s disease?

Crohn’s disease can run in families. As many as 20 percent of people with Crohn’s disease have a relative with Crohn’s disease or Ulcerative colitis. It is most common in people between the ages of 20 and 30.  It seems to affect men and woman similarly.

What are the symptoms of Crohn’s disease?

The natural course of Crohn’s disease varies tremendously between individuals. The condition can be characterised as mild, moderate or severe. Symptoms can be quite variable from person to person. The most common symptoms are abdominal pain and diarrhea. If the large bowel is affected, people may develop bleeding from the rectum. Rectal bleeding can be serious and may not stop without medical help. Bleeding can be less obvious (occult) and lead to anaemia, Anaemia makes a person feel tired. People can also loose weight, develop skin problems, and fevers. Children with Crohn’s disease may grow more slowly than peers and may not reach their expected full height.

What causes Crohn’s disease?

The gut is effectively the skin on the inside. It has a large surface area (approx 200 m2), which allows absorption of all nutrients. It has evolved a complex immune system that in health maintains the integrity of the gut lining, allowing absorption of nutrients whilst preventing infections with bacteria and viruses that we ingest with food. Usually it is quite difficult to stimulate an immune response in the gut and there is good evidence that there are lots of “checks” in the system that have to be passed before an immune response occurs. Indeed lots of immune cells exist within the gut to prevent inflammation. In Crohn’s these “checks” fail.

Crohn’s disease is not one condition and the range of illness seen in different individuals reflects this. There are many “candidate” gene mutations that have been identified. These genes are found more commonly in people with Crohn’s disease. However genes are not the whole story and environmental factors also play an important role. Whatever the gene involved, in active Crohn’s disease there is an inappropriate immune response in the gut leading to damage to the gastrointestinal tract. This ongoing immune response disrupts normal gut function, leading to symptoms. Usually the gut has large numbers of “healthy” bacteria within it, particularly in the colon. As a consequence of inflammation, the usual barrier function of the gut is breached and this may lead to ongoing activation of the immune system. For this reason broad-spectrum antibiotics sometimes help the symptoms of Crohn’s disease.

How is Crohn’s disease diagnosed?

A detailed personal history, a physical examination, and blood tests are needed to diagnose Crohn’s disease.  A history of diarrhoea, abdominal pain and weight loss, particularly if there is a family history of inflammatory bowel disease should always raise clinical concern. If there is significant clinical concern, more detailed diagnostic tests will be required. The most sensitive tests are gastroscopy and colonoscopy. The gastroscopy will allow inspection of the oesophagus, stomach and duodenum for evidence of ulceration and facilitate biopsies of the duodenum to exclude villous atrophy, which can be seen in Crohn’s disease and more commonly in Coeliac disease (another important cause of diarrhoea and weight loss). The colonoscopy will allow direct inspection of the colon and terminal ileum (ileoscopy) and allow biopsies of the colonic mucosa (even if it looks normal it is important to biopsy the mucosa). An investigation of the entire small bowel may also be appropriate. This used to involve the ingestion of barium (barium meal and follow through). However most IBD centres are moving to MRI scanning, which seems more sensitive and does not involve the use of ionizing radiation. Other options to investigate the small bowel include pillcam.

How is Crohn’s disease treated?

Treatment for Crohn’s disease will  depends on;

The location of inflammation within the intestine

The severity of the disease (mild, moderate or severe)

What problems you already have from the disease

Previous treatments you have received

The goals of treatment are to;

Lead to a complete remission of symptoms with complete mucosal healing

Treatment may include;


Correct any nutritional deficiencies.

Liquid diet




No foods are known to cause injury or inflammation to the bowel. But when people have Crohn’s disease, hot spices, alcohol, greasy foods, and sometimes milk products may make diarrhea and abdominal pain worse. Your doctor may start you on a special diet so you get extra nutrients. High-calorie liquid supplements are often used to give you the extra calories and right amount of vitamins and minerals to keep you healthy. Interestingly a major change in diet can have a profound affect on Crohn’s inflammation. Often a liquid diet is used to treat children with Crohn’s disease that is affecting the small bowel. An elemental diet provides protein in its simplest form-amino acids.  Usually proteins are broken down to amino acids during the process of digestion in our gut, so we can absorb them. They are then re-assembled into proteins in our tissues. Giving an elemental diet helps Crohn’s inflammation in a significant proportion of people. Unfortunately it is not particularly popular and the inflammation often returns when people go back onto an ordinary diet.

Drug Treatment

Treatment will depend on whether you have mild, moderate or severe Crohn’s disease. Most forms of treatment are aimed at inhibiting the activity of the immune cells responsible for causing the inflammation. Unfortunately, these drugs are not that selective and as a result can make you more susceptible to certain infections. Initially your doctor may treat you with antibiotics or steroids. Steroids are made from natural chemicals in the body. However, steroids are used only for a short time because long-term exposure is not recommended.

Other drugs that are commonly prescribed for people with moderate and severe Crohn’s disease are; azathioprine, 6-mercaptopurine (thioguanines), methotrexate, infliximab (Remicade) or adalimumab (Humira). The goal for using these drugs is to avoid long-term steroid use, to get you better, and keep you better and tend to be used as maintenance drugs for at least a year.


Some people with Crohn’s disease may need surgery to treat blockage, fistulas, infection, and bleeding if medicines are no longer working. Surgery usually does not make a person disease-free forever. The most common surgery for Crohn’s disease is removing only the diseased section of intestine. In this operation, after the diseased piece of the intestine is cut out, the intestine is put back together. On rare occasions the surgeon cannot put the two ends back together and needs to create an outlet, or stoma, also called an ostomy. To create a stoma, an end of the small intestine that was not connected is brought out through a small opening made on the lower abdominal wall. The stoma is about the size of a quarter. A small bag is worn over the opening to collect waste, and the person empties the bag as needed.

People who have Crohn’s disease involving all or part of the large intestine may need to have their entire colon removed in an operation called a colectomy. If the whole colon is removed, a stoma is usually needed. Because people can have symptoms even after surgery, they should talk with their doctor and other patients before making a choice. People should know what to expect from surgery and decide what drugs, if any, would work best afterwards to try to stop the disease from coming back. Groups for people with Crohn’s disease can help a person find support.

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