For adults, elevated levels of immunoglobulin E or IgE are above 423 international units per milliliter of blood, according to WebMD. Normal values of IgE rest between 3 and 423 international units per milliliter of blood.
IgE antibodies attack foreign substances, explains WebMD. These antibodies are found in the lungs, skin and mucous membranes, such as the lining the nose and mouth.
IgE blood levels increase in response to allergens, such as mold, pollen, pet dander and certain foods, notes the American Association for Clinical Chemistry. IgE levels also rise when an individual has a parasitic infection. To pinpoint the cause of high IgE levels, a physician may test for allergen-specific IgE antibodies.