Diagnosis and Testing

Increases in Adulthood

FPIES was previously thought to only affect infants and young children, but it has now been increasingly recognized that FPIES can occur in adulthood. FPIES in adults is more common in females and is most often caused by seafood, although other foods, such as cow’s milk/dairy, egg, and wheat are being reported. The acute gastrointestinal symptoms of FPIES in adults include severe abdominal pain, cramping, severe nausea, vomiting and  / or diarrhea that start within 1-4 hours following food ingestion. However, it is important to recognize that 25-40% of adult FPIES patients may not present with vomiting. Diagnosis in adults is frequently delayed; affected individuals experience repeated reactions before FPIES is considered. This delayed diagnosis can be attributed to poor awareness among the physicians and lack of the specific diagnostic criteria that accurately capture the adult FPIES presentation. Although the 2017 International Consensus Guidelines for FPIES proposed  diagnostic criteria, these criteria are more relevant to younger  patients experiencing FPIES, in whom repetitive vomiting is the cardinal feature. Since up to 40% of adults with FPIES do not experience vomiting, the 2017 Guidelines do not adequately capture this subset of patients. Thus, FPIES diagnosis should be considered for an adult patient who present with gastrointestinal symptoms within 1-4 hours following the specific food allergen ingestion on more than one occasion, with alternative etiologies carefully excluded. Future guidelines should highlight the differences between pediatric and adult patients and propose formal diagnostic criteria for adults.

A diagnosis of FPIES is usually made by clinical history and recognition of the symptoms pattern. However, a physician supervised  oral food challenge may be necessary to confirm the diagnosis, identify the offending food  or determine the natural resolution of FPIES. FPIES is a non-IgE mediated food allergy, thus percutaneous (prick) skin testing or IgE blood allergy testing is usually negative and not helpful for confirmation of FPIES diagnosis. However, in a subtype of FPIES known as atypical FPIES the patient  presents with classic symptoms consistent with FPIES and has positive skin and/or blood test to the FPIES trigger in question. In children, some of those with atypical FPIES may over time change (convert) to a classic food allergy with symptoms starting soon after food ingestion and involving skin and or lungs, in addition to gut. This conversion is more common in children who in addition to FPIES have other allergic disorders, including atopic dermatitis, asthma or other IgE-mediated food allergies. The risk of conversion from having an FPIES reaction to an IgE-mediated “immediate” reaction is not well known in adults.

Skin testing or blood testing to the FPIES food trigger will allow your practitioner to determine if you have “atypical” FPIES and  this will help determine how to approach the oral food challenge when the time comes to assess is FPIES has resolved with time.

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