Discontinuation of specific IgE testing to food allergen mixes
Testing for specific IgE (previously known as RAST testing) to individual food allergens can support a diagnosis of food allergy in patients with clinical history suggestive of an immediate (IgE-mediated) allergic reaction. Specific IgE testing to food allergens is not recommended as a screening test for food allergies in the absence of a history of allergic reactions to those foods, or in patients with symptoms not suggestive of IgE-mediated food allergy, due to high rates of false positives.
Allergen-specific IgE tests to multiple food allergens in a single test (food allergen mixes) are no longer recommended by the Australasian Society of Clinical Immunology and Allergy as positive tests cannot identify the relevant food allergen and may be less sensitive than specific IgE tests to single food allergens.
Testing should only be performed when there is a history that suggests an immediate allergiv reaction to food, characterised by symptoms including acute onset urticaria, angioedema, vomiting and / or anaphylaxis, and testing should only be for the suspected food allergen/s. Positive food allergen mixes may lead to unnecessary and potentially harmful food restrictions.
Due to these recommendations, PathWest will no longer perform Staple Food Mix or Nut Mix specific IgE testing on routine requests from 1 May 2025. This change in practice has been endorsed by the Perth Children's Hospital Immunology Department. All requests for specific IgE testing should specify the individual food allergens that are suspected to have caused an immediate IgE-mediated allergic reaction. If an individual food allergen is not specified on the request form, the patient's sample will be stored pending confirmation from the requesting clinician of which food allergens are to be tested.
PathWest will continue to provide a comprehensive repertoire of allergen specific IgE testing to support clinicians in the diagnosis of food allergy.
Contact for more information
PathWest Immunology Laboratory at QEII
E:QEImmunology.PathWest@health.wa.gov.au
T: (08)6383 4306