At a Glance
Why Get Tested?
To screen for an allergic disease; sometimes to screen for a parasitic infection
When to Get Tested?
When you have periodic or persistent skin, lung, or digestive symptoms that suggest allergies; when a doctor suspects a parasitic infection
A blood sample drawn from a vein in your arm
Test Preparation Needed?
The Test Sample
What is being tested?
Immunoglobulin E (IgE) is an antibody that is produced by the body’s immune system in response to a perceived threat. It is one of five classes of immunoglobulins (A, G, M, D, and E) and is normally present in the blood in very small amounts. This test measures the amount of IgE in the blood.
Immunoglobulins are proteins that play a key role in the body's immune system. They are produced by specific immune cells called plasma cells and respond to bacteria, viruses, and other microorganisms as well as substances that are recognized as "non-self" and harmful antigens.
Immunoglobulin E is associated with allergic responses including asthma and to a lesser degree with immunity to parasites. With allergies, the body overreacts to one or more substances in the environment called allergens that do not typically cause a response in other people. A person may develop an allergy when they are exposed to an allergen, which is then perceived as a threat. Allergens may include plant pollen, peanuts, eggs, strawberries, bee venom, and hundreds of other potential substances. During an initial exposure, also called sensitization, an allergic person produces an IgE specifically directed against that allergen. IgE binds to specialized white blood cells, resulting in the release of a number of substances, including histamine. In allergic/asthmatic people, this can cause constriction of the bronchi in the lungs. These substances are also responsible for the running nose, itchy eyes, and skin itching that occur in people with allergies.
Each time an allergic person is exposed to a specific allergen(s) after the initial exposure, IgE is rapidly produced, increasing to levels that trigger an allergic reaction. The severity of the reaction and symptoms associated with each episode can range from a localized reddening and itching of the skin, to respiratory distress, to vomiting and diarrhea, and in some cases to life-threatening anaphylaxis. Severity will vary from person to person, can vary from episode to episode, and may worsen over time.
The total IgE test measures the overall quantity of immunoglobulin E in the blood, not the amount of a specific type. It can be used to detect an allergic response in the body – rather than a specific allergy. This test may compliment the information provided by allergy tests that detect allergen-specific IgE.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
Ask a Laboratory Scientist
This form enables you to ask specific questions about your tests. Your questions will be answered by a laboratory scientist as part of a voluntary service provided by one of our partners, American Society for Clinical Laboratory Science. If your questions are not related to your lab tests, please submit them via our Contact Us form. Thank you.
* indicates a required field
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Pagana, K. D. & Pagana, T. J. (© 2011). Mosby’s Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 581-584.
Daller, J. (Updated 2011 August 1). Hyperimmunoglobulin E syndrome. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/001311.htm. Accessed January 2012.
Mayo Clinic Staff (2011 July 28). Primary Immunodeficiency. Mayo Clinic [On-line information]. Available online at http://www.mayoclinic.com/health/primary-immunodeficiency/DS01006 through http://www.mayoclinic.com. Accessed January 2012.
Jyonouchi, H. (Updated 2011 August 2). Hyperimmunoglobulinemia E (Job) Syndrome. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/886988-overview#showall through http://emedicine.medscape.com. Accessed January 2012.
(© 1995-2012). Test ID: IGE Immunoglobulin E (IgE), Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/8159 through http://www.mayomedicallaboratories.com. Accessed January 2012.
Hill, H. and Wittwer, C. (Updated 2011 April). Neutrophil Disorders. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/NeutrophilDisorders.html?client_ID=LTD through http://www.arupconsult.com. Accessed January 2012.
Delgado, J. et. al. (Updated 2011 January). Immunoglobulin Disorders. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/ImmunoglobulinDisorders.html?client_ID=LTD#tabs=0 through http://www.arupconsult.com. Accessed January 2012.
Dowshen, S. (Reviewed 2011 February). Blood Test: Immunoglobulin E (IgE). KidsHealth from Nemours [On-line information]. Available online at http://kidshealth.org/parent/system/medical/test_immunoglobulin_e.html through http://kidshealth.org. Accessed January 2012.
Lowry, F. (2010 November 18). Age-Related IgE Levels on the Rise in the United States. Medscape Medical News from the: American College of Allergy, Asthma & Immunology (ACAAI) 2010 Annual Scientific Meeting [On-line information]. Available online at http://www.medscape.com/viewarticle/732797 through http://www.medscape.com. Accessed January 2012.
(Updated 2011 August). Handout on Health: Atopic Dermatitis. National Institute of Arthritis and Musculoskeletal and Skin Diseases [On-line information]. Available online at http://www.niams.nih.gov/Health_Info/Atopic_Dermatitis/default.asp through http://www.niams.nih.gov. Accessed January 2012.
Heimall, J. et. al. (Updated 2010 August 4). Job Syndrome. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/1547969-overview through http://emedicine.medscape.com. Accessed January 2012.