We recently published a study on FPIES in the Journal of Allergy and Clinical Immunology in Practice (https://www.jaci-inpractice.org/article/S2213-2198(18)30677-9/abstract). This was conducted at the Children’s Hospital Westmead, Sydney, and we compared the clinical and laboratory features of FPIES with two conditions it is frequently misdiagnosed as – sepsis and gastroenteritis.
The main findings were infants with FPIES were more likely to present without fever but with lethargy, floppiness, pallor and more likely to recover quickly. Infants with FPIES also often presented with a normal C-reactive protein (CRP) blood level.
We concluded in the young vomiting child, lethargy, floppiness, pallor without fever, a normal CRP and recovery (usually within 4-6 hours) should alert clinicians to a possible diagnosis of FPIES. A highly elevated CRP is not a feature of FPIES, and in such cases an alternative diagnosis must be considered.