The total IgE test may be used to screen for and detect allergic diseases. It may be ordered by itself, before, or along with allergen-specific IgE tests – depending upon whether or not a person or doctor has identified potential substances to which the person may be allergic.
IgE can be increased with parasitic infections, so a total IgE test is sometimes used as a screening test if a parasitic infection is suspected.
A total IgE test may be ordered when a person has periodic or persistent symptoms that may be due to an allergic reaction, especially when the potential allergen is unknown. Symptoms may include those that suggest skin, respiratory, and/or digestive involvement, such as:
An increased total IgE level indicates that it is likely that a person has one or more allergies. Allergen-specific IgE levels will increase after an exposure and then decline over time, thus affecting the total IgE level. If a person is allergic to a seasonal substance, such as pollen, then both the specific IgE and total IgE would be expected to increase during the time of year when the allergen is present. If someone has one or more food allergies, then the total IgE level would mirror exposures to these foods. If someone is allergic to something that they are constantly around, such as mold in a house or cat dander, then the total IgE level may be persistently increased.
An elevated level of total IgE indicates an allergic process is likely present, but it will not indicate what a person is allergic to. In general, the greater the number of things a person is allergic to, the higher the total IgE level may be. An IgE elevation can also indicate the presence of a parasitic infection but cannot be used to determine the type of infection.
A normal IgE level makes it less likely that a person has allergies but does not rule them out due to the length of time between exposures. In between exposures, a person's IgE level may drop.
Sometimes an individual has a condition that affects their immune system and will not produce normal amounts of immunoglobulins. In this case, a person could have an allergy that is not reflected by the total IgE test result.
In order to identify specific allergies, a doctor must order tests that detect allergen-specific IgE. If a person is suspected of having an allergy to cats, then a cat dander IgE test must be ordered. If the person actually has an allergy to dogs, it will not be detected with this test. For this reason, doctors may screen with a total IgE test, then run panels of substance-specific IgE tests. These panels may include a range of common allergens or similar types of allergens, such as various grasses, pollen, molds, pet dander, and/or foods.
A person's symptoms during an allergic episode do not necessarily correlate with their total IgE level.
Infrequently, an IgE test may be ordered to help diagnose a very rare inherited disease called hyperimmunoglobulin E syndrome (Job syndrome). People with this disease often have significantly higher than normal IgE levels and may have eczema, recurrent sinus and lung infections, bone defects, and severe skin infections. A greatly increased IgE concentration may indicate that an individual has inherited this condition. Additional testing can be performed to detect a mutation in the STAT3 gene that has been associated with this disorder.
Rarely, the IgE test is used to help diagnose and monitor multiple myeloma that produces monoclonal IgE.
This article was last reviewed on April 19, 2012. | This article was last modified on February 24, 2015.
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