Allergy testing: skin prick tests and specific IgE
What skin prick tests and serum specific IgE measure, the 3 mm and 0.35 kU/L thresholds, controls and medicines that blunt the skin, sensitisation versus allergy, component (recombinant) allergens for peanut, nuts, wheat and venom, and when a result changes management.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Both tests detect allergen-specific IgE. Skin prick tests (SPT) detect IgE bound to skin mast cells; serum specific IgE (sIgE, once called RAST) detects free IgE in blood.
- A positive result shows sensitisation. It means allergy only when it fits a history of reactions on exposure. ASCIA advises against testing without a matching history.
- SPT is ASCIA's preferred first test for most IgE-mediated disease: cheap, results in 20 minutes, slightly more sensitive. sIgE is used when the skin can't be tested or drugs can't be stopped.
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Sources
- ASCIA Skin Prick Testing Guide for the Diagnosis of Allergic DiseaseAU/NZASCIA (Australasian Society of Clinical Immunology and Allergy), 2025 (content updated 2024, format 2025)
- ASCIA Position Paper: Laboratory investigation of allergic diseasesAU/NZASCIA, content 2020, format updated 2025
- ASCIA Allergy testing (patient information), including unorthodox tests not recommendedAU/NZASCIA, 2024
- ASCIA Guidelines: Adult penicillin allergy management, 2026 updateAU/NZASCIA, National Allergy Council and National Allergy Centre of Excellence, October 2026
- Dramburg S et al. EAACI Molecular Allergology User's Guide 2.0. Pediatr Allergy Immunol 2023;34 Suppl 28:e13854European Academy of Allergy and Clinical Immunology, 2023
- RCPA Manual: allergen specific IgEAU/NZRoyal College of Pathologists of Australasia, online edition, accessed November 2026
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Turnstile bot check on sign-in and signed-out feedback