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In medicine, diarrhea, also spelled diarrhoea (see spelling differences), refers to frequent loose or liquid bowel movements. Acute diarrhea due to viral gastroenteritis is a common cause of death in developing countries and is a major cause of infant death worldwide.
Look up diarrhea in Wiktionary, the free dictionary.
This condition can occur as a symptom of infection, allergy, food intolerance, foodborne illness and/or extreme excesses of Vitamin C and/or magnesium and may be accompanied by abdominal pain, nausea and vomiting. Temporary diarrhea can also result from the ingestion of laxative medications or large quantities of certain foods like prunes with laxative properties. There are other conditions which involve some but not all of the symptoms of diarrhea, and so the formal medical definition of diarrhea involves defecation of more than 200 grams per day (though formal weighing of stools to determine a diagnosis is rarely actually carried out).
Diarrhea occurs when insufficient fluid is absorbed by the colon. As part of the digestion process, or due to fluid intake, food is mixed with large amounts of water. Thus, digested food is essentially liquid prior to reaching the colon. The colon absorbs water, leaving the remaining material as a semisolid stool. If the colon is damaged or inflamed, however, absorption is inhibited, and watery stools result.
Diarrhea is most commonly caused by viral infections or bacterial toxins. In sanitary living conditions and with ample food and water available, an otherwise healthy patient typically recovers from the common viral infections in a few days and at most a week. However, for ill or malnourished individuals diarrhea can lead to severe dehydration and can become life-threatening without treatment.
Diarrhea can also be a symptom of more serious diseases, such as dysentery, Montezuma's Revenge, cholera, or botulism, and can also be indicative of a chronic syndrome such as Crohn's disease. Though appendicitis patients do not generally have diarrhea, it is a common symptom of a ruptured appendix. It is also an effect of severe radiation sickness.
Diarrhea can also be caused by dairy intake in those who are lactose intolerant.
Symptomatic treatment for diarrhea involves the patient consuming adequate amounts of water to replace that loss, preferably mixed with electrolytes to provide essential salts and some amount of nutrients. For many people, further treatment is unnecessary. The following types of diarrhea generally indicate medical supervision is desirable:
A severity score is used to aid diagnosis.
To expel the contents of the lower digestive tract, the fluidity of the contents of the small and large intestines is increased. Active transport of Na+ back into the gut initiates a reverse sodium (Na+) transport. This causes both Cl– and HCO3– to follow passively, as well as water. Once in the intestines, the large volume of water dilutes toxins and distends the intestinal walls. This distention triggers the intestines to contract, pushing their contents towards and out of the anal canal.
Types of diarrhea
There are at least four types of diarrhea: secretory diarrhea, osmotic diarrhea, motility-related diarrhea, and inflammatory diarrhea.
Secretory diarrhea means that there is an increase in the active secretion, or there is an inhibition of absorption. There is little to no structural damage. The most common cause of this type of diarrhea is a cholera toxin that stimulates the secretion of anions, especially chloride ions. Therefore, to maintain a charge balance in the lumen, sodium is carried with it, along with water.
Osmotic diarrhea occurs when there is a loss of water due to a heavy osmotic load. This can occur when there is maldigestion (e.g., pancreatic disease or Coeliac disease), where the nutrients are left in the lumen, which pulls water into the lumen.
Motility-related diarrhea occurs when the motility of the gastrointestinal tract is abnormal. If the food moves too quickly, there is not enough contact time between the food and the membrane, meaning that there is not enough time for the nutrients and water to be absorbed. This can follow a vagotomy or diabetic neuropathy.
Inflammatory diarrhea occurs when there is damage to the mucosal lining or brush border, which leads to a passive loss of protein-rich fluids, and a decreased ability to absorb these lost fluids. Features of all three of the other types of diarrhea can be found in this type of diarrhea. It can be caused by bacterial infections, viral infections, parasitic infections, or autoimmune problems such as inflammatory bowel disease.
Causes include celiac disease (intolerance to gluten, a wheat product), lactose intolerance (Intolerance to milk sugar, common in non-Europeans), fructose malabsorption, pernicious anemia (impaired bowel function due to the inability to absorb vitamin B12), loss of pancreatic secretions (may be due to cystic fibrosis or pancreatitis), short bowel syndrome (surgically removed bowel), radiation fibrosis (usually following cancer treatment), and other drugs such as chemotherapy.
Inflammatory bowel disease
The two overlapping types here are of unknown origin:
Irritable Bowel Syndrome
Another possible cause of diarrhea is Irritable Bowel Syndrome (IBS). Symptoms defining IBS: abdominal discomfort or pain relieved by defecation and unusual stool (diarrhea or constipation or both) or stool frequency, for at least 3 days a week over the previous 3 months. IBS symptoms can be present in patients with a variety of conditions including food allergies, infective diarrhea, celiac, and inflammatory bowel diseases. Treating the underlying condition (celiac disease, food allergy, bacterial dysbiosis, etc.) usually resolves the diarrhea. IBS can cause visceral hypersensitivity. While there is no direct treatment for undifferentiated IBS, symptoms, including diarrhea, can sometimes be managed through a combination of dietary changes, soluble fiber supplements, and/or medications.
Other important causes
Chronic diarrhea can be caused by chronic ethanol ingestion. Consumption of alcohol affects the body's capability to absorb water - this is often a symptom that accompanies a hangover after a heavy drinking session. The alcohol itself is absorbed in the intestines and as the intestinal cells absorb it, the toxicity causes these cells to lose their ability to absorb water. This leads to an outpouring of fluid from the intestinal lining, which is in turn poorly absorbed. The diarrhea usually lasts for several hours until the alcohol is detoxified and removed from the digestive system. Symptoms range from person to person and are influenced by both the amount consumed as well as physiological differences. Alcohol-induced diarrhea is often accompanied by "the follow through" where a feeling that the patient is going to break wind (flatulence) instead becomes an uncontrolled episode of diarrhea.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Diarrhea". A list of authors is available in Wikipedia.|