Crohn’s disease is named for Dr. Burril Crohn who, with his colleagues, first described the disease in 1932. Crohn’s disease can affect any part of the digestive system, however, it develops most often in the section of the small intestine just before the large intestine begins. This region is called the ileum, and Crohn’s disease that develops there is sometimes called ileitus. The other common site for Crohn’s disease is in the colon or large intestine.

Crohn’s disease is one of several inflammatory bowel diseases. In can be mistaken for ulcerative colitis. Both these diseases cause watery diarrhea or bloody diarrhea and abdominal cramps or pain. However, ulcerative colitis affects only the layer of cells that line the intestine forming sores or ulcers on this surface. Crohn’s disease begins in these same surface cells, but eats its way inward, damaging all four layers of the intestine and sometimes creating a hole (fistula) through the intestine and into other tissue. Another major difference between Crohn’s disease and ulcer-ative colitis is that Crohn’s disease can develop simultaneously in several spots in the digestive tract, resulting in areas of damaged with patches with healthy tissue in between. Ulcerative colitis, on the other hand, spreads uniformly across an area. Crohn’s disease is somewhat treatable, but not curable, and can cause many complications beyond the digestive system. Eventually in Crohn’s disease the walls of the intestine thicken and blockages may occur that can only be corrected by surgery.

Demographics

About half a million Americans, or 7 people out of every 100,000 have Crohn’s disease. Of these, about 4% are children under age 5, and 10% are under age 18. Most people are diagnosed with the disease between ages 15 and 35, although they may have had the disease before that. In the United States the rate of Crohn’s disease has been increasing since the 1950s.

Although most common among non-Hispanic whites, the rate of Crohn’s disease among American blacks, especially urban blacks, has been steadily increasing. Jews who trace their ancestry middle Europe are 2-4 times more likely to develop the disease than the

general white population or Jews who trace their origins to other regions. Internationally, Crohn’s disease is rare in Africa, Asia, and South America. It is more common in urban areas than in rural areas, suggesting that environment plays a role in the disease.

Causes and symptoms

At one time, researchers thought that stress and diet caused Crohn’s disease. Now researchers know that these are not factors, although both stress and diet can worsen symptoms in people who already have the disease. What researchers do know is that Crohn’s disease is caused by an inappropriate immune system reaction that affects cells in the digestive tract. Beyond that, the reasons why some people develop the disease are not clear.

There is almost certainly an inherited component that predisposes some people to the disease. Individuals who are blood relatives of a parent, sibling, or child with Crohn’s disease are 30 times more likely to develop the disease than the general population. Scientists believe multiple genes are involved in development of the disease. However, more than genetics determines who gets Crohn’s disease, because only about 44% of identical twins both develop the disease. Researchers have found several mutated (altered) genes in many, but not all, people who have Crohn’s disease but do not yet have a clear understanding of what these genes do.

KEY TERMS

Abscess—A pocket of pus formed by an infection.

Antibody—A protein produced by the immune system to fight infection or rid the body of foreign material. The foreign material that stimulates the production of antibodies is called an antigen. Specific antibodies are produced in response to each different antigen and can only inactivate that particular antigen.

Anus—The opening from the rectum to the outside of the body through which stools pass. The opening and closing of the anus is controlled by a strong ring of muscles under somewhat voluntary control.

Mineral—An inorganic substance found in the earth that is necessary in small quantities for the body to maintain a health. Examples: zinc, copper, iron.

Vitamin—A nutrient that the body needs in small amounts to remain healthy but that the body cannot manufacture for itself and must acquire through diet.

Current thinking is that interplay between genes, the environment, the individual’s health, and body chemistry affect who develops Crohn’s disease. When foreign materials (antigens) enter the body, the immune system produces antibodies, which are proteins that neutralize the foreign invader. One theory about Crohn’s disease is that some foreign organism or material stimulates an immune system response in the digestive system, and then through an error in genetic control, the response cannot be “turned off.” A second theory suggests that the cells of the immune system mistake good bacteria, food, or some other substance that is normally present in the digestive tract and make antibodies against this material as if it were a foreign substance. Either way, an inappropriate immune system response occurs that appears to be the root cause for the symptoms people with Crohn’s disease experience.

Symptoms of Crohn’s disease vary, depending on the location of the damaged cells and the length of time the individual has had the disease. Symptoms can be mild or severe. They can develop suddenly or gradually, and they may improve or even disappear, and then worsen many times throughout an individual’s life. In general, symptoms can be divided into those that affect the digestive tract and those that affect the rest of the body.

The most common symptoms that affect the digestive tract are:

chronic diarrhea, the most common symptom
abdominal pain or cramps, often in the lower right portion of the abdomen
rectal bleeding
blood in the stool, black tarry stool
ulcers in the digestive tract, usually the in the intestine
fistulas, or holes in the intestine that connect the intestine to other parts of the body such as the bladder, stomach, vagina, or another section of bowel
nausea and vomiting , usually from Crohn’s disease in the stomach
abscesses, fistulas, and ulcers around the anus, usually from Crohn’s disease in the colon. This occurs in about 45% of patients
constipation, usually after many years when the bowel has thickened and the diameter of the intestine has narrowed

Symptoms of Crohn’s disease also appear in other systems in the body. Some are the result of infection when fistulas develop. Others come from poor absorption of nutrients in the intestine over a long period. Some symptoms that occur outside the digestive tract include:

persistent low-grade fever
loss of appetite and weight loss
fatigue
anemia from blood loss and/or poor iron absorption
skin infections
eye infections
arthritis and sore joints, usually in the large joints such as the knees or hip
osteoporosis from poor calcium and vitamin D absorption
poor blood clotting from inadequate vitamin K absorption
stunted growth in children
delayed puberty

Diagnosis

Several gastrointestinal diseases can resemble the more common symptoms of Crohn’s disease. These include ulcerative colitis, irritable bowel syndrome , intestinal parasites, and intestinal obstruction. Normally the physician will begin with a medical and family history and standard blood and stool tests.

The next step toward diagnosis is usually imaging studies, most often an upper GI series. An upper GI series, sometimes called a barium swallow, includes x rays of the esophagus, stomach, and upper part of the intestine. The patient drinks a solution of barium to improve contrast on the x rays, thus the name barium swallow.

An upper endoscopy or a colonoscopy is another routine part of the diagnostic procedure. An upper endoscopy is done if abnormalities appear to be in the esophagus, stomach, or upper part of the small intestine (the duodenum). A colonoscopy uses the same technique examine the colon. These procedures are usually performed in a doctor’s office or an outpatient clinic under light sedation. A tube called an endoscope is inserted down the throat and into the stomach and duodenum or up the rectum and into the colon. At the end of the endoscope is a tiny camera that allows the doctor to see if there is damage to the cells lining digestive tract. During this procedure, the doctor also removes small tissue samples (biopsies) in order to look for abnormal cells under the microscope.

Special blood tests are available that can help differentiate between Crohn’s disease and ulcerative colitis. These tests may be done if the results of other tests are questionable. According to the Crohn’s & Colitis Foundation of America, in about 10% of patients, it is quite difficult to tell these two diseases apart.

Treatment

There is no cure for Crohn’s disease. Treatment is aimed at controlling inflammation, preventing vitamins and minerals deficiencies, and relieving symptoms. Treatment options include a combination of drugs, biologic therapies, nutritional supplements, and surgery.

Individuals with mild to moderate Crohn’s disease are usually treated first with anti-inflammatory drugs such as sulfasalazine (Azulfidine) or mesalamine (Asa-col, Rowasa, Canasa). Individuals with moderate to severe Crohn’s disease often are prescribed corticoste-roid drugs. Prendisone (Deltasone, Orasone, Metic-orten) is often the corticosteroid of choice. These drugs have significant side effects and cannot be used for long-term suppression of symptoms. Antibiotics are used to treat infection that may develop, for example, from fistula formation.

Biologic therapies use manmade antibodies. Infliximab (Remicade) is a laboratory-made antibody that blocks the production of an immune system factor that causes inflammation. This treatment is relatively new, but appears to have a good success rate for relieving symptoms. Additional biologic therapies for Crohn’s disease are under development. Individuals interested in participating in a clinical trial of a new drug or therapy for Crohn’s disease at no cost can find a list of trials currently enrolling volunteers at <http://www.clinicaltrials.gov>.

Medical treatment becomes less effective over time. When medical treatment fails or if the intestine becomes thickened and so that blockages occur, surgery may be necessary. About 80% of all people with Crohn’s disease eventually need surgery. Surgery to remove part of the intestine usually relieves symptoms for a few years, but surgery is not a cure for Crohn’s disease, and symptoms almost always return within a few years.

Nutrition/Dietetic concerns

People with Crohn’s disease tend to have vitamin and mineral deficiencies because damage to the lining of the intestine interferes with the absorption of nutrients, and chronic diarrhea hastens the loss of other nutrients. These deficiencies can cause specific disorders in other parts of the body. In addition, children with Crohn’s disease also may need special high-calorie, high-nutrient liquid supplements to maintain normal growth. A nutritionist consulting with the patient’s gastroenterologist can help determine the best diet and supplements to prevent nutritional deficiencies.

Although eating certain foods does not cause Crohn’s disease, specific foods can worsen symptoms. Many people with Crohn’s disease become lactose intolerant and must limit or eliminate dairy products from their diet. Alcohol, high fiber foods such as popcorn, and spicy foods can worsen diarrhea and abdominal cramping. Individuals must be alert to the effect of food on their symptoms until they figure out which foods to avoid.

Therapy

Crohn’s disease can be very disruptive. Individuals may be reluctant to go places or do certain things because frequent diarrhea requires them to be near a toilet. Support groups, either on the Web or in person, help many people adjust to the difficulties of living with this chronic disease. Other people find that psychotherapy (talk therapy) guided by a psychologist or psychiatrist experienced in the stresses of chronic illness can help them make a better adjustment to life with Crohn’s disease.

Prognosis

Crohn’s disease is a life-long disease. Symptoms may improve or disappear for periods, but overall, symptoms and complications tend to worsen, although the disease itself is rarely fatal. Most people with Crohn’s disease eventually need surgery as the disease becomes less and less responsive to medication. Living with Crohn’s disease can be a difficult challenge that requires major lifestyle adjustments.

Prevention

Crohn’s disease cannot be prevented.

Resources

BOOKS

Steinhart, Hillary Crohn’s and Colitis: Understanding the Facts About IBD West Toronto, Ontario: Robert Rose, 2006.

Sklar, Jill. The First Year: Crohn’s diseaseand Ulcerative Colitis: An Essential Guide for the Newly Diagnosed. 2nd ed. New York: Marlowe and Co., 2007.

Warner, Andrew S. and Amy Barto. 100 Questions & Answers About Crohn’s diseaseand Ulcerative Colitis: A Lahey Clinic Guide. Sudbury, MA: Jones and Bartlett Publishers, 2007.

Zonderman, Jon and Ronald Vender. Understanding Crohn Disease and Ulcerative Colitis Jackson, MS: University Press of Mississippi, 2006.

ORGANIZATIONS

American College of Gastroenterology. P.O. Box 342260 Bethesda, MD 20827-2260. Telephone: (301) 263-9000. Website: <http://www.acg.gi.org>

American Gastroenterological Association. 4930 Del Ray Avenue, Bethesda, MD 20814. Telephone: (301) 654-2055. Fax: (301) 654-5920. Website: <http://www.gastro.org>

Crohn’s & Colitis Foundation of America. 386 Park Avenue South, 17th Floor, New York, NY 10016. Telephone: (800) 932-2423. Website: <http://www.ccfa.org>

National Digestive Diseases Information Clearinghouse (NDDIC). 2 Information Way, Bethesda, MD 20892-3570. Telephone: (800) 891-5389. Fax: (703) 738-4929. Website: <http://digestive.niddk.nih.gov>

OTHER

Crohn’s & Colitis Foundation of America. “About Crohn’s Disease.” 2007. <http://www.ccfa.org/info/about/crohns>

Crohn’s & Colitis Foundation of America. “Living with Crohn’s Disease.” 2007. <http://www.ccfa.org/frame-viewer/?url=/media/pdf/crohns2005.pdf>

Jalta, Muralindhar and Peter Marmula. “Crohn Disease.” eMedicine.com, July 21, 2006. <http://www.emedici-ne.com/ped/topic507.htm>

Mayo Clinic Staff. “Crohn’s Disease.” MayoClinic.com, April 5, 2007. <http://www.mayoclinic.com/health/crohns-disease/DS00104>

Mayo Clinic Staff. “Crohn’s Disease: Can Diet Worsen Symptoms?” MayoClinic.com, June 2, 2006. <http://www.mayoclinic.com/health/crohns-disease/AN00353>

Medline Plus. “Crohn’s Disease.” U. S. National Library of Medicine, March 15, 2007. <http://www.nlm.nih/gov/medlineplus/crohnsdisease.html>

National Digestive Diseases Information Clearinghouse(NDDIC). “Crohn’s Disease.”February 2006. <http://digestive.niddk.nih.gov/diseases/pubs/crohns/index.htm.htm>

Wu, George and Kathleen M. Raynor. “Crohn Disease.”

eMedicine.com, January 2, 2007. <http://www.emedicine.com/med/topic477.htm>

Tish Davidson, A.M.

The Gale Encyclopedia of Diets: A Guide to Health and Nutrition