Diagnosis and Testing

Diagnosis of FPIES in Children
Food Protein-Induced Enterocolitis Syndrome (FPIES) affects primarily young children, particularly during infancy with the early introduction of additional foods. FPIES is an abnormal immune response to an ingested food, resulting in gastrointestinal inflammation. The quantity of food that provokes symptoms has varied widely, reflecting the degree of hypersensitivity of individual patients. In some infants, the symptoms were provoked by very small food quantities, even traces of food that touched the mouth.


The symptoms of FPIES are primarily severe vomiting and diarrhea that can resemble acute gastrointestinal infection or food poisoning. The child may look very ill and dehydrated, resembling allergic anaphylactic shock or acute systemic infection.

The first episode usually occurs acutely within a couple of hours of ingestion but may be delayed for several hours, and it progresses rapidly in an alarming manner. A typical episode comprises repetitive projectile vomiting, pallor, followed by diarrhea, leading to lethargy and dehydration. Watery diarrhea follows in a few hours and may contain some blood. Rehydration results in rapid improvement though complete clinical resolution may take two to three days. In mild to moderate cases, frequent exposure to the causative food leads to chronic symptoms, irritability, and poor weight gain.

Causative Foods
Cow’s milk (or formula) and soy milk are the most common causes of FPIES in infants. In older children, rice, potato, and egg are the most common, but any food may cause FPIES.

The diagnosis of FPIES is based primarily on a convincing medical history of typical symptoms and progression, as described above, in the absence of fever or suspected food poisoning. Often, other possible causes of the symptoms are considered, including local or systemic infection, metabolic diseases, and gastrointestinal disorders. The causative food may not be identified until more than one episode happens.

Laboratory Findings
Laboratory tests are useful in evaluating the effects of the disease or in investigating for other diseases that can mimic FPIES. Acute episodes are associated with increased white blood cells, and the blood chemistry test may reflect dehydration or electrolyte imbalance. Chronic FPIES is associated with increased lymphocytes and eosinophils and sometimes decreased serum proteins. Typically, laboratory findings normalize and clinical improvement is seen within 48 hours of avoiding the causative food.

Unlike common allergic diseases, allergy skin tests or blood testing are not helpful because FPIES has a different underlying mechanism. Definite identification of the causative food would require performing titrated oral challenge with each suspected food. This test carries the risk of inducing an acute episode and should be planned and performed by an experienced specialist. The patient should be kept under observation for at least four hours. A blood cell count is drawn before the challenge and when symptoms appear or before discharge. For safety reasons, the test is usually avoided and the suspected foods are strictly eliminated. Recurrence of episodes would narrow down the causative food.

Once the culprit food is identified, strict avoidance should be followed. The result of accidental exposures might obviate the need for intentional challenge testing.

Provided by the I-FPIES Medical Advisory Board

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