Diarrhea

Frequent loose bowel movements (4 to 6/day) may occur in normal infants; they are of no concern unless anorexia, vomiting, weight loss, failure to gain weight, or passage of blood also occurs. Breastfed infants tend to have frequent bowel movements, especially if they are not receiving solid food. The significance of diarrhea in a child at any age differs if it is acute (< 2 wk) or chronic (> 2 wk).

Etiology
Acute diarrhea is most likely infectious, especially if onset is sudden or accompanied by vomiting, bloody stools, fever, anorexia, or listlessness. Diagnosis is clinical, and treatment is supportive until the condition resolves spontaneously.

Chronic diarrhea is usually more significant. Causes include gluten-induced enteropathy, cystic fibrosis, sugar malabsorption, and allergic gastroenteropathy. Inflammatory bowel disease and some infections (eg, with Giardia) can also cause chronic diarrhea.

With gluten-induced enteropathy (celiac sprue), the gluten fraction of wheat protein causes intestinal mucosal damage and malabsorption of dietary fats, resulting in malnutrition, anorexia, and bulky, foul-smelling stools. The change in stools starts when wheat and other gluten-containing foods are added.


With cystic fibrosis, pancreatic insufficiency results in trypsin and lipase deficits, causing high fecal losses of protein and fats with consequent malnutrition and growth retardation. The stool is voluminous and often foul-smelling. Children who have cystic fibrosis often have respiratory problems and growth failure.


With sugar malabsorption, intestinal mucosal enzymes, such as lactase, which splits lactose to galactose and glucose, may be congenitally absent or temporarily deficient secondary to GI infection. Improvement after eliminating lactose (or other carbohydrates) from the diet or after substituting a lactose-free formula strongly suggests the diagnosis.


With allergic gastroenteropathy, cow's milk protein may cause diarrhea, often with vomiting and blood in the stools, but intolerance to the carbohydrate fraction of the ingested food should be suspected also. Symptoms often abate promptly when soy formula is substituted for cow's milk and return if cow's milk is reintroduced. Some infants intolerant of cow's milk are also intolerant of soy, so a formula that has had the protein pre-digested and does not contain the offending disaccharide may be needed. Spontaneous improvement usually occurs toward the end of the 1st yr.


Evaluation


History: History focuses on the quality and frequency of stools as well as accompanying signs and symptoms. Reports of vomiting or fever suggest GI infection. An accurate dietary history is critical. Reports of diarrhea beginning with the introduction of wheat cereal suggest celiac disease. Reports of variation in the stool pattern with certain elements of the diet suggest dietary intolerance. The persistent presence of blood in the stool mandates a careful search for more serious infection or GI disorder.

Physical examination: Examination focuses on overall appearance and signs of dehydration, growth parameters, and abdominal findings; poor growth suggests more serious disorders. Pulmonary status is also evaluated in children in whom cystic fibrosis is suspected.

Testing: Tests are ordered if history and examination suggest a chronic condition. Tests include electrolyte levels if there is dehydration; sweat Cl and Na levels for cystic fibrosis; cultures for viruses, bacteria, or parasites when infection appears to be present; and stool pH for disaccharide intolerance. Levels of certain antibodies are associated with celiac disease. Dietary manipulations can be diagnostic as well as therapeutic.

Treatment


Supportive care for acute diarrhea consists primarily of providing adequate oral (or rarely IV) rehydration. Antimotility agents (eg, loperamide: IMODIUM) are generally not recommended for infants and young children.


For chronic diarrhea, adequate nutrition must be maintained, particularly of fat-soluble vitamins. Specific treatments are indicated for certain causes (eg, gluten-free diet for those with celiac disease).