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 Diarrhea in Children: A Merck Manual of Patient Symptoms podcast
Diarrhea is frequent loose or watery bowel movements that deviate from a child's normal pattern. However, breastfed infants who are not yet receiving solid food often have frequent loose bowel movements that are considered normal.
Diarrhea may be accompanied by anorexia, vomiting, acute weight loss, fever, or passage of blood. If diarrhea is severe or prolonged, dehydration is likely. Even in the absence of dehydration, chronic diarrhea usually results in weight loss or failure to gain weight.
Diarrhea is a very common pediatric concern and causes 2 to 3 million deaths/yr worldwide. It accounts for about 9% of hospitalizations in the US among children aged < 5 yr.
For diarrhea in adults, see Symptoms of GI Disorders: Diarrhea.
Pathophysiology
Mechanisms of diarrhea may include the following:
Osmotic diarrhea results from the presence of nonabsorbable solutes in the GI tract, as with lactose intolerance. Fasting for 2 to 3 days stops osmotic diarrhea.
Secretory diarrhea results from substances (eg, bacterial toxins) that increase secretion of Cl ions and water into the intestinal lumen. Secretory diarrhea does not stop with fasting.
Inflammatory diarrhea is associated with conditions that cause inflammation or ulceration of the intestinal mucosa (eg, Crohn's disease, ulcerative colitis). The resultant outpouring of plasma, serum proteins, blood, and mucous increases fecal bulk and fluid content.
Malabsorption may result from osmotic or secretory mechanisms or conditions that lead to less surface area in the bowel. Conditions such as short bowel syndrome and conditions that speed up transit time cause diarrhea due to decreased absorption.
Etiology
The causes and significance of diarrhea (see Table 19: Approach to the Care of Normal Infants and Children: Some Causes of Diarrhea ) differ depending on whether it is acute (< 2 wk) or chronic (> 2 wk). Most cases of diarrhea are acute.
Acute diarrhea usually is caused by
Most gastroenteritis is caused by a virus; however, any enteric pathogen can cause acute diarrhea.
Chronic diarrhea usually is caused by
Chronic diarrhea can also be caused by anatomic disorders and disorders that interfere with absorption or digestion.
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Table 19
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| Some Causes of Diarrhea |
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Cause
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Suggestive Findings
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Diagnostic Approach
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Acute
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Antibiotics (eg, broad-spectrum antibiotics, multiple concomitant antibiotics)
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Temporal relationship of onset of diarrhea with taking of antibiotics
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Clinical evaluation
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Bacteria (secretory—eg, Campylobacter sp, Clostridium difficile, Escherichia coli [can cause hemolytic-uremic syndrome], Salmonella sp, Shigella sp, Yersinia enterocolitica)*
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Fever, bloody stool, abdominal pain, leukocytes in stool
Possibly petechiae or purpura
History of contact with animals at a petting zoo (E. coli); contact with reptiles (Salmonella)
History of eating undercooked food
Recent (< 2 mo) antibiotic use (C. difficile)
Day care center outbreak
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Gram stain and culture of stool
In immunocompromised patients, CBC and blood culture
If patient has recently been given antibiotics, stool testing for C. difficile toxin
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Food (allergy or poisoning)
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Allergy: Urticarial rash, lip swelling, diarrhea, difficulty breathing within minutes to several hours after eating
Poisoning: Nausea, vomiting, diarrhea
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Clinical evaluation
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Parasites (eg, Giardia intestinalis [lamblia], Cryptosporidium parvum)*
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Abdominal bloating and cramping, foul-smelling stools, anorexia
Possibly history of travel, use of contaminated water source
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Microscopic examination of stool for ova and parasites
Direct fluorescence antibody testing for ova
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Viruses (eg, astrovirus, calicivirus, enteric adenovirus, rotavirus)*
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< 5 days of diarrhea with no blood
Possibly vomiting, fever, contact with infected people
Appropriate season for the infection
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Clinical evaluation
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Chronic
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Anatomic abnormalities (eg, Hirschsprung's disease, partial small-bowel obstruction, short bowel syndrome)
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Delayed passage of stool > 48 h after birth
Bilious vomiting, abdominal distention
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Abdominal x-ray
Anorectal manometry and rectal biopsy considered if Hirschsprung's disease is suspected
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Dietary concerns (osmotic—eg, cow's milk intolerance, lactose intolerance, overfeeding, soy protein intolerance)
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> 14 days of diarrhea
Abdominal bloating, flatus, explosive diarrhea
History of excessive juice or sugary drink intake
Diarrhea after ingestion of dairy products
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Clinical evaluation
Sometimes hydrogen breath test
Test for reducing substances in stool (to check for carbohydrates) and stool pH (< 6.0 indicates carbohydrates in stool)
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Immunocompromise (eg, HIV, autoimmune enteropathy, eosinophilic gastroenteropathy, IgA or IgG deficiency)
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History of recurrent skin infections, fungal infections, weight loss, or poor weight gain
Sometimes known HIV infection
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HIV test
CBC
Ig levels
T-cell count
Complement levels
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Inflammatory disorders (eg, Crohn's disease, ulcerative colitis)
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> 14 days of diarrhea
Bloody stools, crampy abdominal pain, weight loss, anorexia, anemia, rashes
Possibly arthritis, oral ulcerations, rectal fissures
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Colonoscopy
Sometimes CT, barium enema
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Malabsorption disorders (eg, acrodermatitis enteropathica, celiac disease, cystic fibrosis)
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> 14 days of diarrhea
Fatty and foul-smelling stools, abdominal bloating, flatus, poor weight gain
Sometimes psoriasiform rash, angular stomatitis (acrodermatitis enteropathica)
History of recurrent lung infections (cystic fibrosis)
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Zinc levels
Small-bowel biopsy, antigliadin antibody, and antiendomysial antibody (celiac disease)
72-h fecal fat excretion and sweat test (cystic fibrosis)
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Other
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Constipation
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History of hard stools and fecal incontinence
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Abdominal x-ray
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*Can also cause chronic diarrhea.
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Evaluation
History
History of present illness focuses on quality, frequency, and duration of stools, as well as on any accompanying fever, vomiting, abdominal pain, or blood in the stool. Parents are asked about current or recent (within 2 mo) antibiotic use. Elements of the diet should be established; they include amounts of juice, foods high in sugar, and processed foods. Any history of hard stools or constipation should be noted. Risk factors for infection should be assessed; they include recent travel; exposure to questionable food sources; and recent contact with animals at a petting zoo, reptiles, or someone with similar symptoms.
Review of systems should seek symptoms of complications and causes. Symptoms of complications include weight loss and decreased frequency of urination and fluid intake (dehydration). Symptoms of causes include urticarial rash associated with food intake (food allergy); nasal polyps, sinusitis, and poor growth (cystic fibrosis); arthritis and anal fissures (inflammatory bowel disease); and anorexia, anemia, and rash (celiac sprue).
Past medical history should assess known causative disorders (eg, immunocompromise, cystic fibrosis, celiac sprue, inflammatory bowel disease) in the patient and family members. Drug history should be reviewed for current or recent antibiotic use.
Physical examination
Vital signs should be reviewed for indications of dehydration (eg, tachycardia, hypotension) and fever.
General assessment includes checking for signs of lethargy or distress. Growth parameters should be noted.
Because the abdominal examination may elicit discomfort, it is advisable to begin the examination with the head. Examination should focus on the mucous membranes to assess whether they are moist or dry. Nasal polyps; psoriasiform dermatitis around the eyes, nose, and mouth; and oral ulcerations should be noted.
Examination of the extremities focuses on skin turgor, capillary refill time, and presence of petechiae or purpura. Other forms of rash and signs of erythematous, swollen joints should be noted.
Abdominal examination focuses on distention, tenderness, and quality of bowel sounds (eg, high-pitched, normal, absent). Examination of the genitals focuses on presence of rashes and signs of anal fissures or ulcerative lesions.
Red flags
The following findings are of particular concern:
Interpretation of findings
Antibiotic-related, postinfectious, and anatomic-related causes of diarrhea are typically clear from the history. Determination of the time frame helps establish whether diarrhea is acute or chronic. Establishing the level of acuity is also important. Most cases of acute diarrhea have a viral etiology, are low acuity, and cause fever and nonbloody diarrhea. However, bacterial diarrhea can lead to serious consequences; manifestations include fever, bloody diarrhea, and possibly a petechial or purpuric rash.
Symptoms associated with chronic diarrhea can vary and those of different conditions can overlap. For example, Crohn's disease and celiac sprue can cause oral ulcerations, a number of conditions can cause rashes, and any condition can lead to a poor growth pattern. If the cause is unclear, further tests are done based on clinical findings (see Table 19: Approach to the Care of Normal Infants and Children: Some Causes of Diarrhea).
Testing
Testing is unnecessary in most cases of acute self-limited diarrhea. However, if the evaluation suggests an etiology other than viral gastroenteritis, testing should be directed by the suspected etiology (see Table 19: Approach to the Care of Normal Infants and Children: Some Causes of Diarrhea).
If dehydration is suspected, screening laboratory tests should be done (for electrolytes).
Treatment
Specific causes are treated (eg, gluten-free diet for children with celiac disease).
General treatment focuses on hydration, which can usually be done orally; IV hydration is rarely essential. (Caution: Antidiarrheal drugs [eg, loperamide] are not recommended for infants and young children.)
Rehydration
Oral rehydration solution (ORS) should contain complex carbohydrate or 75 mEq/L glucose and 75 mEq/L Na (total 245 mOsm/L solution). Sports drinks, sodas, juices, and similar drinks do not meet these criteria and should not be used. They generally have too little Na and too much carbohydrate to take advantage of Na/glucose cotransport, and the osmotic effect of the excess carbohydrate may result in additional fluid loss.
ORS is recommended by the WHO and is widely available in the US without a prescription. Premixed solutions are also available at most pharmacies and supermarkets.
Small, frequent amounts are used, starting with 5 mL q 5 min and increasing gradually as tolerated (see see Dehydration and Fluid Therapy in Children: Oral Rehydration). Generally, 50 mL/kg is given over 4 h for mild dehydration, and 100 mL/kg is given over 4 h for moderate dehydration. For each diarrheal stool, an additional 10 mL/kg (up to 240 mL) is given. After 4 h, the patient is reassessed. If signs of dehydration persist, the same volume is repeated.
Diet and nutrition: Children should eat an age-appropriate diet as soon as they have been rehydrated and are not vomiting. Infants may resume breast milk or formula.
For chronic diarrhea, adequate nutrition must be maintained, particularly of fat-soluble vitamins.
Key Points
Last full review/revision February 2010 by Eve R. Colson, MD; Rachel L. Chapman, MD; Melissa R. Held, MD
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