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Chronic Nonspecific Diarrhea

Michael A. Davis, MD

 

Diarrhea is considered chronic when it persists for longer than 3 weeks. Chronic nonspecific diarrhea (CNSD) presents in toddlers between 18 months and 3 years of age, with frequent, large, watery stools in the absence of physical or laboratory signs of malabsorption or infection and without effect on growth or development. Children have 3 to 6 large, watery bowel movements daily. The diarrhea spontaneously resolves in 90% of children between by 40 months of age, often coincidentally with toilet training.

Pathogenesis

Factors Causing CNSD

Excess fluid intake

Carbohydrate malabsorption from excessive juice ingestion

Disordered intestinal motility

Excessive fecal bile acids

Low fat intake

Fluid intake exceeds the absorptive capacity of the intestinal tract. Malabsorption of carbohydrates (sucrose, fructose, sorbitol) in fruit juices contributes to CNSD.

Presentation. CNSD presents between 18 months and 3 years, with 3-6 large, loose, watery stools per day for more than 3 weeks. Stools may have been loose throughout infancy, especially in breast fed infants.

Stools may have been formed until a recent episode of gastroenteritis or other acute illness; or the stools may have become diarrheal without an antecedent illness.

Stooling is most frequent in the morning and does not occur during sleep. There is an absence of nausea, vomiting, abdominal pain, flatulence, blood, fever, anorexia, weight loss, or poor growth.

Clinical Evaluation of Chronic Nonspecific Diarrhea

The current number and type of stools should be determined. A diet history should determine the total calories, fat, milk and juice consumed daily, the history should assess prior trials of elimination diets or currently eliminated foods.

The timing of introduction of foods into the diet relative to the onset of diarrhea, and a 3-day diet history should be assessed. Usage of antibiotics, vitamins, iron, and medications should be sought.

A family history of irritable bowel syndrome, celiac disease, inflammatory bowel disease, infectious diarrhea, or food allergies should be sought.

Physical Examination

Growth chart plotting of weight, height, and head circumference are essential. Children who have CNSD should continue to grow normally; deviation from the growth chart or a downward trend suggests inadequate caloric intake or a disease other than CNSD.

Signs of malnutrition or malabsorption include lack of subcutaneous fat, eczematoid rash (from essential fatty acid deficiency), glossitis, easy bruising, or hyporeflexia.

Laboratory Tests

A fresh stool specimen is tested for neutral fat with an oil stain, pH and reducing substances, occult blood, and Giardia antigen. Neutral fat >40 globules per high power microscopic field suggest pancreatic insufficiency.

Fecal pH and reducing substances will reveal carbohydrate malabsorption if the pH is less than 5.5 or if reducing substances are greater than 1+.

Occult fecal blood is inconsistent with CNSD unless there is a perianal rash.

Giardia and Cryptosporidium are common and should be excluded with 3 stool samples for ova and parasites.

Stool Evaluation

Test

Result

Disease

pH

<5.5

Carbohydrate malabsorption

Reducing substances

>1+

Neutral fat

>40 globules/high power field

Pancreatic insufficiency

Occult blood

Positive

Enteritis or colitis

Giardia antigen

Positive

Giardiasis

Ova and parasites

Positive

Giardiasis, cryptosporidiosis

Differential Diagnosis

The differential diagnosis of chronic diarrhea in the 6-to 36-month-old child also includes disaccharidase deficiency, protein intolerance, enteric infection, and malabsorption.

Lactase deficiency

Lactase deficiency may cause diarrhea associated with milk ingestion. In toddlers it is usually is caused by viral gastroenteritis.

Lactose intolerance caused by acute viral gastroenteritis usually resolves within 10-14 days.

Congenital lactase deficiency is extremely rare and symptoms are present from birth if an infant is fed human milk or a lactose-containing formula.

Genetically acquired lactase deficiency is common, but it usually is not symptomatic before 5 years of age.

Congenital sucrase-isomaltase deficiency also is rare, producing symptoms when sucrose-containing formula or foods are introduced.

Disaccharidase deficiency can be confirmed by eliminating the specific carbohydrate or by breath hydrogen analysis after ingestion of lactose or sucrose.

Milk-induced colitis occurs in infants younger than 1 year of age who typically appear healthy but lose blood in their stool after ingesting milk protein. In contrast, infants who have milk-induced enterocolitis are younger, less than 3 months of age. These infants may be severely ill with bloody diarrhea, hypoproteinemia, and growth failure. Children who have protein allergies tend to come from families that have allergic histories; affected children may have other atopic disorders (eczema, allergic rhinitis, asthma).

Giardia or Cryptosporidium enteric infections are commonly transmitted by asymptomatic carriers at child care centers. Foul-smelling diarrhea usually is associated with abdominal distension and flatus. Diagnosis is confirmed by finding Giardia antigen in stool or three stools for ova and parasites, with special stains for Cryptosporidium.

Malabsorption presents with chronic diarrhea, weight loss, poor appetite, weakness and decreased activity, bloating and flatulence, abdominal pain, or chronic vomiting. The most common causes are cystic fibrosis and celiac disease. Chronic diarrhea and failure to thrive warrants a sweat test. Screening for celiac disease consists of a D-xylose absorption test and a serum celiac disease panel (antigliadin, antiendomysial, and antireticulin antibodies). Celiac disease must be confirmed by intestinal biopsy.

Management of CNSD

Fluid intake is gradually reduced to less than 100 mL/kg/day. Water is substituted for juice to reduce the child's interest in drinking. Switching from the bottle to the cup also decreases fluid intake.

Fat intake is increased to 4 g/kg/day by adding whole milk to the diet. If lactose intolerance is present, low-lactose milk can be used or lactase drops can be added to milk.

Butter, margarine, or vegetable oil are liberally added to foods for children less than 2 years of age.

Dietary fiber can be increased by consumption of fresh fruits and vegetables or by the addition of bran to cereal, main dishes or cookies, or by giving psyllium or Citrucel (1 to 2 tsp/day).

Removing dairy products to avoid lactose malabsorption may leave the child's diet with insufficient calories. Gluten-free diets and diets that restrict other proteins, such as cow milk protein, also should not be used without solid evidence of celiac disease, protein intolerance, or allergy.