RAST (Radio Allergo Sorbent Test) is a test that checks the existence of specific antibodies against various elements suspected of being the cause of allergy (inhaled or food). Today the test is usually performed using another technology: ELISA (Enzyme-Linked Immuno Sorbent Assay).However, it continues to be called RAST by some persons.
For this test, a blood sample is taken. A few days later the results reflect the existence or not of antibodies against the inhaled particles or foods tested. This test is less useful than the prick test but there are times that due to a skin disease, inability to stop anti-histamine drugs, the physician is forced to order this test instead of performing a prick test.