Biomarker: F023-IgE Crab

Overview

F023-IgE Crab measures serum allergen-specific immunoglobulin E (sIgE) antibodies directed against crab proteins, commonly associated with Callinectes species. IgE is an antibody involved in immediate hypersensitivity reactions, including hives, gastrointestinal symptoms, respiratory symptoms, and anaphylaxis. A detectable or elevated result indicates sensitization to crab but does not by itself confirm clinical allergy or predict reaction severity. The test is clinically useful when interpreted with the patient’s exposure history, symptoms, and, when necessary, skin testing or a supervised oral food challenge.

Clinical Use Cases

Support evaluation of suspected IgE-mediated crab allergy.
Investigate immediate symptoms occurring after crab or shellfish exposure.
Assess patients who cannot undergo skin-prick testing because of skin disease, medication use, or risk of a severe reaction.
Complement the clinical history and skin-prick testing during food-allergy evaluation.
Monitor whether sensitization may have changed over time, when clinically appropriate.
Support research on crab-allergy diagnosis and crab allergen components, including hemocyanin.

Specimen Types

Venous blood, typically processed to obtain serum.
Serum is the usual specimen for quantitative allergen-specific IgE testing.

Measurement Methods

Immunoassay for allergen-specific IgE, reported using the laboratory’s validated quantitative or semiquantitative system.
Solid-phase immunoassays, including fluorescent or enzyme-linked methods.
Multiplex allergen-specific IgE platforms may measure crab together with other food allergens.
Skin-prick testing and supervised oral food challenge may be used as complementary clinical assessments but do not measure F023-IgE directly.
Component-resolved assays for individual crab proteins, such as hemocyanin, may be used in specialized research or clinical settings, although they are distinct from whole-crab F023-IgE testing.

Test Preparation and Influencing Factors

Fasting is generally not required for an allergy blood test.
Tell the healthcare professional about all medications and supplements. Do not stop antihistamines or other medicines unless specifically instructed.
Results should be interpreted with the timing of exposure, symptoms, medical history, and other allergy-test findings.
A positive result indicates sensitization, which may occur without clinical reactivity or symptoms.
Cross-reactivity with related shellfish allergens may contribute to a positive result without proving a reaction to crab specifically.
The measured sIgE concentration does not reliably predict the severity of a future allergic reaction.
Broad testing without a relevant clinical history can increase the likelihood of false-positive results.
Reference ranges, reporting units, and classification categories may vary among assay systems.