About the Test
Purpose of the test
The purpose of a total IgE test is to measure the sum of all kinds of IgE antibodies that are in the blood. The test is mainly used for diagnosis and treatment planning.
Diagnosis is the process of determining the cause of symptoms. Total IgE levels can be affected by many conditions, so total IgE testing by itself does not establish a diagnosis. However, a total IgE test may be helpful in the diagnostic process for specific health conditions that can cause abnormal total IgE levels including:
- Infections with parasites
- Allergic bronchopulmonary aspergillosis, which is an allergic reaction to a type of fungal infection in the lungs
- Certain kinds of immune disorders or cancers of the immune system
Infrequently, total IgE testing may be performed as part of allergy testing because many allergic reactions involve the production of IgE antibodies to normally harmless substances. However, total IgE testing cannot identify specific allergies or conclusively determine if a person has allergies at all. For this reason, it is not commonly used in allergy testing.
Treatment planning involves deciding what treatment may be appropriate for a patient. For people with asthma tied to allergies, a total IgE test may be used to determine whether certain types of treatment are likely to be beneficial.
What does the test measure?
The total IgE test measures the quantity of immunoglobulin E (IgE) in the blood. IgE is a type of antibody. Antibodies are proteins that the immune system produces to help defend against potential threats.
The immune system produces IgE antibodies for many specific substances. A total IgE test measures the sum of all these different IgE antibodies in the blood.
When should I get a total IgE test?
A total IgE test is usually only used in specific circumstances.
Your doctor may suggest a total IgE test if you have symptoms of an immune disorder, parasitic infection, or an allergic reaction from a fungal infection in your lungs. A total IgE test may be prescribed if you have asthma or if you have allergy symptoms like itchy or watery eyes, congestion, or sneezing.
Your doctor may also recommend total IgE testing if you have previously been diagnosed with asthma caused by allergies. In this situation, testing may help determine the right treatment for you and identify the right dosage of certain asthma medications.
Finding a Total IgE Test
How to get tested
Total IgE testing can be ordered by your primary care provider or a medical specialist. The test requires a blood sample that is usually drawn from a vein in your arm in a doctor’s office, health clinic, or hospital.
Can I take the test at home?
Some at-home tests are available that include a measurement of total IgE. In these tests, total IgE is usually measured along with many specific forms of IgE associated with certain allergens.
For these at-home tests, a blood sample is taken by pricking your fingertip and applying a drop of blood to a special test paper. That test paper is then sent to a lab, and results are made available electronically.
Because many conditions can affect IgE levels, it is important to talk with a doctor about total IgE testing. At-home tests should not be used in lieu of seeing a health care provider.
How much does the test cost?
The cost of total IgE testing will depend on whether you have medical insurance that covers this test. Many insurance plans cover this testing if it is prescribed by a licensed health care professional. Check with your doctor and insurance provider about the costs of testing and whether you will be required to cover any copays or deductibles.
Taking a Total IgE Test
Your doctor or another health professional will take a sample of blood from a vein in your arm. This procedure is usually done in a medical office or hospital.
Before the test
There are no special preparations or precautions to take prior to a total IgE blood test.
During the test
During a total IgE test, a small needle is placed into your vein. Beforehand, a health professional may tie an elastic band around your upper arm. They will also clean part of your skin with an antiseptic.
After the needle is inserted into your vein, blood is withdrawn into a vial or test tube. You may feel a slight sting when the needle is inserted. The test itself usually takes less than five minutes to complete.
After the test
Once the test is over, you can resume all normal activities. There are very few risks associated with a total IgE blood test. You may have some slight discomfort or bruising in your arm, but this typically resolves quickly.
Total IgE Test Results
Receiving test results
Results from your total IgE test are usually available within a few business days after the laboratory receives your blood sample. Results may be provided directly by your doctor, and you may also get a test report by mail or electronically.
Interpreting test results
Your total IgE test results show the amount of immunoglobulin E in your blood. Test results are displayed as international units per milliliter of blood (IU/mL) or nanograms per milliliter of blood (ng/mL).
Laboratory results usually display your test result along with a reference range. Reference ranges are based on test results from large groups of people. These ranges help outline the expected total IgE levels in healthy people.
Your test results are interpreted in the context of your overall health, including any symptoms that you may have. Total IgE levels may help identify certain conditions, but this test alone is rarely able to make a diagnosis. For this reason, the meaning of your test results should always be explained by your doctor.
Elevated levels of total IgE can be caused by a number of medical conditions including parasitic infections, some allergies and asthma, certain immune disorders, and some types of cancer. Additional tests are typically necessary to determine the underlying cause.
It is also possible to have very low levels of total IgE as a result of some types of diseases that cause abnormal immune function.
Are test results accurate?
Laboratory methods can typically measure total IgE levels accurately. However, no test is perfectly accurate. In addition, because multiple factors can affect IgE levels, the test alone may not clearly identify any specific medical condition.
Do I need follow-up tests?
Total IgE testing alone is rarely adequate to diagnose a medical condition. As a result, if you have abnormal total IgE test results, your doctor may recommend additional testing. The most appropriate follow-up tests depend on your symptoms, overall health, and total IgE levels.
Questions for your doctor about test results
It may be helpful to make a list of questions for your doctor about your total IgE test results, including:
- What are my total IgE levels?
- Were my total IgE levels within the normal range?
- Do I need follow-up testing?
Total IgE test vs. specific IgE test
While the total IgE test measures the sum of all kinds of IgE in the blood, a specific IgE test looks for particular IgE antibodies that are linked to certain substances or allergens.
Because they measure different things, these two tests have different purposes. A specific IgE test can offer more detailed information about particular immune responses. A total IgE test may provide more information when diagnosing certain conditions and planning treatment for allergic asthma.