Food Protein-Induced Enterocolitis Syndrome (FPIES) is a severe systemic response to food protein that typically occurs 1 to 4 hours after the ingestion of the causative food and frequently develops in the first few years of life. In the severe form, patients will vomit until dehydration and until a shock-like state, which occurs in 15% of patients. FPIES occurs primarily in young infants, but can exist in older children and adults.
In the severe form, symptoms include vomiting, diarrhea, and acidosis. Laboratory studies during the acute episode shows an elevated white blood cell count with a left shift and elevated platelet count and methemoglobinemia. Endoscopy may reveal a mixed Eosinophilic and neutrophilic infiltrate but is not required to make the diagnosis. The exact mechanism is unclear, but it is hypothesized to be a T cell driven disorder.
There is a variant of FPIES and it manifests as chronic emesis, diarrhea, and failure to thrive. Upon re-exposure to the offending food after a period of elimination, a subacute syndrome can present with repetitive emesis and dehydration.
Milk and soy protein are the most common trigger foods, but other foods have been reported including rice, oat, chicken, peanut, potato, fish, and egg. A similar condition also has been reported in adults, most often related to crustacean shellfish ingestion. There are also cases of FPIES being transmitted through foods in breast milk in rare occasions.
Diagnosis is primarily based on history as specific IgE and skin prick tests are typically negative. In one study, atopy patch tests was found to be helpful.
The prevalence of FPIES in a population study in Israel was 0.3%. Studies have found 90% of the children outgrew it by 3 years of age.