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What is inflammatory bowel disease?
Crohn's disease and ulcerative colitis are inflammatory diseases of the
gastrointestinal tract. As a group, these conditions are referred to as
inflammatory bowel disease (IBD). Although these diseases share common features,
they also have significant differences, especially in the sites that are
affected, treatment of the disease, prognosis and complications.
What causes inflammatory bowel disease?
The cause of IBD remains unknown, but there is undoubtedly a genetic
predisposition to the disease. Up to 25% of patients with IBD have a first
degree relative with the disease, and siblings and children of patients with IBD
have a 5 to10% risk of developing IBD in their lifetime.
Who is at risk for inflammatory bowel disease?
All populations are at risk, but inflammatory bowel disease is more common
in Caucasians. In fact, the highest risk group is Ashkenazi Jews living in
Northern Europe or in the United States.
What happens in inflammatory bowel disease?
IBD is characterized by an abnormal immunological response in the
gastrointestinal system.
In a healthy individual, the gastrointestinal system has a huge number of
inflammatory cells that destroy harmful substances that are ingested. For
example, bacteria are initially destroyed by acid in the stomach, and bacteria
that enter into the small bowel are destroyed by the local immune system. When
the immune system is overwhelmed or fails, we get ill.
In IBD, for reasons that are not yet determined, the gastrointestinal system
fails, and the immune system becomes activated and does not turn itself off. In
fact, the immune system even attacks some of the proteins that are normally
present in the gastrointestinal system, since it fails to recognize them as part
of our body. As a result, uncontrolled inflammation occurs.
It is not known whether this abnormal response is caused by infectious
agents, dietary substances or environmental factors. So far, no bacteria, virus
or food has been found to be responsible for initiating the abnormal immune
response.
What are the symptoms of ulcerative colitis?
Ulcerative colitis affects only the large intestine. It does not affect the
esophagus, stomach or the small intestine. It affects only the inner layer of
the colon (mucosa), and does so in a continuous pattern. The inflammation begins
in the rectum and then spreads to other segments of the colon.
Patients with ulcerative colitis usually have non-bloody diarrhea that
subsequently becomes bloody. Most patients have mild symptoms that progress
slowly, but occasionally the symptoms can be very dramatic with severe bloody
diarrhea, abdominal pain and fever.
Infections of the gastrointestinal tract are the main conditions that mimic
ulcerative colitis.
How is ulcerative colitis diagnosed?
It is important to provide a specific diagnosis in order to provide adequate
treatment. The extent of the disease determines the prognosis (probable outcome)
and helps to determine the optimal route of treatment.
To diagnose ulcerative colitis, the following are necessary:
- Complete history and physical examination
- Blood tests and stool samples
- Endoscopic examination of the colon with biopsies
- X-ray to determine the presence or absence of a perforation
(for patients with a severe case of ulcerative colitis)
How is ulcerative colitis treated?
Ulcerative colitis runs a chronic course that is characterized by periods of
inactivity and periods of activity.
5-ASA
The principle treatment is a medication called 5-aminosalycilic acid
(5-ASA). Since this medication needs to be in contact with the diseased bowel to
be effective, the 5-ASA is either bound to other substances that release the
medication in the colon; or the 5-ASA is protected by a "coat" that
dissolves when the capsule enters into the colon.
This medication comes in different presentations: it is available in the form
of suppositories and enemas. The original substance bound to 5-ASA is a
sulfa-based drug. For patients who are allergic to sulfa or who develop side
effects such as headache or nausea, 5-ASA is available in different preparations
that do not contain sulfa.
When the disease is limited to the rectum, it can be treated with
suppositories, if it involves only the lower part of the colon, enemas are
adequate, but if the disease is more extensive, then the medication should be
taken by mouth. When remission is achieved, the continuous use of 5-ASA
decreases the risk and frequency of having a relapse.
Corticosteroids
Corticosteroids are antiinflammatory medications that are used when 5-ASA is
ineffective in inducing remission. Corticosteroids are also used to treat
patients who have more severe disease.
The use of corticosteroids is limited by side effects and the potential for
long-term complications. In general, corticosteroids are used for short periods
of time to induce remission. Then, the remission is prolonged with a 5-ASA
medication.
Other treatment methods
For patients who fail to respond to the treatment methods mentioned previously,
other immunosupressive medications such as 6-Mercaptopurine (6-MP), Azathioprine
or Cyclosporine-A may be used.
Patients may require surgery, in which the colon is removed.
How is ulcerative colitis monitored?
Patients with extensive ulcerative colitis are at increased risk of
developing colorectal cancer. Usually colorectal cancer in these patients is
preceded by mucosal changes that can be diagnosed on pathology.
After 7 to 10 years of having extensive disease, patients with ulcerative
colitis are advised to have screening colonoscopies with biopsies every 1 to 3
years because of their increased risk of developing colorectal cancer.
What is Crohn's disease?
Crohn's disease is an inflammatory condition of the gastrointestinal system
that can affect any segment of the gastrointestinal tract.
The most common site involved at time of presentation is the distal small
intestine and colon, followed by small intestinal involvement alone and then by
colonic involvement alone.
A major difference between ulcerative colitis and Crohn's disease is that in
Crohn's disease, the inflammation extends beyond the mucosa and involves all the
walls of the bowel. This explains why patients with Crohn's disease are prone to
developing fistulas and abscesses. Crohn's disease can behave in different ways,
causing strictures (narrowing), inflammation or fistulas (abnormal
communications between bowel and bowel, or bowel and other organs).
What are the symptoms of Crohn's disease?
The symptoms of Crohn's disease depend largely on the sites of involvement
and the type of involvement:
- Patients with strictures have signs and symptoms of
obstruction.
- Patients with inflammation usually have diarrhea, weight loss
and low grade fever.
- Patients with abscess have fever and pain.
- Patients with a fistula have various symptoms, depending on
where the fistula is and what organs are affected. For example, a patient
who has a fistula between the colon and bladder has urinary symptoms. A
patient who has a fistula between the colon and the stomach has diarrhea and
weight loss. A patient who has a fistula in the rectal area has pain and
infection in the rectum.
How is Crohn's disease treated?
The medical treatment for Crohn's disease is similar to that of ulcerative
colitis. However, besides 5-ASA, corticosteroids and immunosuppressive
medications, antibiotics are other medications that are commonly used.
The surgical treatment for Crohn's disease is also different than that of
ulcerative colitis. Surgery in Crohn's disease is used to treat complications,
and is conservative. Crohn's disease is a recurrent disease, and after a
surgical resection, the disease returns. Therefore, extensive resections are
usually avoided in order to minimize future nutritional complications.
Extraintestinal symptoms
Patients with IBD can have extraintestinal manifestations(in addition to the
intestinal symptoms), some of which run a parallel course with the disease and
others are independent of the disease activity.
The most common extraintestinal manifestations involve the:
- Musculoskeletal system in the form of joint pain or swelling
- Skin in the form of tender "lumps" (erythema nodosum)
or ulceration (Pyoderma gangrenosum)
- Liver in the form of sclerosing cholangitis
- Eyes in the form of conjunctivitis, uveitis or
keratoconjunctivitis
Diet
Nutritional deficiency is one of the main complications in patients with IBD.
Most patients lose weight, usually due to inadequate intake of nutrients.
Patients with IBD eat less because of anorexia or because the symptoms of the
disease are worsened by eating food.
In general, patients should eat a balanced diet. In the absence of strictures
and symptoms of obstruction, no food restriction is necessary. Vitamin and
mineral supplements should be prescribed individually, since there may not be a
need for it, especially for those patients who do not have malabsorption.
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