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Blood Testing for Allergies
Blood tests can tell if someone has allergies by finding antibodies in the blood that react to allergens. When an allergic reaction is caused by the immune system, it sends out more Immunoglobulin E (IgE) into the bloodstream. You and your allergist should work together to figure out which test is best for you.
Make An AppointmentTypes 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.
RAST Test
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.
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.
*Note: Determining which test is the best option should be done in consultation with your allergist and involves several different factors, including age, suspected allergy, and the severity of a patient’s reaction to an allergen.
Are Skin Or Blood Tests Better?
You should work in consultation with your allergist to determine which test is the best option for you. In general, allergists prefer to avoid skin tests in younger patients. Skin tests are also riskier for those with eczema or other skin conditions.
Blood tests such as the ELISA test can also provide the detail needed to develop a customized treatment plan. One advantage of skin tests, however, is that they produce fast results, while blood tests can take a few days to process. If you are interested in allergy testing, discuss all your options with your allergist.