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Clinical features and blood tests are clues to diagnosing FPIES

Published online: October 25, 2018

Food protein-induced enterocolitis syndrome (FPIES) is an uncommon food allergic disease of infants. The immunological mechanisms behind this disorder are poorly understood.  Diagnosis is based on a characteristic constellation of symptoms with profuse vomiting occurring 1 to 4 hours after ingestion of the trigger food as the hallmark symptom, which may be accompanied by pallor, floppiness, lethargy, hypotension, and/or diarrhea.  Although often self-resolving, these symptoms are alarming; and for the busy emergency doctor, more common pediatric diseases with similar presentations must be excluded.  As such, FPIES presentations are frequently missed or misdiagnosed, with children presenting multiple times to the emergency department before a diagnosis is made.

In a recent study published in The Journal of Allergy and Clinical Immunology: In Practice, Lee et al. compared the clinical features, vital signs and routine laboratory blood tests of three disease cohorts with similar emergency presentations- FPIES, bacterial sepsis, and gastroenteritis- in order to identify clues to aid in the differentiation and diagnosis of FPIES from its mimics.  The retrospective study was conducted at a major pediatric tertiary hospital emergency department capturing 181 FPIES presentations within the last 20 years.  These were compared to 36 sepsis and 55 gastroenteritis presentations within the last 2 years.

Of the clinical features examined, lethargy, floppiness and pallor accompanying vomiting were more common in FPIES than sepsis or gastroenteritis, with 62% of all FPIES presentations involving all four symptoms.  Diarrhea and bloody stools were more common in gastroenteritis than either FPIES or sepsis.  Children with severe presentations involving abnormal vital signs of fever and tachycardia were more likely to be diagnosed with sepsis than FPIES.  Low blood pressure was not a prominent feature of FPIES presentations (4%) within the study.  Of the routine blood tests performed in the emergency department, a normal C-reactive protein (CRP, a systemic marker of inflammation) was the predominant feature in FPIES presentations.  In comparison, CRP was 3 times more likely to be elevated in sepsis or gastroenteritis.  Median CRP levels for sepsis and gastroenteritis were 27 and 14 times higher than in FPIES, respectively.  Normal electrolytes, elevated platelet count, low mean platelet volume, and an elevated albumin/globulin protein ratio were also observed more commonly in FPIES presentations.

This study shows that associated symptoms and signs on clinical history and examination remain crucial to the diagnosis of FPIES.  Characteristic clues on presentation of the young vomiting child which may indicate a possible diagnosis of FPIES include a history of a trigger food, associated symptoms of lethargy, floppiness, pallor without a fever, and on examination normal vital signs.  Importantly, of the routine blood tests performed in emergency, this study demonstrated that a highly elevated CRP is not a feature of FPIES, and so alternative diagnoses must be considered.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.