Pathogenesis: a cell-mediated immune reaction, not IgE-mediated. The reaction is probably related to the release of cytokines.
Clinical features:
(1) The onset is usually within a few weeks of birth.
(2) The infant presents with:
(2a) severe vomiting
(2b) diarrhea, which can be bloody
(2c) failure to thrive.
(3) Severely affected infants may
(3a) become ketotic
(3b) develop methemoglobinemia and/or
(3c) become hypotensive with shock
(4) The patient is usually sensitive to both cow's milk and soy protein.
(5) Some infants show a sensitivity to one or more additional sources of dietary protein (rice, oat, barley, sweet potato, squash, peas, chicken, turkey, other).
(6) The child does fine if the triggering foods are eliminated from the diet.
(7) The intolerance to the food protein tends to disappear with age, often by 3 years of age.
Laboratory features:
(1) There is an elevation of the absolute neutrophil count following exposure to a triggering protein.
(2) Colon biopsies show a chronic enterocolitis with cryptitis and crypt abscesses.
The diagnosis requires exclusion of other causes of enterocolitis.
