"The quantity of immunoglobulin E (IgE) in the blood is measured by a test called a total IgE test, commonly referred to as a quantitative IgE test. Your immune system perceives a foreign substance, such as dust or pollen, as a threat when you have an allergy. Your immune system produces IgE antibodies to combat this threat. The total IgE test counts all the IgE antibodies in your blood, whereas the specific IgE test examines the amount of IgE antibodies produced in response to a specific allergen."