The different diagnostic approaches to IgE-mediated food allergies include medical history, skin prick testing, sIgE testing, and confirmation with an oral food challenge. A review study found that overdiagnosis of food allergies can have a significant and negative impact on the psychosocial and economic well-being of patients and their families.
Immunoglobulin-E (IgE)-mediated food allergies occur in response to proteins present in foods and may present as urticaria, stridor, abdominal pain, hypotension, and angioedema. The diagnostic practice in current use involves a detailed medical history followed by confirmatory tests. The appropriate use of diagnostic tests requires a thorough knowledge of predictive value, specificity, and sensitivity. In a recent review published in the journal Archives of Disease in Childhood, the authors describe different diagnostic and confirmatory tests for IgE-mediated food allergies.
Medical History
The current testing guidelines agree on the importance of medical history in the diagnosis of IgE-mediated food allergies. A proper medical history guides further testing to confirm the diagnosis. A medical history can be further supplemented with a physical examination.
Skin Prick and sIgE Diagnostic Tests
In the skin prick test, the antigen is introduced into the epidermis. A weal and flare reaction occurs when IgE antibodies are produced in response to a particular antigen. In the sIgE test, circulating IgE antibody levels are determined. This test can be associated with false-positive findings in some patients.
Oral Food Challenge for Confirmation of Food Allergy
An oral food challenge (OFC) can confirm the presence or absence of IgE-mediated food allergies in patients with a history relevant to the skin prick test and sIgE results. In OFC, a single or escalating dose of a suspected food is given to the patient, and the reactions are directly observed by a healthcare professional. OFC should be performed on a regular basis to assess the development of oral tolerance.
Tests Not Recommended for Food Allergies
Tests that are not recommended for the diagnosis of IgE-mediated food allergies include large panel screens and component-resolved testing for food allergies other than peanut allergy.
Interpretation of Diagnostic Test Results and Overtesting
It is imperative that physicians interpret and communicate whether the patient has confirmed IgE-mediated food allergy or sensitization to the food. Medical history, skin prick testing, and OFCs inform the diagnosis of IgE-mediated food allergy. The overtesting and overdiagnosis of food allergies must be avoided so as to prevent unnecessary stress and burden on the patients and their caregivers.
Source:
Lieberman, J., Muraro, A., & Blaiss, M. (2024). How to diagnose IgE-mediated food allergy. Archives of Disease in Childhood – Education and Practice. https://doi.org/10.1136/archdischild-2023-325938
