Definitive diagnosis of nut allergy
- Dr Armstrong.
- Accepted 24 September 1998
Abstract
OBJECTIVE To compare findings of tests for nut allergy in children.
DESIGN Retrospective survey of a clinical practice protocol.
SETTING Children’s hospital paediatric outpatient clinic.
SUBJECTS 96 children referred by general practitioners and accident and emergency doctors over 27 months (1994–96).
MAIN OUTCOME MEASURES Allergic manifestations (generalised urticarial rash, facial swelling, bronchospasm, anaphylactic shock, vomiting on three occasions) related to specific nut IgE concentrations and following touch, skin prick, or oral ingestion of nuts.
RESULTS 16 children from a sample of 51 who were tested for nut allergy had no reaction to an oral challenge. Positive IgE against peanuts was found in nine of these 16 children.
CONCLUSIONS Skin prick testing and IgE measured by radioallergosorbent testing are inadequate tests for nut allergy. The definitive diagnostic test for nut allergy in the hospital setting is direct oral challenge.
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Definitive diagnosis of nut allergy is important because of anxiety, lifestyle, and resource implications
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A history of apparent allergic reaction to nuts is usually inadequate for diagnosis
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IgE titres and skin tests are limited by false positive and false negative results
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Oral challenge is the practical definitive test of nut allergy
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When allergy to one type of nut is confirmed, allergy to other nuts should be considered
