Biomarker: F245-IgE Egg, Whole

Overview

F245-IgE Egg, Whole measures immunoglobulin E (IgE) antibodies in blood that specifically recognize proteins in whole hen’s egg. IgE is an immune antibody involved in immediate-type allergic reactions. A detectable or elevated result indicates sensitization to egg proteins, but it does not by itself confirm clinical egg allergy or predict reaction severity. The test is clinically useful when interpreted with the patient’s history, physical examination, and, when necessary, skin testing or a medically supervised oral food challenge.

Clinical Use Cases

Supports evaluation of suspected IgE-mediated egg allergy.
Helps assess sensitization in patients with a history of immediate symptoms after eating egg-containing foods.
Contributes to evaluation when the clinical history and skin-prick testing are inconclusive or skin testing is not available.
May help guide selection of patients for further assessment with egg-white, egg-yolk, or molecular component-specific IgE testing.
May be used to monitor changes in sensitization over time in patients being evaluated for possible resolution of egg allergy, although results must be interpreted clinically.
Supports, but does not replace, a medically supervised oral food challenge, which is the diagnostic reference standard.

Specimen Types

Serum obtained from venous blood.
Plasma may be accepted by some assay systems, depending on the laboratory method and validation requirements.

Measurement Methods

Quantitative in-vitro allergen-specific IgE immunoassay.
Fluorescence-based immunoassay, including solid-phase assays in which egg allergen is coupled to a solid carrier.
Chemiluminescent enzyme immunoassay.
Enzyme-linked immunosorbent assay, primarily in research settings.

Test Preparation and Influencing Factors

Fasting is generally not required for an allergy blood test.
Patients should report all prescription medicines, over-the-counter medicines, vitamins, and supplements. Medicines should not be stopped unless instructed by a health care professional.
Unlike skin-prick testing, antihistamines generally do not prevent collection of a valid blood sample, although the ordering clinician or laboratory should provide test-specific instructions.
Results should be interpreted with the timing, amount, and form of egg exposure, including raw, lightly cooked, or extensively heated egg.
Total IgE, age, atopic dermatitis, other allergic diseases, and cross-reactive sensitization may influence interpretation.
A positive result indicates sensitization and may occur without symptoms after egg ingestion.
The concentration of egg-specific IgE does not reliably predict the severity of a future reaction.
No single egg-specific IgE cutoff is diagnostic for egg allergy across all ages and clinical settings.
Testing should be guided by a compatible clinical history because indiscriminate food allergy testing can produce clinically irrelevant positive results.
A medically supervised oral food challenge may be required when the history and test results do not agree.