A blood test in which radioimmunoassay is used to measure the presence of IgE antibodies in the blood to detect allergies to various substances, such as certain cosmetics, animal fur, dust, and grasses.
A blood test for allergy that measures minute quantities of immunoglobulin E in blood. People who have type I hypersensitivity reactions to common allergens (e.g., ragweed, trees, molds, milk, eggs, and animal dander) have elevated levels of IgE. For these individuals and others, RAST is safer than skin testing, because it carries no risk of systemic anaphylaxis. RAST is not as sensitive as skin testing, however.
RAST stands for radioallergosorbent test, a form of radioimmunoassay utilized for identifying antibodies (immune system-generated proteins) against distinct antigens (substances capable of eliciting an immune reaction).