The basics of Crohn's disease

An estimated 500,000 Americans have Crohn's disease, an inflammatory bowel disease (IBD) that causes chronic inflammation of the intestinal tract. Like ulcerative colitis, another common IBD, Crohn's disease can be both painful and debilitating and sometimes may lead to life-threatening complications.

Crohn's disease - also called ileitis or enteritis - can affect any area of the GI tract, from the mouth to the anus. The swelling extends deep into the lining of the affected organ. The swelling can cause pain and can make the intestines empty frequently, resulting in diarrhea.

Because the symptoms of Crohn's disease are similar to other intestinal disorders, such as irritable bowel syndrome and ulcerative colitis, it can be difficult to diagnose. Ulcerative colitis causes inflammation and ulcers in the top layer of the lining of the colon. In Crohn's disease, all layers of the intestine may be involved, and normal healthy bowel can be found between sections of diseased bowel.

Crohn's disease affects men and women equally and seems to run in some families. About 20 percent of people with Crohn's disease have a blood relative with some form of inflammatory bowel disease, most often a brother or sister and sometimes a parent or child. Crohn's disease can occur in people of all age groups, but it is more often diagnosed in people between the ages of 20 and 30. Recent data suggests that there is an increased risk of cancer of the small intestine and colon in patients with long-standing Crohn's disease.

What causes Crohn's disease?

The cause of Crohn's disease is unknown. Some scientists suspect that infection by certain bacteria may be the cause of Crohn's disease. However, there has been no convincing evidence that the disease is caused by infection. Crohn's disease is not contagious. Although diet may affect the symptoms in patients with Crohn's disease, it is unlikely that diet is responsible for the disease. Activation of the immune system in the intestines appears to be important in Crohn's disease. The immune system is composed of immune cells and the proteins that these immune cells produce. Normally, these cells and proteins defend the body against harmful bacteria, viruses, fungi and other foreign invaders. Activation of the immune system causes inflammation within the tissues where the activation occurs.

What are the symptoms of Crohn's?

The most common symptoms of Crohn's disease are abdominal pain, often in the lower right area, and diarrhea. Rectal bleeding, weight loss, arthritis, skin problems, and fever may also occur. Bleeding may be serious and persistent, leading to anemia. Children with Crohn's disease may suffer delayed development and stunted growth. The range and severity of symptoms varies.

What are the complications of Crohn's disease?

In the early stages, Crohn's disease causes small, scattered, shallow, crater-like erosions on the inner surface of the bowel. With time, the erosions become deeper and larger, ultimately becoming ulcers (which are deeper than erosions) and causing scarring and stiffness of the bowel. As the disease progresses, the bowel becomes increasingly narrowed, and ultimately can become obstructed. Obstruction often occurs suddenly by poorly-digestible fruit or vegetables that plug the already-narrowed segment of the intestine. When the intestine is obstructed, digesting food, fluid and gas from the stomach and the small intestine cannot pass into the colon.

Deep ulcers can puncture holes in the wall of the bowel, and bacteria from within the bowel can spread to infect adjacent organs and the surrounding abdominal cavity.

Nutritional complications, such as deficiencies of proteins, calories, and vitamins, are common in Crohn's disease.

Other complications associated with Crohn's disease include arthritis, skin problems, inflammation in the eyes or mouth, kidney stones, gallstones, or other diseases of the liver and biliary system. Some of these problems resolve during treatment for disease in the digestive system, but some must be treated separately.