Approach to diet-induced diarrhea in children >6 months of age

tTg: tissue transglutaminase; IgA: immunoglobulin A; IBD: inflammatory bowel disease.
* tTg-IgA is a sensitive and specific screening test for celiac disease if performed on a gluten-containing diet; some clinicians measure total IgA at the same time to exclude IgA deficiency.
¶ Clinical signs/symptoms suggesting a possible immunodeficiency include a history of infections and persistent or recurrent infectious diarrhea.
Δ Postinfectious diarrhea is often mediated by lactase deficiency but may involve more generalized malabsorption. Symptoms often respond to avoiding lactose and highly concentrated sugars and gradually improve over weeks to months.
◊ In infants who are otherwise healthy, a common cause of loose stools (typically with gross blood) is food protein-induced proctocolitis of infancy, sometimes known as food-protein intolerance. The most common food triggers are cow's milk, egg, or soy. Symptoms gradually improve when the offending protein is rigorously eliminated from the diet. Refer to relevant UpToDate content.
§ Food allergy or food protein-induced enteropathy have a wide range of manifestations, including timing of onset (immediate hypersensitivity versus persistent symptoms), severity, and associated symptoms (vomiting, hematochezia). Refer to an allergy specialist if symptoms are severe or if there is strong suspicion of an allergic mechanism.
¥ In toddlers and young children, mild or intermittent diarrhea that is otherwise unexplained is considered functional but may be exacerbated by excessive fructose or sorbitol consumption.