Diarrhea

Diarrhoea
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ICD-10 A09, K58, K59.1
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ICD-9 009.2-009.3, 558.9, 564.5
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Diarrhea ( American English) or diarrhoea ( Commonwealth English) is a condition in which the sufferer has frequent and watery, chunky, or loose bowel movements (from the ancient Greek word διαρροή = leakage; lit. "to run through"). In the Third World, diarrhea is the most common cause of death among infants, killing more than 1.5 million per year.

Causes

This condition can be a symptom of injury, disease, allergy, food intolerance ( fructose, lactose), foodborne illness or extreme excess of Vitamin C and is usually accompanied by abdominal pain, and often nausea and vomiting. 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 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 myriad viral infections but is also often the result of 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.

It can also be a symptom of more serious diseases, such as dysentery, cholera, or botulism and can also be indicative of chronic syndromes such as Crohn's disease or ulcerative colitis. Though appendicitis patients don't generally have diarrhea, it is a common symptom of a ruptured appendix. It is also an effect of severe radiation sickness.

It can also be caused by excessive alcohol consumption.

Symptomatic treatment for diarrhea involves the patient consuming adequate amounts of water to replace lost fluids, preferably mixed with electrolytes to provide essential salts and some amount of nutrients. For many people, further treatment and formal medical advice is unnecessary. The following types of diarrhea generally indicate medical supervision is desirable:

  • Diarrhea in infants.
  • Moderate or severe diarrhea in young children.
  • Diarrhea associated with blood.
  • Diarrhea that continues for more than 2 weeks.
  • Diarrhea that is associated with more general illness such as non-cramping abdominal pain, fever, weight loss, etc.
  • Diarrhea in travelers (more likely to have exotic infections such as parasites)
  • Diarrhea in food handlers (potential to infect others)
  • Diarrhea in institutions ( Hospitals, child care, mental health institutes, geriatric and convalescent homes, etc.).

Since most people will ignore very minor diarrhea, a patient who actually presents to a doctor is likely to have diarrhea that is more severe than usual.

Mechanism

To evacuate 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 transport. This causes both Cl- and HCO3 to follow passively, as well as water. Now in the intestines, the water dilutes toxins as well as triggers contractions of the intestine due to increase in intestinal distension. These contractions push the contents of the lower GI tract towards and out of the anal canal. Medications such as loperamide are designed to prevent such contractions in response to the distension, and should not be used to prevent diarrhea. Such inhibition actually prolongs the infection or irritation, and can cause a worsening over time because the evacuation of the bowel contents has been delayed.

Acute diarrhea

This may be defined as diarrhea that lasts less than 2 weeks, and was also called gastroenteritis. The suffix "itis" stands for inflammation, often not present, so this name is being phased out.

Acute diarrhea can nearly always be presumed to be infective, although only in a minority of cases is this formally proven.

It is often reasonable to reassure a patient, ensure adequate fluid intake, and wait and see. In more severe cases, or where it is important to find the cause of the illness, stool cultures are instituted.

The most common organisms found are Campylobacter (an organism of animal origin), salmonella (also often of animal origin), Cryptosporidium (animal origin), Giardia Lamblia (lives in drinking water). Shigella (dysentery) is less common, and usually human in origin. Cholera is rare in Western countries. It is more common in travelers and is usually related to contaminated water (its ultimate source is probably sea water). Escherichia coli is probably a very common cause of diarrhea, especially in travelers, but it can be difficult to detect using current technology. The types of E. coli vary from area to area and country to country.

Viruses, particularly rotavirus, are common in children. (Viral diarrhea is probably over-diagnosed by non-doctors.) The Norwalk virus is rare.

Toxins and food poisoning can cause diarrhea. These include staphylococcal toxin (often milk products due to an infected wound in workers), and Bacillus cereus (eg rice in Chinese takeaways). Often "food poisoning" is really salmonella infection.

Parasites and worms sometime cause diarrhea but often present with weight loss, irritability, rashes or anal itching. The most common is pinworm (mostly of nuisance value rather than a severe medical illness). Other worms, such as hookworm, ascaria, and tapeworm are more medically significant and may cause weight loss, anemia, general unwellness and allergy problems. Amoebic dysentery due to Entamoeba histolytica is an important cause of bloody diarrhea in travelers and also sometimes in western countries which requires appropriate and complete medical treatment.

Chronic diarrhea

Infective diarrhea

It is not uncommon for diarrhea to persist. Diarrhea due to some organisms may persist for years without significant long term illness. More commonly a diarrhea will slowly ameliorate but the patient becomes a carrier (harbors the infection without illness). This is often an indication for treatment, especially in food workers or institution workers.

Parasites (worms and amoeba) should always be treated. Salmonella is the most common persistent bacterial organism in humans.

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 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

These are of unknown origin but are likely to be abnormal immune responses to infection. There is some overlap but the two types are ulcerative colitis and Crohn's disease:

  • 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

Irritable bowel syndrome is of unknown origin but often results from an insult to the gut, and as such can overlap with infective diarrhea, celiac, and inflammatory bowel diseases. IBS is a brain-gut dysfunction that causes visceral hypersensitivity and results in chronic diarrhea (or constipation) in association with lower abdominal pain or discomfort. While there is no direct treatment for the underlying pathology of IBS, symptoms, including diarrhea, can be well managed through a combination of dietary changes, soluble fiber supplements, and/or medications.

Other important causes

  • Ischaemic 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 colon is most common.)
  • Hormone-secreting tumors: some hormones (e.g. serotonin) can cause diarrhea if excreted to 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.

Treatment of diarrhea

  1. Keep hydrated. This is the most appropriate treatment in most cases of minor diarrhea.
  2. Try eating more but smaller portions. Eat regularly. Don't eat or drink too quickly.
  3. Intravenous fluids or a "drip": Sometimes, especially in children, dehydration can be life-theatening and intravenous fluid may be required.
  4. Oral rehydration therapy: Taking a sugar/salt solution, which can be absorbed by the body.
  5. Opioids and their analogs should not be used for infectious diarrhea as they are said to prolong the illness and may increase the risk of a carrier state. Opioids are the most effective antidiarrheals available. Their principal method of action is to inhibit peristalsis. Loperamide, also known as Imodium, is the most commonly used antidiarrheal. Loperamide is chemically related to the drug meperidine or Demerol, but does not cross the blood-brain barrier and does not appear to induce tolerance or dependence. Other opioids used to control diarrhea (in increasing order of strength) are: Lomotil ( diphenoxylate with atropine); Lonox ( difenoxin with atropine); codeine; opium tincture (laudanum); and morphine. The most potent opioids are generally reserved for chronic diarrhea (e.g., from complications of AIDS).
  6. Antibiotics: antibiotics may be required if a bacterial cause is suspected and the patient is medically ill. They are sometimes also indicated for workers with carrier states in order to clear up an infection so that the person can resume work. Parasite-related diarrhea (e.g. giardiasis) require appropriate antibiotics. Antibiotics are not routinely used, as the cause is rarely bacterial and antibiotics may further upset intestinal flora and worsen rather than improve the diarrhea. Clostridium difficile-associated diarrhea and pseudomembranous colitis is often caused by antibiotic use.
  7. Dietary manipulation: in particular, patients with celiac disease should avoid wheat products. Patients with Irritable Bowel Syndrome can make dietary changes to prevent the over-reaction of their gastrocolic reflex that results in diarrhea. Having soluble fiber foods and supplements, substituting soy or rice products for dairy, being careful with fresh fruits and vegetables that are high in insoluble fiber, and eating regular small amounts can all help to lessen the symptoms of IBS (Van Vorous 2000). Foods and beverages to be avoided or minimized include red meat, oily or fatty (and fried) products, dairy (even when there is no lactose intolerance), solid chocolate, coffee (regular and decaffeinated), alcohol, carbonated beverages (especialy those also containing sorbitol) and artificial sweeteners (Van Vorous 2000). Several of the most common dietary triggers are well-established by clinical studies at this point; research has shown that IBS patients are hypersensitive to fats, insoluble fibers, and fructose (Caldarella, 2005; Whorwell, 1994; Choi, 2003).
  8. Hygiene and isolation: Hygiene is important in limiting spread of the disease.
  9. It is claimed that some fruit, such as bananas, mangoes, papaya and pineapple may have positive effects on this condition. Bananas have the merits of being easily obtainable, and they are unlikely to have any other significant unwanted side effects. Bananas and mangoes are high in soluble fiber, which can help regulate water content in the bowel and alleviate diarrhea. Mucilage, which you can obtain in capsule form, may be helpful for the same reason. Mucilage can also be used as cereal for babies, as it is easily digested. The high acid content of pineapple may make this food a bad choice for people suffering from chronic diarrhea.