Biomarker: F017-IgE Hazelnut (Filbert)

Overview

F017-IgE Hazelnut measures immunoglobulin E (IgE) antibodies in blood that specifically recognize hazelnut proteins. IgE participates in immediate allergic reactions by activating mast cells and basophils after allergen exposure. A detectable or elevated result indicates sensitization to hazelnut, but it does not by itself confirm clinical allergy, predict reaction severity, or establish a safe amount of hazelnut. The test is clinically useful as part of a history-guided evaluation of suspected IgE-mediated hazelnut allergy and may help determine whether component-resolved testing or a medically supervised oral food challenge is appropriate.

Clinical Use Cases

Support evaluation of suspected immediate hypersensitivity reactions after hazelnut exposure, including urticaria, angioedema, wheezing, vomiting, or anaphylaxis.
Identify sensitization to hazelnut when skin testing is unsuitable or cannot be performed.
Assess hazelnut sensitization alongside clinical history, physical examination, and other allergy tests.
Help distinguish possible pollen-related cross-sensitization from primary hazelnut allergy when combined with component testing, such as Cor a 1, Cor a 8, Cor a 9, and Cor a 14.
Support clinical or research assessment of hazelnut allergy, while recognizing that a medically supervised oral food challenge may be required for confirmation.
Contribute to evaluation of children with suspected hazelnut allergy, particularly when storage-protein components are measured to improve diagnostic specificity.

Specimen Types

Serum from venous blood.
Plasma may be accepted by some assays, according to the testing laboratory’s validated specimen requirements.
Capillary blood may be used in selected validated testing systems, but it is not universal.

Measurement Methods

Allergen-specific serum IgE immunoassay.
Fluorescence enzyme immunoassay or enzyme-linked immunoassay platforms.
Single-allergen testing using hazelnut extract.
Component-resolved diagnostics measuring IgE to individual hazelnut proteins, including Cor a 1, Cor a 8, Cor a 9, and Cor a 14.
Multiplex allergen microarray testing in selected clinical or research settings.

Test Preparation and Influencing Factors

Fasting is generally not required for an allergy blood test, although specific collection instructions may vary.
Antihistamines usually do not affect serum specific-IgE measurement, but all medications and supplements should be reported to the healthcare professional.
Antihistamines can interfere with skin-prick testing, so medication instructions differ if blood testing and skin testing are performed together.
Recent exposure to hazelnut is not required before blood collection, and hazelnut should not be deliberately consumed to influence the result.
Results should be interpreted with the patient’s reaction history, timing of symptoms, exposure amount, age, geographic pollen exposure, and other allergy findings.
A positive result may represent sensitization without clinical reactivity and may occur because of cross-reactivity, including pollen-associated sensitization.
The concentration of hazelnut-specific IgE does not reliably predict the severity of a future reaction.
Assay cutoffs, reporting units, calibration, and reference categories vary by method; results should be interpreted using the reporting laboratory’s reference information.
A negative result reduces the likelihood of IgE-mediated hazelnut allergy but does not replace clinical assessment when the history is strongly suggestive.
Large, nonselective food-allergen panels can produce misleading positive results and are not recommended without a relevant clinical history.