Peanut nut and
tree nut allergy are characterised by
IgE mediated reactions to
nut proteins.
Nut allergy is a global disease. Limited epidemiological data suggest varying prevalence in different geographical areas. Primary
nut allergy affects over 2% of children and 0.5% of adults in the UK. Infants with severe
eczema and/or
egg allergy have a higher risk of
peanut allergy. Primary
nut allergy presents most commonly in the first five years of life, often after the first known ingestion with typical rapid onset
IgE-mediated symptoms. The clinical diagnosis of primary
nut allergy can be made by the combination of a typical clinical presentation and evidence of nut specifc
IgE shown by a positive skin prick test (SPT) or specific
IgE (sIgE) test. Pollen food syndrome is a distinct disorder, usually mild, with oral/pharyngeal symptoms, in the context of
hay fever or pollen sensitisation, which can be triggered by nuts. It can usually be distinguish clinically from primary
nut allergy. The magnitude of a SPT or sIgE relates to the probability of clinical
allergy, but does not relate to clinical severity. SPT of ≥ 8 mm or sIgE ≥ 15 KU/L to peanut is highly predictive of clinical
allergy. Cut off values are not available for tree nuts. Test results must be interpreted in the context of the clinical history. Diagnostic food challenges are usually not necessary but may be used to confirm or refute a conflicting history and test result. As
nut allergy is likely to be a long-lived disease, nut avoidance advice is the cornerstone of management. Patients should be provided with a comprehensive management plan including avoidance advice, patient specific emergency medication and an
emergency treatment plan and training in administration of emergency medication. Regular re-training is required.