IgE Biomarker | Walk-In Lab

Overview

Immunoglobulin E (IgE) is an antibody produced by your immune system that helps fight parasitic infections and mediates allergic responses. IgE antibodies sit on the surface of immune cells like mast cells and basophils, where they recognize and bind to specific antigens. When exposed to an allergen, IgE triggers the release of histamines and other chemical mediators that cause allergic symptoms. While IgE's primary role is to protect against parasitic infections, elevated levels typically indicate allergic disease or certain immune conditions, though normal IgE levels do not exclude the presence of allergies. The biomarker is clinically useful for diagnosing specific allergies and determining candidacy for anti-IgE therapies.

Clinical Use Cases

Diagnosis of allergic rhinitis (hay fever) and allergic conjunctivitis
Evaluation and monitoring of asthma, particularly allergic asthma
Diagnosis of food allergies and identification of specific food allergens
Assessment of atopic dermatitis and chronic urticaria
Detection of parasitic infections
Diagnosis of allergic bronchopulmonary aspergillosis (ABPA)
Identification of candidates for omalizumab (anti-IgE monoclonal antibody) therapy and dosing determination
Evaluation of primary immunodeficiencies and immunodeficiency syndromes
Detection of anaphylaxis risk and monitoring of patients with known allergic conditions

Specimen Types

Serum (preferred: serum gel separator tube)
Red top tube (acceptable alternative)

Measurement Methods

Fluorescence enzyme immunoassay (FEIA)
Electrochemiluminescence immunoassay (ECLIA)
Enzyme-linked immunosorbent assay (ELISA)
Radioallergosorbent test (RAST), now largely replaced by newer methods
ImmunoCAP system (automated analyzer using FEIA technology)

Test Preparation and Influencing Factors

No fasting required for IgE testing
Antihistamine medications can reduce IgE levels and should typically be discontinued before testing; specific timing should be confirmed with the healthcare provider
Asthma inhalers, montelukast, and nasal steroids do not require discontinuation
Specimen should be centrifuged within 2 hours of collection
Samples must be frozen at -20°C for transport and storage
Time of collection does not significantly affect results, though consistent timing may improve comparison of serial measurements
Stress, acute infections, and parasitic infections may transiently elevate IgE levels