What is Crohn's disease?What is Crohn's disease?

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A chronic disease process in which the bowel becomes inflamed, leading to scarring and narrowing of the intestines.
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Related conditions: Aphthous ulcers, episcleritis, sclero-conjunctivitis, recurrent iritis, uveitis, erythema nodosum, pyoderma gangrenosum, spondyloarthropathy or spondyloarthritis-ankylosing spondylitis and sacroiliitis, peripheral arthritis, hypercoagulability, secondary amyloidosis, primary sclerosing cholangitis, gallstones, perianal disease, malnutrition, malabsorption, osteoporosis, anemia, lymphoma, cholangiocarcinoma, adenocarcinoma of the gastrointestinal tract, colorectal cancer

Definition: Crohn disease is a chronic inflammatory condition of the gastrointestinal tract, anywhere from the mouth to the anus, but most commonly in the end of the small intestine called the ileum and in the adjoining large colon.

Risk factors: Those with a family history of Crohn disease, a genetic predisposition, or a history of smoking are at greatest risk for this disease.

Etiology and the disease process: Crohn disease (CD) belongs to the group of diseases known as inflammatory bowel disease (IBD), a generic term for diseases characterized by inflammation in the small and large bowels. Other IBDs are ulcerative colitis (UC) and indeterminate colitis (lymphocytic colitis and collagenous colitis).

There are many theories about the etiology of Crohn disease, but the exact cause is unknown. It is known to run in families and be more common in certain ethnicities, suggesting a genetic predisposition. However, no specific reason or factor consistently explains the origin of the disease. The current belief relates Crohn disease to an inflammatory process. The human immune system protects people from harmful foreign substances (referred to as antigens) such as bacteria, viruses, and parasites. This protection is provided by cells and various proteins (such as antibodies) through an inflammatory reaction that is a response toward antigens or cell injuries. In Crohn disease, the immune system reacts abnormally against the affected part of the gastrointestinal tract and causes damage. This inappropriate inflammation leads to the clinical manifestations of Crohn disease.

Studies have shown that the inflammation related to Crohn disease is multifactorial and may depend on genetic factors, immune reactions, and environmental cues. A region on the human chromosome 16 was found to possibly contain genes that are involved in the abnormal inflammatory response in Crohn disease. One such gene, known as NOD2 (16q12), was found to be more common in Crohn disease patients than in the general population. An abnormality in this gene causes a mutation in the gene product (protein) that ultimately weakens the immune system’s ability to recognize harmful bacteria. The immune reaction may be a response to antigens or to modified parts of the gastrointestinal tract associated with the inflammation.

The US National Library of Medicine's Genetics Home Reference (GHR) reported in 2014 that Crohn disease is related to chromosomes 5 and 10; the IL23R gene at location 1p31.2 is also connected to the disease. In addition to NOD2, GHR states that changes in ATG16L1 (2q37.1) and IRGM (5q33.1) increase an individual's chances of developing the disease.

Antitumor necrosis factor-alpha (TNF-alpha) is a protein produced by the immune system that enhances the white blood cells’ ability to defend against infections and other foreign substances. TNF-alpha may be a cause of the inflammation associated with Crohn disease; it is abnormally elevated in Crohn disease, causing excessive inflammation and its adverse effects.

IBDs (Crohn disease and ulcerative colitis) have similar symptoms, but they also have significant differences. Crohn disease can affect any part of the gastrointestinal tract, cause inflammation deeply penetrating through the tract linings (full thickness), and show radiographic results suggestive of Crohn disease. Ulcerative colitis affects the colon and rectum; it can also cause a “backwash” ileitis in the junction of the small and large intestines. Ulcerative colitis inflammation is mainly in the superficial linings of the affected gastrointestinal tract. Tissue sampling further identifies the difference between Crohn disease and ulcerative colitis.

Incidence: The incidence of Crohn disease is 7 new cases per 100,000 people per year, and the prevalence is 162 cases per 100,000 people per year. About 20 percent of Crohn disease cases run in families. Men and women are affected equally. Crohn disease is more common in people of European and Jewish heritage than those of other ethnicities. According to GHR in 2014, the prevalence of Crohn disease in western Europe and North America, where it is most common, is 100 to 150 in 100,000 people. The onset of Crohn disease has two peaks: between the ages of fifteen and thirty and the ages of sixty and eighty. However, most patients are diagnosed before the age of thirty.

Symptoms: The manifestations of Crohn disease are heterogeneous, including symptoms within the gastrointestinal tract and outside of it (extraintestinal). Constitutional symptoms of Crohn disease are fatigue, fever, loss of appetite, and weight loss. Most common gastrointestinal tract symptoms are prolonged diarrhea, with or without rectal bleeding, and abdominal pain (tenderness), usually in the lower right area, which can be mistaken for appendicitis. Malabsorption in the gastrointestinal tract can lead to malnutrition and weight loss, which is related to delayed development and poor growth in children. Mouth ulcers may manifest along with pain in the mouth and gums. Problems of the throat such as pain or difficulty with swallowing can occur if the esophagus is involved.

Patients with Crohn disease may develop perianal diseases such as fissure in ano (fissures or tears in the lining of the anus) and fistula-in-ano (abnormal connection between the anal intestinal lining and another part of the body, such as the skin, bladder, vagina, or another part of the gastrointestinal tract). Fistulas are most common in the anal region; abscesses (pockets of pus) may be present as a complication. Blockage (obstruction) and perforation of the gastrointestinal tract may occur. Extraintestinal symptoms include eye disorders, skin problems, arthritis, and liver and gallbladder diseases.

Screening and diagnosis: Screening is done through a comprehensive physical examination and a complete blood count to evaluate for anemia and infection. A stool test will be performed if there is gastrointestinal tract bleeding or infection. Special tests for antibodies, such as antineutrophil cytoplasmic antibodies and anti-Saccharomyces cerevisiae antibodies, may be used if the diagnosis of Crohn disease is uncertain. Radiographic studies can include upper and lower gastrointestinal series (barium enema). Upper or lower gastrointestinal endoscopy can identify the affected site, allow tissue sampling (biopsy), and confirm the diagnosis of Crohn disease. The severity of Crohn disease is diverse, and its activity is described as mild-moderate, moderate-severe, severe-fulminant, and remission.

Treatment and therapy: Crohn disease has no cure; however, symptoms can be alleviated. Management of Crohn disease and its complications may include medications for treatment of symptoms such as antidiarrheal agents (loperamide and diphenoxylate), nutritional support, surgery, or a combination of these modalities. Medications for Crohn disease include antibiotics such as ciprofloxacin and metronidazole; anti-inflammatory drugs such as corticosteroids, sulfasalazine, and 5-aminosalicylate (5-ASA); immunomodulators that inhibit the immune response such as azathioprine, 6-mercaptopurine, and methotrexate; and biological therapies such as infliximab (Remicade) and adalimumab (Humira), which are antibodies that block TNF-alpha activity. All of these medications may have side effects ranging from nausea, vomiting, and headaches to infection susceptibility. The risks and benefits of medications are assessed and modifications implemented on an individual basis.

Regular nutritional assessments are necessary to prevent malnutrition, which can result from malabsorption in the inflamed small and large bowels. Surgical intervention is needed in some cases, such as failure of medical treatment and complications such as obstruction, perforation, nonstop bleeding, abscess, and fistula.

Prognosis, prevention, and outcomes: Crohn disease is a chronic medical condition. It can manifest in recurrent episodes of the active disease (flares) or remain in remission for variable time periods. Patients with Crohn disease are monitored closely for related conditions such as associated cancers. Regular cancer screening using colonoscopy is recommended for patients with Crohn disease because of its association with colorectal cancer.


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enotes eNotes educator| Certified Educator
Causes and Symptoms

Crohn’s disease is a chronic disease of the digestive system. It is one of two diseases labeled as inflammatory bowel disease (IBD); the other is ulcerative colitis. With both diseases, patients suffer from diarrhea, abdominal pain , bleeding from the rectum, and fever. The cell lining of the bowel (usually the small intestine) becomes inflamed, leading to erosion of tissues and bleeding.

Crohn’s disease may affect areas of the gastrointestinal system from the mouth to the anus. The inflammatory process may spread to include the joints, skin, eyes, mouth, and sometimes liver. In children, IBD involves a substantial risk of slow or interrupted growth.

The most common early sign is abdominal pain, often felt over the navel or on the right side. Diarrhea and subsequent weight loss often follow. Other early signs of Crohn’s disease include sores in the anal area (skin tabs), hemorrhoids, fissures (cracks), fistulas (abnormal openings from the intestines to the skin surface or other organs), abscesses (uncommon in children), and nausea and vomiting, especially in young children. Children as young as ten may develop this disease; however, in the majority of cases the onset is between the ages of thirteen and twenty-five. Some sources report that Crohn’s disease is slightly more common in women. The incidence is greater in persons of Jewish ethnic origin.

Diagnosis often is made after a series of abdominal X-rays, an upper gastrointestinal series, or a colonoscopy (visual inspection of the intestines with a camera). The gastrointestinal (GI) tract is best pictured as a continuous tube that begins at the mouth and ends at the anus. The mucosal layer of intestine that absorbs nutrients contains immune cells that act as defenders of the body (antibodies). Sometimes, this mucosal layer breaks down, and harmful bacteria enter the deep layers of the intestine. The resulting inflammatory process can entail swelling (edema), increased blood flow, and ulcerations (disruptions in the intestinal lining). In Crohn’s disease, these ulcerations involve the full thickness of the intestinal lining.

When the inflamed intestine heals, it may become scarred around the areas previously inflamed. This may lead to a narrowing of the bowel, or stricture, which can lead to partial or total blockage of the intestinal flow (bowel obstruction).

Treatment and Therapy

Crohn’s disease is a baffling, unpredictable disease for which a truly successful treatment has not been found. Some of the medications used in treatment are corticosteroids , such as prednisone and adrenocorticotropic hormone (ACTH), and sulfasalazine-type drugs, such as Azulfidine. Both have limited benefits and some side effects. Prednisone-type drugs reduce tissue inflammation and thereby relieve symptoms such as rectal bleeding, abdominal pain, and fever. They may cause side effects, including rounding of the face, increased facial hair, fluid retention, bone loss (osteoporosis), high blood pressure, and high blood sugar levels. These drugs also may cause mood swings. They are prescribed conservatively by most doctors. Sulfasalazine contains two active ingredients, a sulfa preparation(sulfapyridine) and an aspirin-like drug (5-aminosalicylic acid, or 5-ASA), which are bonded together. The 5-ASA medication is thought to act on the surface of the lining of the intestine, suppressing tissue inflammation.

The drug 6-mercaptopurine, or 6-MP, is an immunosuppressive, a substance that alters the body’s normal immune response to a disease or antigen. Immunosuppressive drugs have been used to treat autoimmune diseases, conditions in which the immune system attacks healthy tissues, among them Crohn’s disease. It is believed that these drugs can stop the mechanism that causes the body to attack itself.

Drugs can offer relief of symptoms, but no drug has yet been found to alter the long-term progression or natural course of Crohn’s disease. Following a special diet may help to alleviate some of the symptoms of Crohn's disease, as certain foods, such as alcohol or high-fiber foods, may irritate the lining the bowel further. Surgical removal of the diseased intestine is usually reserved for cases in which medical treatment has failed. The recurrence rates of Crohn’s disease following surgery are high.

Perspective and Prospects

Unlike ulcerative colitis, which affects only the inner lining of the intestines, Crohn’s disease affects the full thickness of the bowel wall. Both types of IBD occur in predominantly Western or developed countries, especially Scandinavia, the United Kingdom, Western Europe, Israel, and the United States. In recent years, IBD has been reported in Japan. IBD is seen rarely in Africa, most of Asia, and parts of South America. IBD seems to cluster in families, suggesting a genetic factor. Up to 20 percent of people with IBD have one or more blood relatives with the disease.

American gastroenterologist Burrill B. Crohn first identified Crohn’s disease in 1932. The prognosis for sufferers was poor, and their quality of life was limited. Prednisone was the first of the above-mentioned medications to be used to treat Crohn’s disease. Investigation into the causes and treatment of IBD continues in many areas, including genetic studies. Current research offers reason for optimism that the causes of IBD will be found and that a cure will follow.


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besure77 eNotes educator| Certified Educator

Crohn's disease is an inflammatory disease of the intestines and is caused by breaks or tears in the lining of the small and large intestine. Crohn's disease is related to another disease called ulcerative colitis and together they are referred to as IBD, or inflammatory bowel disease.

The cause of Crohn's disease is unknown but there are theories that it may be related to bacteria. It is not contagious. There tend to be periods of inactivity associated with this disease as well.

There are different subtypes of Crohn's disease that have different symptoms:

  1. Crohn's colitis is when the colon is inflamed. Symptoms include abdominal pain and bloody diarrhea.
  2. Crohn's enteritis is when the small intestine becomes inflamed. Symptoms include abdominal pain and diarrhea. Obstructions may also occur.
  3. Crohn's terminal ileitis affects only the end of the small intestine. Symptoms include abdominal pain and diarrhea.
  4. Crohn's entero-colitis and ileo-colitis involve both the colon and small intestine. Symptoms include abdominal pain and bloody diarrhea. Obstructions can also occur.
ako6777 eNotes educator| Certified Educator

Scientist are unsure of the causes of Crohn's disease. There is the possibility that the disease begins due to a bacterial or viral infection.  When the body begins fighting the infection the bowels become inflamed.  Genetically, there has been a link between Crohn's disease and a mutation on a gene called NOD2. Individuals with this mutation are more likely to require surgery.

The effects of Crohn's disease are can range from mild to severe.  The disease does sometimes go into remission and the sufferer will have a period of time with no symptoms.  The following are a list of symptoms of Crohn's disease.

  • Diarrhea
  • Cramping
  • Blood in your stool
  • Ulcers
  • Reduced appetite
  • Weight loss
dano7744 eNotes educator| Certified Educator

Crohn's disease is a chronic inflammatory bowel disease. It usually affects the bowels (intestines) but can cause inflammation anywhere in the GI tract. There are five types and they are named depending on which area of the GI tract is involved. Crohn's is classified as an autoimmune disorder, the body attacks itself because it can't tell the difference between good cells and bad cells.

People of all ages are affected but most commonly are between 15-35 years of age. Some signs and symptons include chronic diarrhea, abdominal pain, tenesmus (pain while having a bowel movement), fever, unexplained weight loss, and others.

Treatment includes dietary management and oral steroids.

pohnpei397 eNotes educator| Certified Educator

My brother was married to a woman with Crohn's... it's a nasty disease.

Crohn's is a type of inflammatory bowel disease.  It causes the lining of the intestines to become badly inflamed.  It can even lead to such complications as ulcers that can eat through the entire wall of an intesting.

People who suffer from Crohn's have all sorts of gastrointestinal problems (as symptoms of the disease).  They often have diarrhea.  They often have severe abdominal pain and cramping.  They have blood in their stool.

There is no cure for the disease; it can only be managed.  At least one of the treatments (Prednisone) can lead to huge weight gain.

litteacher8 eNotes educator| Certified Educator
Crohn's Disease is very uncomfortable to live with, as you can tell from the stomach problems described in the above posts. It can be managed with a specific type of diet, because certain foods seem to make the symptoms worse and others seem to help them.
kc4u | Student

It is a type of inflammatory bowel disease, an auto-immune disease affecting the Gastro-Intestinal(GI) tract causing a variety of GI symptoms like abdominal pain. diarrhea, vomiting, blood in the stool, flatulence and bloating, and also extraintestinal symptoms like inflammation in the eye, in the joints, skin infections and many more. Crohn's disease may also enhance the risk of cancer in the area of inflammation--small intestinal/colon cancer. Another complication of this disease is auto-immune hemolytic anemia which may cause fatigue and pallor. Crohn's disease may also cause neurological comlications like seizures, stoke, head-ache and depression.

lit24 | Student

Crohn's disease is a chronic disease of both the large and small intestines, but sometimes it can  affect the entire digestive system - from the mouth to the anus. It is named after the physician who in 1932 made a detailed description of it.

Till today no one knows the reason for this debilitating disease. Some say it is an infection caused by bacteria, but strangely when antibiotics are administered it only makes matters worse. Recently scientists have identified a gene - NOD2 - as being associated with this disease. Individuals with mutations of this gene are more susceptible to the disease.

In Crohn's disease the intestines are inflamed and ulcerated. As the disease progresses the ulcers perforate the intestines and the other abdominal organs are  also affected.

Anti inflammatory medications and steroids help to alleviate the symptoms and not completely cure the disease

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