Biomarker: F002-IgE Cow's Milk

Overview

F002-IgE Cow's Milk measures immunoglobulin E (IgE) antibodies in blood that specifically recognize proteins in cow's milk. These antibodies are associated with immediate, IgE-mediated allergic reactions after milk exposure, including hives, vomiting, wheezing, or anaphylaxis. A detectable or elevated result indicates sensitization, but it does not by itself confirm clinical allergy or predict reaction severity. The test is clinically useful when interpreted with the exposure history, symptoms, physical examination, and, when necessary, a medically supervised oral food challenge.

Clinical Use Cases

Evaluation of suspected IgE-mediated cow's milk allergy.
Identification of sensitization to cow's milk in patients with symptoms occurring soon after exposure.
Support for diagnostic assessment when skin-prick testing is unsuitable, unavailable, or affected by skin disease or medications.
Assessment of sensitization to individual milk proteins, such as casein, alpha-lactalbumin, or beta-lactoglobulin, when component testing is clinically indicated.
Follow-up of previously identified cow's milk sensitization as part of an allergist-directed assessment.
Research on the diagnosis, natural history, and clinical characteristics of cow's milk allergy.

Specimen Types

Venous blood, processed as serum.
Serum obtained from whole blood collected in a serum or serum-separator tube.
Capillary blood may be used in some validated collection systems, but serum is the usual specimen for laboratory measurement.

Measurement Methods

Quantitative allergen-specific IgE immunoassays performed on serum.
Fluorescent enzyme immunoassay, including ImmunoCAP-based assays.
Chemiluminescent or other automated immunoassays, depending on the laboratory platform.
Component-resolved testing for individual milk proteins, including casein (Bos d 8), beta-lactoglobulin (Bos d 5), and alpha-lactalbumin (Bos d 4).
Results are commonly reported in kUA/L or an equivalent allergen-specific IgE concentration unit.

Test Preparation and Influencing Factors

Fasting is generally not required for a serum-specific IgE blood test.
Patients should report all medications and supplements to the ordering clinician.
Antihistamines generally do not interfere with serum-specific IgE measurement, although they may affect skin-prick testing. Medication changes should be made only on clinical advice.
Testing should be selected based on a focused history rather than broad screening, because positive results can represent sensitization without clinically relevant allergy.
Recent exposure to milk is not usually required before blood collection.
Age, atopic dermatitis, total IgE concentration, assay platform, and the patient’s clinical history can affect interpretation.
A positive result does not establish that symptoms are caused by milk, and the concentration does not reliably predict reaction severity.
A negative result reduces the likelihood of IgE-mediated allergy but does not exclude non-IgE-mediated cow's milk reactions.
During or soon after anaphylaxis, allergen-specific IgE results may be temporarily lower; unexpected negative results may warrant repeat testing after clinical recovery.
Reference ranges, reporting thresholds, and units vary by assay and laboratory.