Diarrhea is frequent loose or watery bowel movements that deviate from a child’s normal pattern.
Diarrhea may be accompanied by anorexia, vomiting, acute weight loss, abdominal pain, 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 diarrhea and dehydration cause about 1.5 to 2.5 million deaths/year worldwide. It accounts for about 9% of hospitalizations in the US among children < 5 years of age.
Diarrhea in adults is discussed elsewhere.
Pathophysiology of Diarrhea in Children
Mechanisms of diarrhea may include the following:
Osmotic
Secretory
Inflammatory
Malabsorptive
Osmotic diarrhea results from the presence of nonabsorbable solutes in the gastrointestinal 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 chloride 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 disease, ulcerative colitis). The resultant outpouring of plasma, serum proteins, blood, and mucus 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 pancreatic insufficiency and short bowel syndrome and conditions that speed up transit time cause diarrhea due to decreased absorption.
Etiology of Diarrhea in Children
The causes and significance of diarrhea ( see Table: Some Causes of Diarrhea) differ depending on whether it is acute (< 2 weeks) or chronic (> 2 weeks). Most cases of diarrhea are acute.
Acute diarrhea usually is caused by
Antibiotic use
Food poisoning
Most gastroenteritis is caused by a virus; however, any enteric pathogen can cause acute diarrhea.
Chronic diarrhea usually is caused by
Dietary factors
Infection
Chronic diarrhea can also be caused by anatomic disorders and disorders that interfere with absorption or digestion.
Evaluation of Diarrhea in Children
History
History of present illness
Review of systems should seek symptoms of both complications and causes of diarrhea. 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); and arthritis, skin lesions, and anal fissures (inflammatory bowel disease).
Past medical history should assess known causative disorders (eg, immunocompromise, cystic fibrosis, celiac disease, inflammatory bowel disease) in the patient and family members.
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 the presence of petechiae, purpura, other skin lesions (eg, erythema nodosum, pyoderma gangrenosum), rashes, and erythematous, swollen joints.
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:
Tachycardia, hypotension, and lethargy (significant dehydration)
Bloody stools
Bilious vomiting
Extreme abdominal tenderness and/or distention
Petechiae and/or pallor
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 disease and celiac disease 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: 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: Some Causes of Diarrhea).
Treatment of Diarrhea in Children
Specific causes of diarrhea 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
Rehydration
Oral rehydration solution (ORS) should contain complex carbohydrate or 2% glucose and 50 to 90 mEq/L (50 to 90 mmol/L) sodium. Sports drinks, sodas, juices, and similar drinks do not meet these criteria and should not be used. They generally have too little sodium and too much carbohydrate to take advantage of sodium/glucose cotransport, and the osmotic effect of the excess carbohydrate may result in additional fluid loss.
ORS is recommended by the World Health Organization and is widely available in the US without a prescription. Premixed solutions are also available at most pharmacies and supermarkets.
If the child is also vomiting, small, frequent amounts are used, starting with 5 mL every 5 minutes and increasing gradually as tolerated ( see heading on page Oral Rehydration). If the child is not vomiting, the initial amount is not restricted. In either case, generally 50 mL/kg is given over 4 hours for mild dehydration, and 100 mL/kg is given over 4 hours for moderate dehydration. For each diarrheal stool, an additional 10 mL/kg (up to 240 mL) is given. After 4 hours, the patient is reassessed. If signs of dehydration persist, the same volume is repeated.
Diet and nutrition
Children with an acute diarrheal illness 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 nonspecific diarrhea of childhood (toddler's diarrhea), dietary fat and fiber should be increased, and fluid intake (especially fruit juices) should be decreased.
For other causes of chronic diarrhea, adequate nutrition must be maintained, particularly of fat-soluble vitamins.
Key Points
Diarrhea is a common pediatric concern.
Gastroenteritis is the most common cause.
Testing is rarely necessary in children with acute diarrheal illnesses.
Dehydration is likely if diarrhea is severe or prolonged.
Oral rehydration is effective in most cases.
