Crohn’s disease is a disease that causes inflammation, or swelling, and irritation of any part of the digestive tract — also called the gastrointestinal (GI) tract. The part most commonly affected is the end part of the small intestine called the ileum.
The GI tract is a series of hollow organs joined in a long, twisting tube from the mouth to the anus. The movement of muscles in the GI tract, along with the release of hormones and enzymes, allows for the digestion of food.
In Crohn’s disease, inflammation extends deep into the lining of the affected part of the GI tract. Swelling can cause pain and can make the intestine, also called the bowel, empty frequently, resulting in diarrhea. Chronic, or long-lasting, inflammation may produce scar tissue that builds up inside the intestine to create a stricture. A stricture is a narrowed passageway that can slow the movement of food through the intestine, causing pain or cramps.
Crohn’s disease is an inflammatory bowel disease (IBD), the general name for diseases that causes inflammation and irritation in the intestines. Crohn’s disease can be difficult to diagnose because its symptoms are similar to other intestinal disorders, such as ulcerative colitis and other IBDs, and irritable bowel syndrome. For example, ulcerative colitis and Crohn’s disease both cause abdominal pain and diarrhea.
Crohn’s disease may also be called ileitis or enteritis.
Who gets Crohn’s disease?
Crohn’s disease affects men and women equally and seems to run in some families. People with Crohn’s disease may have a biological relative, most often a brother or sister, with some form of IBD. Crohn’s disease occurs in people of all ages, but it most commonly starts in people between the ages of 13 and 30. Men and women who smoke are more likely than nonsmokers to develop Crohn’s disease. People of Jewish heritage have an increased risk of developing Crohn’s disease, and African-Americans have a decreased risk.
What causes Crohn’s disease?
The cause of Crohn’s disease is unknown, but researchers believe it is the result of an abnormal reaction by the body’s immune system. Normally, the immune system protects people from infection by identifying and destroying bacteria, viruses, or other potentially harmful foreign substances. Researchers believe that in Crohn’s disease the immune system attacks bacteria, foods, and other substances that are actually harmless or beneficial. During this process, white blood cells accumulate in the lining of the intestines, producing chronic inflammation, which leads to ulcers, or sores, and injury to the intestines.
Researchers have found that high levels of a protein produced by the immune system, called tumor necrosis factor (TNF), are present in people with Crohn’s disease. However, researchers do not know whether increased levels of TNF and abnormal functioning of the immune system are causes or results of Crohn’s disease. Research shows that the inflammation seen in the GI tract of people with Crohn’s disease involves several factors: the genes the person has inherited, the person’s immune system, and the environment.
What are the symptoms of Crohn’s disease?
The most common symptoms of Crohn’s disease are abdominal pain, often in the lower right area, and diarrhea. Rectal bleeding, weight loss, and fever may also occur. Bleeding may be serious and persistent, leading to anemia — a condition in which red blood cells are fewer or smaller than normal, which means less oxygen is carried to the body’s cells.
The range and severity of symptoms varies.
How is Crohn’s disease diagnosed?
To diagnose Crohn’s disease, a doctor will perform a thorough physical exam and schedule a series of tests.
Blood tests are used to look for anemia caused by bleeding, a complication of Crohn’s disease. Blood tests may also uncover a high white blood cell count, which is a sign of inflammation or infection somewhere in the body. Stool tests are commonly done to rule out other causes of GI diseases, such as infection. Stool tests can also show if there is bleeding in the intestines.
Flexible sigmoidoscopy and colonoscopy are used to help diagnose Crohn’s disease and determine how much of the GI tract is affected. Colonoscopy is used to view the ileum, rectum, and the entire colon, while flexible sigmoidoscopy is used to view just the lower colon and rectum. The computerized tomography (CT) scan uses a combination of X-rays and computer technology to create three-dimensional (3-D) images.
An upper gastinol intestinal (GI) series may be done to visually examine at the small intestine and a lower GI may be done to look at the large intestine.
Next month’s article will discuss the complications and possible treatments of Crohn’s disease.
Have questions or need support? The Crohn’s and Colitis Advocate Program offers free personalized support, education, resources, and information. Visit www.crohnsandcolitisinfo.com to learn more and sign up.
Source: digestive.niddk.nih.gov/ddiseases/pubs/crohns/