The CBC (complete blood count) is a routine blood test that measures the composition of blood cells within the blood. The test provides a count of the type and numbers of specific blood cells, including white blood cells, red blood cells and blood platelets. While used to screen for a variety of conditions, the test can provide specific data regarding the presence of allergies in an individual.

The CBC test takes only a few minutes, and is performed by taking a blood sample from a patient. During this simple procedure, blood is withdrawn from the patient’s arm through a needle inserted into the vein. The blood sample is sent to a laboratory and analyzed.

A CBC test will not conclusively demonstrate the presence of allergies in an individual. However, test results that show increased levels of eosinophils and basophils (types of white blood cells) can suggest an allergic reaction has recently taken place in a patient. The test is often used along with other types of allergy tests (e.g., ELISA, RAST) to more accurately determine the presence of an allergy.

There is generally no special preparation necessary for the CBC test. However, some medications may interfere with a CBC. Patients are urged to follow their physician’s orders carefully about how to take their medications before the test in order to ensure its accuracy.