Irritable Bowel Syndrome
Irritable bowel syndrome (also called IBS) is a very common "functional" (meaning that it is not the result of inflammation, tumor, surgery, etc.) bowel disease in which abnormal bowel activity (either too active, underactive, or both) results in abdominal cramping with diarrhea or loose stools, bloating, gas, or constipation. These may occur in combination or be limited to either loose stools (diarrhea) or constipation..
What is going on in the body?
Normally when a person eats, the stimulation of the food causes the muscles of the colon to contract. This contraction then pushes the stool toward the rectum and eventually to the outside of the body.
IBS causes the colon to be either more sensitive to stimulation (more active, loose bowels) or more resistant to it (constipation). So, IBS is usually divided according to the predominant pattern in each patient as IBS-C for constipation, IBS-D for diarrhea, or IBS-A for alternating or both diarrhea and constipation at different times in the same person.
What are the causes and risks of the condition?
It is not clear what causes IBS, but appears to be the result of 2 major factors including environment (emotional stress),and genetics (IBS seems to be more common in twins suggesting a inherited component).
On the level of the bowel, IBS seems to result from variations in serotonin and its product (called 5-HT) action, with too much response (loose, frequent stools) or too little (constipation).
What can be done to prevent the condition?
Since the exact cause of irritable bowel syndrome is not clear, it may be difficult to prevent. Once it is diagnosed, however, it can be treated.
How is the condition diagnosed?
To diagnose IBS, a healthcare professional begins with a careful history and physical examination. Symptoms consistent with IBS are reviewed (see above).
It is critical to exclude other, more serious diseases that cause similar symptoms (obstruction of the bowel causing constipation or colitis causing diarrhea).
After a complete history and physical, the healthcare professional may order:
a CT scan of the abdomen
a stain called a hemeoccult to check for blood in the stool.
a colonoscopy, a procedure in which a tube with a camera on the end is used to look at the intestines. This test has become a routine examination in individuals older than 50 years or sooner if there are other risks for colon cancer. A biopsy may be performed during this examination.
a complete blood count called a CBC
stool tests and cultures to look for infection, or parasites
Long Term Effects
What are the long-term effects of the condition?
Irritable bowel syndrome does not appear to damage the stomach or intestines. The long-term effects are often associated with the stress, discomfort, inconvenience and frustration over symptoms.
What are the risks to others?
Irritable bowel syndrome is not contagious and poses no risk to others.
What are the treatments for the condition?
Treatment of irritable bowel syndrome often focuses on treating the symptoms. This may include:
Patient education and behavioral therapy (including hypnosis, biofeedback, relaxation, meditation and cognitive therapy)
high fiber diets and hydration
fiber supplements for or bulk producing agents, especially those containing psyllium (i.e., Metamucil)
antiflatulents (i.e., simethicone)
constipating agents for IBS-D, such as loperamide (i.e., Immodium) or diphenoxylate/atropine (i.e., Lomotil)
antispasmodic medications to relieve bowel spasms, such as dicyclomine (i.e., Bentyl), chlordiazepoxide/clidinium (i.e., Librax), hyoscyamine (i.e., Levbid), phenobarbital/scopolamine/hyoscyamine/atropine (i.e., Donnatal)
antidepressants to decrease the pain as well as the stress and depression
probiotics may help
Drugs that increase or decrease serotonin activity in the bowel may help. For IBS-D, alosetron (i.e., Lotronex), which decreases serotonin effect and for IBS-C, tagaserod (i.e., Zelnorm), to increase serotonin action.
Newer or developing agents, not all of which have received approval from the Federal Drug Administration, include:
cilansetron, to decrease serotonin effect, for IBS-D,
renzapride, which has mixed serotonin effects, for IBS-C,
clonidine (i.e., Catapres) a blood pressure medicine, for IBS-D,
asimadoline, which reduces colon sensation and has been tried with success in IBS-C,
lubiprostone (i.e., Amitiza), which increases bowel action and is being tested in IBS-C,
dextofisopam, which has helped with IBS-D and IBS-A, and
MD-1100 (linaclotide) is just beginning study as a local drug in the colon to stimulate it for IBS-C.
The Natural Medications Comprehensive Database has evaluated the studies on a number of herbs, vitamins and supplements used for patients with IBS and lists the following as "Possibly Effective": bifidobacteria (a probiotic), blond psyllium (a bulk agent), guar gum (a bulk agent), wheat bran (a bulk agent), The NMCD lists Brahmi as "Possibly Ineffective" and concludes there is not enough evidence to recommend artichoke, capsicum, lactobacillus (a probiotic) melatonin, or peppermint.
What are the side effects of the treatments?
Each class of medications has its own side effects: alosetron (constipation, abdominal discomfort and nausea), tagaserod (headache and diarrhea), cilansetron (abdominal pain, constipation, interference with blood flow to the bowel), renzapride (diarrhea, headache), clonidine (tiredness, drop in blood pressure), asimadoline (unknown), lubiprostone (headache, diarrhea, nausea), dextofisopam (abdominal pain), MD-1100 (unknown).
What happens after treatment for the condition?
Symptoms of irritable bowel syndrome can and often do reoccur. A person with IBS needs to continue the prescribed management program for the rest of his or her life (temporary IBS has been described after bowel infections like traveler's diarrhea and after the gall bladder has been removed.). Antidepressants may not be needed after stress management or behavioral therapy.
How is the condition monitored?
Any new or worsening symptoms should be reported to the healthcare professional. Alarm symptoms in patients with IBS include: anemia or blood loss form the bowel, abnormal rectal examination by physician, development after age 50, and any abnormal laboratory tests.
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