Biomarker: F61-IgE Sardine/Pilchard

Overview

F61-IgE Sardine/Pilchard measures immunoglobulin E (IgE) antibodies in blood that specifically recognize sardine or pilchard allergens. IgE is involved in immediate-type allergic reactions, and fish allergens commonly include muscle proteins such as parvalbumin. A detectable or elevated result indicates sensitization, but it does not by itself confirm a clinical sardine allergy or predict reaction severity. The test is clinically useful when interpreted with the patient’s reaction history and, when necessary, skin testing or a medically supervised oral food challenge.

Clinical Use Cases

Supports evaluation of suspected IgE-mediated allergy to sardine or pilchard.
Helps identify sensitization when a patient has experienced symptoms after eating fish.
Assists evaluation when skin-prick testing is unsuitable because of extensive skin disease, medication use, or concern about an immediate reaction.
Supports assessment of possible reactions to individual fish species, recognizing that sensitization to one fish may not reliably predict allergy or tolerance to another species.
May be used with clinical history, skin-prick testing, and oral food challenge when determining whether sardine or pilchard should be avoided.

Specimen Types

Venous blood, typically submitted as serum.
Plasma may be accepted by some assay systems, subject to the laboratory’s requirements.

Measurement Methods

Quantitative serum allergen-specific IgE immunoassay.
Fluorescence enzyme immunoassay or other automated solid-phase immunoassay.
Enzyme-linked immunosorbent assay and chemiluminescent immunoassay may also be used for specific IgE measurement.
Results are commonly reported in allergen-specific IgE units such as ( \text{kUA/L} ), with assay-specific reference categories.

Test Preparation and Influencing Factors

Fasting is generally not required for an allergy blood test.
Antihistamines usually do not affect serum specific-IgE measurement, although they can affect skin-prick testing. Medication instructions should be confirmed with the ordering clinician.
Do not stop prescription or over-the-counter medicines unless instructed by a healthcare professional.
Recent exposure to sardine or pilchard is not generally required before specimen collection.
Total or allergen-specific IgE levels may vary with age, atopic disease, smoking, parasitic infection, and other clinical factors.
A positive result indicates sensitization and may reflect cross-reactivity with allergens from other bony fish; it does not establish that ingestion will cause symptoms.
The concentration of specific IgE does not reliably predict the severity of a future allergic reaction.
Broad food-allergen testing without a compatible clinical history can increase the likelihood of clinically irrelevant positive results.