Biomarker: F202-IgE Cashew Nut
Overview
F202-IgE Cashew Nut measures serum immunoglobulin E (IgE) antibodies specific to cashew nut proteins. Cashew allergens include Ana o 1, Ana o 2, and Ana o 3, with Ana o 3 being particularly associated with clinically relevant cashew allergy. A detectable or elevated result indicates sensitization to cashew, but it does not by itself confirm a food allergy or predict reaction severity. The test is clinically useful when interpreted with the patient’s exposure history and symptoms, and may help determine whether additional evaluation, including component testing or a medically supervised oral food challenge, is appropriate.
Clinical Use Cases
- Evaluation of suspected immediate hypersensitivity reactions after cashew exposure.
- Identification of cashew sensitization in patients with suspected tree-nut allergy.
- Support for the differential diagnosis of food allergy when skin testing is unsuitable or cannot be performed.
- Assessment of cashew-specific sensitization alongside clinical history and, when indicated, skin-prick testing.
- Use in component-resolved diagnostics, particularly when Ana o 3 testing is available, to improve assessment of clinically relevant cashew allergy.
- Research assessment of cashew-specific IgE responses and their relationship to outcomes of oral food challenges.
Specimen Types
- Serum obtained from venous blood.
- Plasma may be accepted by some assay systems, depending on the laboratory method and validation.
Measurement Methods
- Automated in-vitro allergen-specific IgE immunoassays.
- Fluorescence enzyme immunoassay, including ImmunoCAP-type methods.
- Chemiluminescent or other solid-phase immunoassays.
- Immunoassays using cashew-nut extract as the allergen source.
- Component-resolved immunoassays for cashew proteins such as Ana o 1, Ana o 2, and Ana o 3, when available.
Test Preparation and Influencing Factors
- Fasting is generally not required for an allergy blood test.
- Antihistamines usually do not interfere with blood-based specific-IgE testing, unlike some skin tests, but medications should still be reported to the ordering clinician.
- Do not stop prescription or over-the-counter medicines unless instructed by a healthcare professional.
- Results should be interpreted with the timing, amount, and form of cashew exposure and the associated symptoms.
- A positive result indicates sensitization and may occur without clinical allergy.
- A negative result does not completely exclude clinically relevant allergy.
- Total IgE concentration, age, assay platform, cutoff values, and population studied can influence interpretation.
- Cashew-specific IgE concentration does not reliably predict the severity of a future reaction.
- Oral food challenges should only be performed under appropriate medical supervision because they can cause allergic reactions.
Synonyms
- Cashew nut-specific IgE
- Cashew-specific IgE
- Cashew allergen-specific immunoglobulin E
- Cashew nut IgE antibody
- Cashew nut (f202) IgE
- F202 IgE
- Anacardium occidentale-specific IgE
- Serum IgE to cashew nut
- Cashew RAST
- Cashew component-resolved IgE, when referring to component testing such as Ana o 3
This information is provided for general educational purposes and is not medical advice. Biomarker information may describe testing methods, measurements, or interpretations that vary by laboratory or specific test. For details about a particular lab test, including biomarkers measured, specimen type, collection requirements, preparation, and turnaround time, please refer to the individual test description. Talk with a licensed health care provider about your results.
