RAST (Radioallergosorbent test)

The Radioallergosorbent Test (RAST) is a blood test used to identify specific allergies. It measures the amount of allergy-causing antibodies called IgE in your blood that react to certain allergens like pollen, dust, or pet dander. During the test, small amounts of allergens are attached to a solid surface, then mixed with your blood. If you have IgE antibodies to those allergens, they will bind to them. The test uses a radioactive marker to detect this binding, helping doctors determine what substances may trigger allergic reactions and guide appropriate treatment.