Attention: Must-Know Facts About Allergy Blood Testing

What is an Allergy Blood Test?

An examination for allergies in your bloodstream quantifies the level of immunoglobulin E (IgE) present. IgE is an antibody produced by your body. If you have allergies, your IgE levels might be higher than normal.

Allergies are a prevalent, chronic condition involving your immune system. Normally, your immune system creates antibodies to combat viruses, bacteria, and other harmful substances. However, with allergies, your immune system mistakenly identifies harmless substances like pollen or peanuts as threats. To counter these "threats," your immune system produces IgE antibodies, leading to allergy symptoms.

Substances that cause allergies are known as allergens. Common allergens include:

Pollen
Dust
Mold
Animal dander
Certain foods, such as nuts and shellfish
Certain medications, like penicillin

Allergy symptoms vary depending on the type of allergy and can range from itching and sneezing to asthma or even a life-threatening condition called anaphylactic shock.

Alternative names for allergy blood tests encompass IgE sensitivity assessment, Quantitative IgE measurement, Immunoglobulin E analysis, Overall IgE evaluation, Specific IgE detection, RAST screening, CAP examination, and ELISA assay.

What is it used for?

Allergy blood tests are utilized to determine if you have an allergy. Two primary categories of allergy blood tests exist:

A total IgE test measures the overall amount of IgE antibodies in your blood.
A specific IgE test measures the amount of IgE your body produces in response to a particular allergen, with a separate test for each potential allergen.

Why do I need an Allergy Blood Test?

Your healthcare provider might suggest allergy testing if you exhibit symptoms such as:

Stuffy or runny nose
Sneezing
Itchy, watery eyes
Hives (itchy, raised red patches on the skin)
Diarrhea
Vomiting
Shortness of breath
Coughing
Wheezing

An allergy blood test may be recommended if you cannot undergo allergy skin testing, which involves applying allergens to your skin. You might not be suitable for skin testing if you:

Have specific skin conditions
Take certain medications that could affect test results
Are at high risk for a severe allergic reaction to the allergens used in skin testing

In some instances, allergy blood tests are ordered for young children as skin testing might be too uncomfortable for them.

What happens during an Allergy Blood Test?

A medical practitioner will extract a blood sample from a vein in your arm utilizing a slender needle. After inserting the needle, a small amount of blood is collected in a test tube or vial. You might feel a slight sting when the needle is inserted or removed. The procedure typically takes less than five minutes.

Do I have to undertake any preparations beforehand for the examination?

No special preparations are needed for an allergy blood test.

Are there any risks to the test?

There is minimal risk associated with an allergy blood test. You might experience slight pain or bruising at the needle insertion site, but these symptoms usually resolve quickly.

What do the results mean?

A high total IgE test result indicates a potential allergy but does not specify what you are allergic to or the severity of the allergy. A high specific IgE test result suggests you might be allergic to the tested allergen, but the amount of IgE does not determine the severity of your allergy.

If your test results indicate a possible allergy, your provider may refer you to an allergy specialist or develop a treatment plan based on your specific allergens and symptom severity. If you are at risk for anaphylactic shock, it is crucial to avoid your allergens and carry an emergency epinephrine auto-injector.

Discuss any concerns about your test results or allergy treatment plan with your provider.

Are there any additional details I should be aware of regarding an allergy blood test?

Allergy blood tests are not always accurate. False positives can occur, indicating an allergy when there is none, possibly due to mild reactions to certain foods consumed before the test. False negatives, where the test fails to detect an existing allergy, are less common.

Depending on your medical history and symptoms, your provider might recommend an allergy skin test in addition to or instead of an allergy blood test.