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Diarrhea

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In medicine, diarrhea, also spelled diarrhoea (see spelling differences), refers to frequent loose or liquid bowel movements.

Although for many people diarrhea is merely unpleasant, diarrhea that is both acute and severe is a common cause of death in developing countries and a major cause of infant death worldwide. It is often due to gastroenteritis.

Diarrhea
SpecialtyInfectious diseases, gastroenterology Edit this on Wikidata

Causes

Diagram of the human gastrointestinal tract.

Diarrhea is most commonly caused by viral infections, parasites or bacterial toxins.[1] 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.[2]

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 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:

  • Diarrhea in infants
  • Moderate or severe diarrhea in young children;
  • Diarrhea associated with blood
  • Diarrhea that continues for more than two days;
  • Diarrhea that is associated with more general illness such as non-cramping abdominal pain, fever, weight loss, etc;
  • Diarrhea in travelers, since they are more likely to have exotic infections such as parasites;
  • Diarrhea in food handlers, because of the potential to infect others;
  • Diarrhea in institutions such as hospitals, child care centers, or geriatric and convalescent homes.

A severity score is used to aid diagnosis in children.[3]

Types of diarrhea

There are at least four types of diarrhea: secretory diarrhea, osmotic diarrhea, motility-related diarrhea, and inflammatory diarrhea.

Secretory 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

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

Motility-related diarrhea occurs when the motility of the gastrointestinal tract is abnormally high. If the food moves too quickly, 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.

Inflammatory diarrhea

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.

Dysentery

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. Dysentry is a symptom of, among others, Shigella, Entamoeba Histolytica, and Salmonella.

Infectious diarrhea

Main article: Infectious diarrhea

Infectious diarrhea is diarrhea caused by a microbe such as a bacterium, parasite, or virus.

Malabsorption

These tend to be more severe medical illnesses. 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 such as chemotherapy.

Inflammatory bowel disease

The two overlapping types here are of unknown origin:

  • Ulcerative colitis is marked by chronic bloody diarrhea and inflammation mostly affects the distal colon near the rectum.
  • Crohn's disease typically affects fairly well demarcated segments of bowel in the colon and often affects the end of the small bowel.

Irritable Bowel Syndrome

Main article: 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.[4] 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.[5] 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

  • Ischemic bowel disease. This usually affects older people and can be due to blocked arteries.
  • Bowel cancer: Some (but not all) bowel cancers may have associated diarrhea. Cancer of the large intestine is most common.
  • Hormone-secreting tumors: some hormones (e.g. serotonin) can cause diarrhea if excreted in excess (usually from a tumor).
  • Bile salt diarrhea: excess bile salt entering the colon rather than being absorbed at the end of the small intestine can cause diarrhea, typically shortly after eating. Bile salt diarrhea is a possible side-effect of gallbladder removal. It is usually treated with cholestyramine, a bile acid sequestrant.

Alcohol

Chronic diarrhea can be caused by chronic ethanol ingestion.[6] 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.

Treatment

In many cases of diarrhea, replacing lost fluid and salts is the only treatment needed. Medicines that are available without a doctor's prescription include loperamide (Imodium) and bismuth subsalicylate Pepto Bismol and Kaopectate.[7]

See also

Footnotes

  1. ^ Wilson ME (2005). "Diarrhea in nontravelers: risk and etiology". Clin. Infect. Dis. 41 Suppl 8: S541–6. doi:10.1086/432949. PMID 16267716.
  2. ^ Alam NH, Ashraf H (2003). "Treatment of infectious diarrhea in children". Paediatr Drugs. 5 (3): 151–65. PMID 12608880.
  3. ^ Ruuska T, Vesikari T (1990). "Rotavirus disease in Finnish children: use of numerical scores for clinical severity of diarrhoeal episodes". Scand. J. Infect. Dis. 22 (3): 259–67. doi:10.3109/00365549009027046. PMID 2371542.
  4. ^ Longstreth GL, Thompson WG, Chey WD, Houghton LA, Mearin F, and Spiller RC. (2006). Functional Bowel Disorders. Gastroenterology 2006; 130:1480–1491
  5. ^ Wangen, S. "The Irritable Bowel Syndrome Solution". page 113. 2006; Innate Health Publishing. ISBN 978-0-9768537-8-7. Excerpted with the author's permission at http://www.IBSTreatmentCenter.com
  6. ^ Kasper DL, Braunwald E, Fauci AS, Hauser SL, Longo DL, Jameson JL. Harrison's Principles of Internal Medicine. New York: McGraw-Hill, 2005. ISBN 0-07-139140-1.
  7. ^ Schiller LR (2007). "Management of diarrhea in clinical practice: strategies for primary care physicians". Rev Gastroenterol Disord. 7 Suppl 3: S27-38. PMID 18192963.

External links

Look up diarrhea in Wiktionary, the free dictionary.
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