Biomarker: F203-IgE Pistachio Nut

Overview

F203-IgE Pistachio Nut measures pistachio-specific immunoglobulin E (IgE) antibodies in blood. IgE is an antibody involved in immediate allergic reactions, including reactions to food proteins. A detectable or elevated result indicates sensitization to pistachio but does not by itself confirm a clinical allergy, predict reaction severity, or establish that pistachio causes symptoms. The test is clinically useful when interpreted with the patient’s history, symptoms, and, when necessary, a supervised oral food challenge.

Clinical Use Cases

Support evaluation of suspected IgE-mediated pistachio allergy.
Identify sensitization to pistachio in patients with a compatible history of symptoms after ingestion.
Complement skin-prick testing when skin testing is unsuitable, inconclusive, or affected by medications or skin disease.
Help evaluate possible cross-sensitization among tree nuts, particularly pistachio and cashew.
Support assessment of whether a previously suspected food allergy may have resolved over time.
Contribute to research involving food-allergen sensitization and diagnostic test performance.

Specimen Types

Venous blood, typically analyzed as serum.
Plasma may be accepted by some laboratory platforms, depending on the assay.

Measurement Methods

In-vitro serum allergen-specific IgE immunoassay.
Fluorescence-based enzyme immunoassays, including ImmunoCAP-type methods.
Other validated automated or enzyme-linked specific-IgE platforms.
Results are commonly reported in kUA/L or kU/L, with assay-specific decision categories.

Test Preparation and Influencing Factors

Fasting is generally not required for a blood-specific IgE test.
Patients should report all medications and supplements. Antihistamines commonly affect skin-prick testing but generally do not prevent blood-specific IgE measurement.
Medication changes should only be made under instructions from a healthcare professional.
Testing should be guided by a compatible clinical history rather than used as unrestricted screening, because false-positive sensitization results can occur.
Cross-reactivity with related tree-nut allergens may produce a positive pistachio-specific IgE result without clinically relevant pistachio allergy.
Total IgE elevation, smoking, parasitic infection, and nonspecific assay binding may affect interpretation.
A positive result indicates sensitization and must be interpreted with symptoms and exposure history.
The concentration of pistachio-specific IgE does not reliably predict reaction severity.
A supervised oral food challenge remains the reference method for confirming or excluding food allergy when the diagnosis is uncertain.