In medicine, diarrhea, also spelled diarrhoea (see spelling differences), is frequent loose or liquid bowel movements, The word "diarrhea" with its odd spelling is a near steal from the Greek "diarrhoia" meaning "a flowing through." [1]. Acute diarrhea is a common cause of death in developing countries and the second most common cause of infant deaths worldwide.
Diarrhea Classification and external resources |
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ICD-10 | A09., K59.1 |
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ICD-9 | 787.91 |
DiseasesDB | 3742 |
eMedicine | ped/583 |
MeSH | D003967 |
Contents |
Diarrhea commonly results from gastroenteritis caused by viral infections, parasites or bacterial toxins.[2] In sanitary living conditions where there is ample food and a supply of clean water, an otherwise healthy patient usually recovers from viral infections in a few days. However, for ill or malnourished individuals diarrhea can lead to severe dehydration and can become life-threatening without treatment.[3]
Diarrhea can also be a symptom of more serious diseases, such as dysentery, cholera, or botulism, and can also be indicative of a chronic syndrome such as Crohn's disease or severe mushroom poisoning syndromes. Though appendicitis patients do not generally have violent 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 indicate medical supervision is required:
A severity score is used to aid diagnosis in children.[4]
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 too much water is drawn into the bowels. This can be the result of maldigestion (e.g., pancreatic disease or Coeliac disease), in which the nutrients are left in the lumen to pull in water. Osmotic diarrhea can also be caused by osmotic laxatives (which work to alleviate constipation by drawing water into the bowels). In healthy individuals, too much magnesium or vitamin C or undigested lactose can produce osmotic diarrhea and distention of the bowel. A person who does not have lactose intolerance can have difficulty absorbing lactose after an extraordinarily high intake of dairy products. In persons who do not have fructose malabsorption, excess fructose intake can still cause diarrhea. High-fructose foods that also have a high glucose content are more absorbable and less likely to cause diarrhea. Sugar alcohols such as sorbitol (often found in sugar-free foods) are difficult for the body to absorb and, in large amounts, may lead to osmotic diarrhea.
Motility-related diarrhea is caused by the rapid movement of food through the intestines (hypermotility). If the food moves too quickly through the GI tract, there is not enough time for sufficient nutrients and water to be absorbed. This can be due to a vagotomy or diabetic neuropathy, or a complication of menstruation. Hyperthyroidism can produce hypermotility and lead to pseudodiarrhea and occasionally real diarrhea. Diarrhea can be treated with antimotility agents (such as loperamide).
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 diseases. It can also be caused by tuberculosis, colon cancer, and enteritis.
Generally, if there is blood visible in the stools, it is not diarrhea, but dysentery. The blood is trace of an invasion of bowel tissue. Dysentery is caused by an excess of water by a release of antidiuretic hormone from the posterior pituitary gland. Dysentery is a symptom of, among others, Shigella, Entamoeba Histolytica, and Salmonella.
Infectious diarrhea is diarrhea caused by a microbe such as a bacterium, parasite, or virus.
Malabsorption is the inability to absorb food, mostly in the small bowel but also due to the pancreas.
Causes include celiac disease (intolerance to wheat, rye, and barley gluten, the protein of the grain), 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, including agents used in chemotherapy.
The two overlapping types here are of unknown origin:
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.[5] 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.[6] 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.
It is important to note that IBS can often be confused with Giardiasis since false negative tests for giardia can result in a misdiagnoses of the actual cause, a parasitic infection.[7]
Chronic diarrhea can be caused by chronic ethanol ingestion.[8] Consumption of alcohol affects the body's capability to absorb water - this is often a symptom that accompanies a hangover after a binge 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.
In many cases of diarrhea, replacing lost fluid and salts is the only treatment needed, either ORS (if tolerated) or intravenously. Medicines that are available without a doctor's prescription include loperamide (Imodium) and bismuth subsalicylate (as found in Pepto Bismol and Kaopectate).[9]
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