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Allergy Blood LabTest

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Allergy Blood LabTest
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Allergy Blood LabTest

Allergies affect millions worldwide, causing symptoms that range from mild discomfort to severe, life-threatening reactions. Diagnosing allergies accurately is crucial for effective treatment and management. Among various diagnostic methods, allergy blood tests are increasingly used for their convenience and safety. This article explores everything you need to know about allergy blood tests — their purpose, how they are conducted, the results interpretation, and how they compare with other allergy tests.

What is an Allergy Blood Test?

An allergy blood test is a laboratory examination that measures the immune system's response to specific allergens by detecting the presence of allergy-related antibodies in the blood. These antibodies, primarily Immunoglobulin E (IgE), are produced by the immune system when it encounters substances it wrongly perceives as harmful, triggering allergic reactions.

Unlike skin tests, which require direct exposure to allergens on the skin, blood tests evaluate the presence and level of IgE antibodies against various allergens in a small blood sample. These tests help identify allergic sensitivities to foods, environmental factors (like pollen or dust mites), insect stings, or medications.

What is it Used For?

Allergy blood tests serve several diagnostic and management purposes, including:

  • Identifying Allergens: Detecting specific allergens causing symptoms such as sneezing, itching, rashes, swelling, or asthma.

  • Diagnosing Complex Cases: Useful when skin testing isn’t possible due to skin conditions, medications interfering with skin reactivity, or risk of severe reactions.

  • Pediatric Testing: Blood tests can be preferable for young children who may not tolerate skin tests well.

  • Monitoring Allergy Treatments: Tracking changes in allergen sensitivity over time during immunotherapy.

    Pre-surgical Assessment: Screening for medication allergies before surgery.


    Allergy Blood Test Vs Allergy Skin Test: What’s The Difference?

    Both allergy blood tests and skin tests are common diagnostic tools, but they differ significantly:

    Aspect

    Allergy Blood Test

    Allergy Skin Test

    Procedure

    Blood draw to measure IgE antibodies

    Small allergen extracts pricked or injected on skin

    Time to Results

    Several days for lab processing

    Usually within 15-30 minutes

    Safety

    Safe for most patients, including those with skin issues or on antihistamines

    May cause localized or systemic allergic reactions

    Interference

    Less affected by medications like antihistamines

    Antihistamines and some medications must be stopped prior

    Number of Allergens

    Can test many allergens from a single blood sample

    Limited number tested at a time

    Sensitivity

    Generally less sensitive but more specific

    Highly sensitive but may have false positives

    Use Case

    Ideal for patients unable to undergo skin tests or with skin problems

    Commonly used for quick screening

    Ultimately, doctors may recommend one or both depending on clinical circumstances.

Your health care provider may order allergy testing if you have symptoms of an allergy. These include:

  • Stuffy or runny nose
  • Sneezing
  • Itchy, watery eyes
  • Hives (a rash with raised red patches)
  • Diarrhea
  • Vomiting
  • Shortness of breath
  • Coughing
  • Wheezing
A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
You don't need any special preparations for an allergy blood test.
There is very little risk to having an allergy blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

If your total IgE levels are higher than normal, it likely means you have some kind of allergy. But it does not reveal what you are allergic to. A specific IgE test will help identify your particular allergy. If your results indicate an allergy, your health care provider may refer you to an allergy specialist or recommend a treatment plan.

Your treatment plan will depend on the type and severity of your allergy. People at risk for anaphylactic shock, a severe allergic reaction that can cause death, need to take extra care to avoid the allergy-causing substance. They may need to carry an emergency epinephrine treatment with them at all times.

Be sure to talk to your health care provider if you have questions about your test results and/or your allergy treatment plan.

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  2. Asthma and Allergy Foundation of America [Internet]. Landover (MD): Asthma and Allergy Foundation of America; c1995–2017. Allergy Diagnosis; [updated 2015 Oct; cited 2017 Feb 24]; [about 6 screens]. Available from: http://www.aafa.org/page/allergy-diagnosis.aspx
  3. Asthma and Allergy Foundation of America [Internet]. Landover (MD): Asthma and Allergy Foundation of America; c1995–2017. Allergy Overview; [updated 2015 Sep; cited 2017 Feb 24]; [about 3 screens]. Available from: http://www.aafa.org/page/allergies.aspx
  4. Asthma and Allergy Foundation of America [Internet]. Landover (MD): Asthma and Allergy Foundation of America; c1995–2017. Allergy Treatment; [updated 2015 Oct; cited 2017 Feb 24]; [about 7 screens]. Available from: http://www.aafa.org/page/allergy-treatments.aspx
  5. Asthma and Allergy Foundation of America [Internet]. Landover (MD): Asthma and Allergy Foundation of America; c1995–2017. Drug Allergy and Other Adverse Reactions to Drugs; [cited 2017 May 2]; [about 6 screens]. Available from: http://www.aafa.org/page/medicine-drug-allergy.aspx
  6. Asthma and Allergy Foundation of America [Internet]. Landover (MD): Asthma and Allergy Foundation of America; c1995–2017. What Are the Symptoms of an Allergy?; [updated 2015 Nov; cited 2017 Feb 24]; [about 5 screens]. Available from: http://www.aafa.org/page/allergy-symptoms.aspx
  7. American College of Allergy Asthma & Immunology [Internet]. American College of Allergy Asthma & Immunology; c2014. Allergies: Anaphylaxis; [cited 2017 Feb 24]; [about 5 screens]. Available from: http://acaai.org/allergies/anaphylaxis
  8. Johns Hopkins Medicine [Internet]. The Johns Hopkins University, The Johns Hopkins Hospital, and Johns Hopkins Health System; Allergy Overview; [cited 2017 Feb 24]; [about 3 screens]. Available from: http://www.hopkinsmedicine.org/healthlibrary/conditions/adult/allergy_and_asthma/allergy_overview_85,p09504/
  9. Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2017. Total IgE: The Test; [updated 2016 Jun 1; cited 2017 Feb 24]; [about 3 screens]. Available from: https://labtestsonline.org/understanding/analytes/total-ige/tab/test
  10. Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2017. Total IgE: The Test Sample; [updated 2016 Jun 1; cited 2017 Feb 24]; [about 2 screens]. Available from: https://labtestsonline.org/understanding/analytes/total-ige/tab/sample/
Allergy Blood LabTest

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