Volume requirements will vary with the number of specific IgE assays requested.
Absolute minimum volumes for paediatric samples are 500uL blood for one allergen and 100uL for each additional allergen.
Tests performed on Monday, Tuesday and Friday
Clinical history is vital in the interpretation of all allergy test results. Allergen specific IgE can be detected in vivo using skin prick or intradermal tests and in vitro using serum specific IgE (sIgE). These in vitro tests may also be referred to as an EAST although some still refer to them as a RAST, a historical laboratory methodology for detecting sIgE which is no longer in routine diagnostic use. In general, sIgE tests are more expensive than skin tests.
In the past the lower limit of detectable serum sIgE was 0.35 kUA/L, however serum specific IgE to individual allergens can now be reliably detected down to 0.1 kUA/L. There is no positive or negative clinical cut off for serum sIgE values. The clinical relevance of sIgE at different levels depends on the clinical history, the allergen, age of the patient, total IgE and the interval since the clinical reaction. Undetectable sIgE does not exclude clinically relevant allergy and detectable sIgE does not confirm a patient is allergic in the absence of the appropriate clinical history.
We do not recommend using sIgE as a screening tool for allergy. Several hundred allergens are available for testing and targeted testing in patients, who give a good clinical history, will maximize the positive predictive value of these tests. Allergen mixes have a lower analytical sensitivity than single allergens. We ask that you specifically nominate which allergens you would like tested.
Testing for specific IgE is not recommended in patients where symptoms are not usually associated with IgE antibodies, e.g. chronic spontaneous urticaria, irritable bowel syndrome, migraines etc.
The most common allergens are environmental (aeroallergens) or foods. Drug, venom and component resolved sIgE testing should only be requested by a clinician experienced in the treatment and diagnosis of severe allergic disease or following their recommendation.
Please call via Lablink to discuss with the immunopathology team or email immunology@adhb.govt.nz if you have further questions regarding your allergy test request.
Uncertainty of Measurement: 18%
References:
Additional Information:
The Immunopathology team can be reached via email: immunology@adhb.govt.nz or via Lablink (09) 307 4949 ext 22000:
- Professor Rohan Ameratunga (Immunopathologist)
- Dr Maia Brewerton (Immunopathologist)
- Dr Miriam Hurst (Immunopathologist)