Proceeds from website advertising help sustain Lab Tests Online. AACC is a not-for-profit organization and does not endorse non-AACC products and services.

Allergy Blood Testing

Print this article
Share this page:
Also known as: Allergy Screen
Formal name: Allergen-specific IgE Antibody Test

At a Glance

Why Get Tested?

To help diagnose allergies; sometimes to monitor the effectiveness of immunotherapy (desensitization) treatment

When to Get Tested?

When you have symptoms such as hives, dermatitis, nasal congestion, red itchy eyes, asthma, or abdominal pain that your health care provider suspects may be caused by an allergy

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

None

The Test Sample

What is being tested?

Immunoglobulin E (IgE) is a class of antibody (immune protein) associated with allergic reactions. It is normally found in very small amounts in the blood. This test measures the amount of allergen-specific IgE in the blood in order to detect an allergy to a particular substance.

IgE is an antibody that functions as part of the body's immune system, its defense against "intruders." When someone with a predisposition to allergies is exposed to a potential allergen such as food, grass, or animal dander for the first time, that person becomes sensitized. The person's body perceives the potential allergen as a foreign substance and produces a specific IgE antibody that binds to specialized mast cells in the skin, respiratory system, and gastrointestinal tract, and to basophils (a type of white blood cell) in the bloodstream. With the next exposure, these attached IgE antibodies recognize the allergen and cause the mast and basophil cells to release histamine and other chemicals, resulting in an allergic reaction that begins at the exposure site.

Each allergen-specific IgE antibody test performed is separate and very specific: honeybee versus bumblebee, egg white versus egg yolk, giant ragweed versus western ragweed. Groupings of these tests, such as food panels or regional weed, grass, and mold panels, can be done. Alternatively, the health practitioner may pick and choose selectively from a long list of individual allergens suspected of causing a person's allergies.

While the traditional method for blood testing was the RAST (radioallergosorbent test), it has been largely replaced with newer IgE-specific immunoassay methods. Some health practitioners continue to refer to all IgE allergy blood tests as RAST even though it is not the exact assay that the testing laboratory uses.

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.

The Test

Common Questions

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



Please indicate whether you are a   
  
  



You must provide a valid email address in order to receive a response.



| Read The Disclaimer


Spam Prevention Equation

| |

Article Sources

« Return to Related Pages

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.

Sources Used in Current Review

Zieve, David. (Updated 2012). Allergy testing – skin. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003519.htm through http://www.nlm.nih.gov. Accessed October 2013.

American Academy of Allergy Asthma & Immunology. (Updated 2013). Allergic Reactions: Tips to Remember. Available online at http://www.aaaai.org/conditions-and-treatments/library/at-a-glance/allergic-reactions.aspx through http://www.aaaai.org. Accessed October 2013.

American Academy of Allergy Asthma & Immunology (@2010). Allergy Testing. Available online at http://www.acaai.org/allergist/allergies/treatment/diagnosing-allergies/pages/allergy-testing.aspx through http://www.aaaai.org. Accessed October 2013.

Fischbach, F.T. (2004). A Manual of Laboratory & Diagnostic Tests. 7th Edition., Lippincott Williams & Wilkins, Philadelphia.

(Updated Jan 17, 2014) Diaz R. Diagnostic Allergy Testing. Medscape Reference. Availalble online at http://emedicine.medscape.com/article/2068676-overview#a1 through http://emedicine.medscape.com. Accessed January 2014.

(March 2008) Bernstein L, et al. Allergy Diagnostic Testing: An Updated Practice Parameter. Annals of Allergy, Asthma and Immunology. March 2008; Volume 100, Number 3, Supplement 3. Available online through http://www.aaaai.org. Accessed January 2014.

(July 18, 2012) National Institute of Allergy and Infectious Diseases. What Makes and Allergen an Allergen. Available online at http://www.niaid.nih.gov/topics/allergicDiseases/research/Pages/whatMakesAllergens.aspx through http://www.niaid.nih.gov. Accessed January 2014.

Sources Used in Previous Reviews

Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.

Sicherer, S. (1999, January 15). Manifestations of Food Allergy: Evaluation and Management. American Family Physician [On-line serial]. Available online at http://www.aafp.org/afp/990115ap/415.html through http://www.aafp.org.

American Academy of Family Physicians (1999, January 15). Food Allergies: Just the Facts. American Family Physician [On-line serial]. Available online at http://www.aafp.org/afp/990115ap/990115f.html through http://www.aafp.org.

ARUP. Immunoglobulin E. Guide to Clinical Laboratory Testing [On-line information]. Available online at http://www.aruplab.com/guides/clt/tests/clt_ijk4.htm through http://www.aruplab.com.

Sicherer, S. (2001, April 5th last update). Food Allergy Testing: Questions and Answers. Food Allergy News Reprint [On-line information]. Available online at http://www.foodallergy.org/topics_archive/testing.html through http://www.foodallergy.org.

Formanek, R. (2001, July-August). Food Allergies: When Food Becomes the Enemy. U.S. Food and Drug Administration, FDA Consumer magazine [On-line serial]. Available online at http://www.fda.gov/fdac/features/2001/401_food.html through http://www.fda.gov.

MEDLINEplus (2002, January 2, Updated). Allergies. MEDLINEplus Health Information [On-line Information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000812.htm.

MEDLINEplus (2002, January 2, Updated). Allergy testing. MEDLINEplus Health Information [On-line Information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003519.htm.

WAO [2000-2002]. Overview of Allergy, Its Diagnosis and Treatment. World Allergy Organization [On-line information]. Available online at http://www.worldallergy.org/public/descriptions_of_allergies/overview.shtml through http://www.worldallergy.org.

National Institute of Allergy and Infectious Disease (1998 February). Something in the Air: Airborne Allergens. WebMD [On-line serial]. Available online at http://my.webmd.com/content/article/1680.50308 through http://my.webmd.com.

National Institute of Allergy and Infectious Diseases (1999 January, last revision). Food Allergy and Intolerances. WebMD [On-line serial]. Available online at http://my.webmd.com/content/article/1680.50303 through http://my.webmd.com.

Pagana, K. D. & Pagana, T. J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 38-44.

(© 2010). Tips to Remember: Allergic Reactions. American Academy of Allergy Asthma and Immunology, [On-line information]. Available online at http://www.aaaai.org/patients/publicedmat/tips/whatisallergicreaction.stm through http://www.aaaai.org. Accessed February 2010.

(© 2010). Tips to Remember: Asthma & Allergy Medications. American Academy of Allergy Asthma and Immunology [On-line information]. Available online at http://www.aaaai.org/patients/publicedmat/tips/asthmaallergymedications.stm through http://www.aaaai.org. Accessed February 2010.

Mayo Clinic Staff (2009 June 24). Allergy medications: Know your options. MayoClinic.com [On-line information]. Available online at http://www.mayoclinic.com/health/allergy-medications/AA00037/METHOD=print through http://www.mayoclinic.com. Accessed February 2010.

Hinshaw, W. D. et. al. (Updated 2009 June 02). Hypersensitivity Reactions, Delayed. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/136118-overview through http://emedicine.medscape.com. Accessed February 2010.

Anand, M. and Routes, J. (Updated 2009 June 16).Hypersensitivity Reactions, Immediate. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/136217-overview through http://emedicine.medscape.com. Accessed February 2010.

Mayo Clinic Staff (2009 April 03). Allergy Skin Tests. MayoClinic.com [On-line information]. Available online at http://www.mayoclinic.com/health/allergy-tests/MY00131/METHOD=print through http://www.mayoclinic.com. Accessed February 2010.

(© 2009). Tips to Remember: What is Allergy Testing? American Academy of Allergy Asthma and Immunology, [On-line information]. Available online at http://www.aaaai.org/patients/publicedmat/tips/whatisallergytesting.stm through http://www.aaaai.org. Accessed February 2010.

LTO logo

Get the Mobile App

Follow Us