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Overview of diarrhea

Diarrhea is a common symptom that can range in severity from an acute, self-limited episode to a severe, life-threatening illness.

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A symptom of different diseases, diarrhea is characterized as an increase in the volume, consistency or frequency of fecal excretion compared to the patient’s normal stools.1 Clinical features vary depending on the cause, duration and severity of the diarrhea, and on the patient’s general health.

Diarrhea is potentially serious if it leads to dehydration or electrolyte imbalances, particularly in infants, children, elderly or other at risk groups. Accurately defining and classifying diarrhea provide the basis for appropriate approach on the diagnostic and therapeutic options. In general, supportive treatment is usually sufficient. However, antibiotic or probiotic may be considered in selected patients.2

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Etiology and Pathophysiology (How diarrhea develops)

Diarrhea may be defined as acute if the episode is <2 weeks, persistent if 2–4 weeks, and chronic if >4 weeks in duration.3 Acute diarrhea with a sudden onset is often acquired by fecal-oral transmission via direct contact or through ingestion of food or water contaminated with fecal pathogens. Chronic diarrhea is seen in conditions such as inflammatory bowel disease, celiac disease, irritable bowel syndrome and diabetic diarrhea or with certain medications.

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Causes of diarrhea

Diarrhea results from an imbalance in the absorption and secretion properties of the intestinal tract.

There are four types of diarrhea:

Osmotic diarrhea

Osmotic diarrhea occurs when ingested solute, which is not fully, absorbed draws fluid into the small intestine as seen in lactose intolerance.

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Secretory diarrhea

Secretory diarrhea occurs when the intestine secrete rather than absorb electrolytes and water as that seen with bacterial toxins.

Exudative diarrhea

Exudative diarrhea observed in inflammatory diseases when mucosal inflammation and ulceration cause outpouring of plasma, mucus and blood into the stool.

Motility disorder

Motility disorder caused by conditions such as diabetic neuropathy.

Clinical Features (Symptoms of diarrhea)

Patients with diarrhea present with various clinical features depending on the underlying cause.

Diarrhea due to small intestinal disease is typically watery and often associated with dehydration.

Diarrhea of the large intestine is associated with frequent small-volume stools, urgency and the presence of blood.

Patients with acute infectious diarrhea typically present with nausea, vomiting, abdominal pain and fever.

Parasites such as Giardia lamblia and Cryptosporidium spp. usually cause only mild abdominal discomfort associated with steatorrhea and bloating. Dehydration can occur if diarrhea is severe and when oral intake is limited due to nausea and vomiting.

Symptoms of dehydration

Dehydration is manifested as increased thirst, decreased urinary output and orthostatic changes. In severe cases, it may lead to acute renal failure and mental status changes.

Diagnosis of diarrhea

Although most diarrheal episode is benign, a thorough history and physical examination will identify those cases requiring early diagnostic evaluation or aggressive management.

The presence of comorbid diseases and associated symptoms increase the urgency for diagnostic workup and management. Abnormal vital signs, high fever, presence of moderate-to-severe dehydration or bloody diarrhea identify patients at higher risk who require early therapeutic intervention.

Management of diarrhea

The goals of treatment are

  • To maintain hydration
  • Treat the underlying causes
  • Relieve the symptoms of diarrhea

Rehydration and correction of any electrolyte imbalance is the core in the management of diarrhea. If diarrhea is secondary to another condition, treatment of the primary disorder is important.4

Nonpharmacologic Approach

  • Avoid high-fiber foods, fats, milk, caffeine and alcohol.
  • A bland diet such as bananas, toast, salted crackers, clear soups and boiled vegetables may be helpful.
  • Children who are not dehydrated should continue to be fed age-appropriate diets.
  • Oral rehydration therapy (ORT) is the preferred treatment for replacement of fluid and electrolyte losses in those with mild-to-moderate dehydration.
  • Intravenous fluid therapy is required for severe dehydration.

Pharmacologic Approach

  • The antimotility agents such as loperamide are generally not indicated. However, it may be helpful in patients with mild-to-moderate secretory diarrhea.
  • Specific antibiotic treatment is not usually required, except for invasive or dysenteric diarrhea and in immunosuppressed patients.
  • Lactobacillus preparations may be effective in restoring normal bowel flora when diarrhea is due to the administration of antibiotics.

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1.Müllhaupt B. Diarrhea. Praxis (Bern 1994). 2002; 91(42): 1749–1756.

2.Scheidler MD, Giannella RA. Practical management of acute diarrhea. Hosp Pract (Minneap). 2001; 36(7): 49–56.

3.Diarrhea. Harrison’s Principles of Internal Medicine, 17e. The McGraw-Hill Companies.

4.Scheidler MD, Giannella RA. Practical management of acute diarrhea. Hosp Pract (Minneap). 2001; 36(7): 49–56.

Written by: healthplus24.com team

Date last updated: January 19, 2015