Non-IgE Mediated Gastrointestinal Disorders
These disorders affect mainly young infants. Symptoms tend to be more subacute and/or chronic and are commonly isolated to the GI tract. Affected infants usually present with a characteristic constellation of clinical and demographic features that are consistent with well-described disorders, including food protein-induced proctocolitis, food protein-induced enteropathy and food protein-induced enterocolitis (Table 1). The causal food is usually cow's milk, but can also occur with soy-based formula and solid foods such as rice, cereals, eggs and poultry. This type of food allergy should be considered in any infant presenting in the first year with chronic diarrhea associated with blood and/or mucous in the stool, and failure to thrive. Affected infants commonly have normal serum IgE levels and negative SPT. An investigational panel of tests including blood tests, stool analysis for occult blood, colonoscopy and biopsy may be required to confirm the diagnosis. Most of these infants (90%) will become tolerant to cows' milk by 1 year of age.[10,23]
Food Protein-induced Proctocolitis
This disorder is considered a form of eosinophilic GI disorder, but it only appears to involve a non-IgE mediated mechanism. It generally presents in the first few months of life because of food proteins passed through the maternal breast milk (~50% of infants) or in cow's milk-or soy-based formulas. Apart from gross or microscopic blood in the stools, affected infants appear healthy and grow well. The diagnosis of this disorder requires colonoscopy in order to rule out other causes of rectal bleeding such as anatomic abnormalities, rectal ulcers or polyps. Lesions are confined to the distal large bowel and consist of mucosal edema, with clusters of eosinophilic infiltration in the epithelium and lamina propria of the sigmoid colon and the rectum. Symptoms usually clear by 1 year of age.[23,24]
Food Protein-induced Enterocolitis Syndrome
This syndrome is most commonly seen in infants during the first 3 months of life, but might be delayed in breastfed babies. Symptoms are most commonly provoked by the ingestion of cow's milk or soy protein-based formulas, but might be caused by other cereal grains in older infants.[2,5] It is characterized by severe symptoms of prolonged projectile vomiting that develops within a few hours after feeding. During chronic or intermittent ingestion of the causal food protein, infants may experience such severe vomiting and diarrhea that dehydration, lethargy, acidosis and methemoglobinemia may result, and infants may seem septic with high peripheral leukocyte counts. The diagnosis of such cases is usually confirmed by disappearance of symptoms after a period of elimination of the causal food and the positive oral challenge that results in severe vomiting and diarrhea. Caution is needed when performing oral challenge since approximately 20% of reactions lead to shock. The mechanism underlying this disorder seems to involve a milk-specific T-cell response with excessive production of the cytokine TNF-α that may account for some of the systemic symptoms.
Food Protein-induced Enteropathy
Food protein-induced enteropathy (excluding celiac disease) usually presents in the first several months of life with nonbloody diarrhea, steatorrhea, malabsorption and failure to thrive (Figure 2).[2,9,26] Protein-losing enteropathy may lead to edema, abdominal distension and anemia.
The differential diagnosis must consider other causes of enteropathy including infection, metabolic, lymphangiectasia and celiac disease. Allergenic foods of this disorder include cow's milk, soy, cereal grains, egg and seafood. Diagnosis is based on the combined findings of endoscopy, biopsy, allergen elimination and challenge. Biopsy shows small bowel villous injury, increased crypt length, intraepithelial lymphocytes and few eosinophils. Unlike celiac disease, this enteropathy is self-limited as it usually resolves, in most cases, by of 2 years of age and there is no risk of malignancy.
Pediatr Health. 2009;3(3):217-229. © 2009 Future Medicine Ltd.
Cite this: Gastrointestinal Manifestations of Food Allergy - Medscape - Jun 01, 2009.