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Crohn's disease is an ongoing
disorder that causes inflammation of the digestive tract, also referred to as
the gastrointestinal (GI) tract. Crohn's disease can affect any area of the GI
tract, from the mouth to the anus, but it most commonly affects the lower part
of the small intestine, called the ileum. 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.
Crohn's disease is an inflammatory bowel disease, the general name for diseases that cause swelling in the intestines. 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 large intestine. 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. People of Jewish heritage have an increased risk of developing Crohn's disease, and African Americans are at decreased risk for developing Crohn's disease.
Crohn's disease may also be called ileitis or enteritis.
Several theories exist about
what causes Crohn's disease, but none have been proven. The human immune system
is made from cells and different proteins that protect people from infection.
The most popular theory is that the body's immune system reacts abnormally in
people with Crohn's disease, mistaking bacteria, foods, and other substances
for being foreign. The immune system's response is to attack these "invaders."
During this process, white blood cells accumulate in the lining of the
intestines, producing chronic inflammation, which leads to ulcerations and
Scientists do not know if the abnormality in the functioning of the immune system in people with Crohn's disease is a cause, or a result, of the disease. Research shows that the inflammation seen in the GI tract of people with Crohn's disease involves several factors: the genes the patient has inherited, the immune system itself, and the environment. Foreign substances, also referred to as antigens, are found in the environment. One possible cause for inflammation may be the body's reaction to these antigens, or that the antigens themselves are the cause for the inflammation. Scientists 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.
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.
A thorough physical exam and
a series of tests may be required to diagnose Crohn's disease.
Blood tests may be done to check for anemia, which could indicate bleeding in the intestines. Blood tests may also uncover a high white blood cell count, which is a sign of inflammation somewhere in the body. By testing a stool sample, the doctor can tell if there is bleeding or infection in the intestines.
The doctor may do an upper GI series to look at the small intestine. For this test, the person drinks barium, a chalky solution that coats the lining of the small intestine, before x rays are taken. The barium shows up white on x-ray film, revealing inflammation or other abnormalities in the intestine. If these tests show Crohn's disease, more x rays of both the upper and lower digestive tract may be necessary to see how much of the GI tract is affected by the disease.
The doctor may also do a visual exam of the colon by performing either a sigmoidoscopy or a colonoscopy. For both of these tests, the doctor inserts a long, flexible, lighted tube linked to a computer and TV monitor into the anus. A sigmoidoscopy allows the doctor to examine the lining of the lower part of the large intestine, while a colonoscopy allows the doctor to examine the lining of the entire large intestine. The doctor will be able to see any inflammation or bleeding during either of these exams, although a colonoscopy is usually a better test because the doctor can see the entire large intestine. The doctor may also do a biopsy, which involves taking a sample of tissue from the lining of the intestine to view with a microscope.
The most common complication
is blockage of the intestine. Blockage occurs because the disease tends to
thicken the intestinal wall with swelling and scar tissue, narrowing the
passage. Crohn's disease may also cause sores, or ulcers, that tunnel through
the affected area into surrounding tissues, such as the bladder, vagina, or
skin. The areas around the anus and rectum are often involved. The tunnels,
called fistulas, are a common complication and often become infected. Sometimes
fistulas can be treated with medicine, but in some cases they may require
surgery. In addition to fistulas, small tears called fissures may develop in
the lining of the mucus membrane of the anus.
Nutritional complications are common in Crohn's disease. Deficiencies of proteins, calories, and vitamins are well documented. These deficiencies may be caused by inadequate dietary intake, intestinal loss of protein, or poor absorption, also referred to as malabsorption.
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.
The National Institute of
Diabetes and Digestive and Kidney Diseases (NIDDK) conducts and supports
research into many kinds of digestive disorders, including Crohn's disease.
Several clinical trials are currently evaluating the efficacy and safety of different
therapies for the treatment of Crohn's disease.
Source: Information provided courtesy of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), a division of the National Institutes of Health (NIH).
NIDDK health-related material is provided for information purposes only and does not necessarily represent endorsement by or an official position of the National Institute of Diabetes and Digestive and Kidney Diseases or any other Federal agency. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient's medical history.
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