Types of blood testing

You may hear several different terms used to reference blood testing for allergies, including RAST, ELISA, and immunoassay testing. Generally speaking, these tests all achieve the same goal: identifying the presence of allergen-related antibodies in the blood.

Formerly called RAST testing, ELISA testing is now the gold standard for allergy blood testing. AllerVie Health performs allergen-specific IgE (Immunoglobulin E) testing, commonly known as ELISA/EIA testing, utilizing ImmunoCAP by ThermoFisher, when conducting allergy diagnostics.


The RAST test was the most common blood test until recently for diagnosing allergies. This test uses radioimmunoassay testing to identify specific antibodies in the blood. As a result, the diagnostician can then confirm specific substances to which the patient is allergic. RAST testing has been replaced in recent years by the ELISA test.

Elisa Test

The enzyme-linked immunosorbent assay test, known as the ELISA for short, identifies the exact amount of specific antibodies in the blood. This provides the detail needed to develop specific and customized plans in the treatment of allergies.

ImmunoCAP™ Tests

ImmunoCAP tests are a form of ELISA test. Since it can be difficult to differentiate between allergies and other respiratory ailments, ImmunoCAP testing gives diagnosticians a way to confirm or rule out the presence of allergies. ImmunoCAP tests can be used in the diagnosis of hundreds of allergens including weeds, mold, pollens, food, and animal dander.

A row of human blood samples in a medical laboratory ready to be tested

How Can Blood Testing Diagnose Allergies?

Blood testing diagnoses allergies by identifying the presence of allergen-related antibodies in the blood. When the body’s immune system triggers an allergic reaction, it releases more Immunoglobulin E (IgE) into the bloodstream. Typically, the acceptable upper limit of IgE is between 150 and 300 UI/ml. When a blood test identifies IgE levels higher than this range, it can serve as confirmation of an allergic response.