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Allergy Blood Test

IgE allergy test

The Allergy blood test is a comprehensive blood test that can help identify the specific causes of your allergies. How is it done?

Allergy blood test or IgE allergy test is a test that is used to aid in the diagnosis of allergies; and, on occasion, to assess the efficacy of immunotherapy (desensitization) treatment.


What is an allergy blood test?

Allergies are a familiar and chronic disorder that affects the body’s immune system. Your immune system usually works to protect you from viruses, bacteria, and other infectious agents. When you suffer from an allergy, your immune system perceives a non-threatening substance, such as dust or pollen, as a threat. The immune system produces antibodies known as immunoglobulin E. (IgE) to combat this potential threat.

Allergens are substances that cause an allergic reaction. Other common allergens besides dust and pollen include animal dander, foods such as nuts and shellfish, and certain medications such as penicillin. Allergy symptoms can vary from sneezing and a stuffy nose to a potentially fatal condition known as anaphylactic shock. Allergy blood tests assess the presence of IgE antibodies in the blood.

It is normal to have a small amount of IgE antibodies. A higher level of IgE may indicate that you have an allergy. Allergy blood tests typically screen for at least ten of the most common allergy triggers, such as dust, pet dander, trees, grasses, weeds, and molds specific to your location. They are also extremely useful in determining food allergies.

Allergy blood tests, also known as immunoassay tests, include the following:

  • Enzyme-linked immunosorbent assay (ELISA) (ELISA, or EIA).
  • Test for radioallergosorbent (RAST).
This test is also known as IgE allergy test, Quantitative IgE, Immunoglobulin E test, Total IgE, Specific IgE.

How is this test used?

IgE Test
total IgE Test, Allergy

The allergen-specific IgE antibody test is a blood test used to diagnose an allergy to a specific substance or substances in a person who has acute or chronic allergy-like symptoms. This is especially true if the symptoms are recurring and appear to be linked to triggers, such as exposure to specific foods or environments, and if other family members have allergies.

Other allergy tests may be conducted by exposing a person to various substances while under medical supervision. However, the usefulness of these tests can be influenced by skin conditions such as severe dermatitis or eczema, as well as medications such as antihistamines and some antidepressants.

With some tests, there is also the possibility of severe reactions, such as anaphylaxis, which can be fatal. In these cases, the allergen-specific IgE antibody test, which is performed on a blood sample, may be ordered as an alternative.

The allergen-specific IgE antibody test may also be used to track the progress of immunotherapy (desensitization) or to determine whether a child has outgrown an allergy. Typically, the health care practitioner will interpret the test results in light of a person’s symptoms and any other allergy tests that are being performed.

“Read also: ALT Blood Test


When is the IgE allergy test ordered?

When a person exhibits signs or symptoms suggestive of an allergy to one or more substances, one or maybe more allergen-specific IgE antibody tests may be needed. Among the signs and symptoms are:

  • Hives.
  • Dermatitis.
  • Eczema.
  • Itchy red eyes.
  • Coughing, sneezing, and nasal congestion.
  • Asthma.
  • Itching and tingling sensations in the mouth.
  • Throat blockage.
  • Breathing difficulties.
  • Vomiting and diarrhea as a result of abdominal pain.

A test could also be ordered from time to time to evaluate the efficacy of immunotherapy or determine whether a child has outgrown an allergy.


What happens during a blood test for allergies?

Allergy Blood Test
IgE allergy test results, ige allergy test normal range

A medical professional will use a small needle to take a blood sample from a vein in your arm. Just after needle insertion, a sample of blood is collected in a test tube or vial. You could feel a slight sting when the needle is inserted or removed. This usually takes under five minutes.


Is there anything I need to do to prepare for the test?

An allergy blood test does not necessitate any special preparations.


Are there any risks in doing this test?

An allergy blood test carries minimal risk. You may experience minor pain or bruising where the needle was inserted, but most symptoms will subside.


IgE Allergy Test results

Allergy
ige allergy test results, ige allergy test normal range,

If your total IgE levels are elevated, you most likely have an allergy. It does not, however, reveal what you are allergic to. A specific IgE test will aid in the identification of your allergy. If your results show that you have an allergy, your doctor may refer you to an allergy specialist or recommend a treatment plan.

Your treatment strategy will be determined by the type and severity of your allergy. People who are at risk of anaphylactic shock, a severe allergic reaction that can result in death, must take extra precautions to avoid the allergen. They may need to carry an epinephrine emergency treatment with them at all times.

Negative results refer that the patient does not have a true allergy, defined as an IgE-mediated response to the allergens tested.

Allergy blood test results must be interpreted with caution. False negatives and false positives are possible. Even if an IgE test comes back negative, there is still a chance that a person has an allergy. Similarly, if a specific IgE test is positive, a person may or may not ever have a physical allergic reaction to that substance.


Is there any other info I should be aware of?

Other blood tests, such as a total IgE level or a complete blood count (CBC) and white blood cell differential, may be used by a doctor to look for an indirect indication of an ongoing allergic process (specifically eosinophils and basophils). Increased levels of these tests may indicate an allergy, but they may also be elevated for other reasons.

An IgE skin test is another method for detecting allergies, as it measures IgE levels and looks for a reaction on the skin. An IgE skin test may be ordered instead of, or in addition to, and IgE allergy blood test by your doctor.


What other allergy testing options are there?

An allergist or dermatologist will perform skin prick or scratch tests, intradermal tests, patch tests, and oral food challenges. These tests can be subjective and are influenced by factors such as allergen dose, test administration, and interpretation of results.

Your doctor may also try removing foods from your diet and then reintroducing them to determine what you are allergic to. These tests must be performed under close medical supervision, as a life-threatening anaphylactic reaction is possible.


Will my allergies ever clear up?

Although some allergies are outgrown in children, they are not usually outgrown in adults. Allergies that cause the most severe reactions, such as anaphylaxis caused by peanuts, usually do not go away. The safest course of action is to avoid the allergen and prepare for accidental exposure with medications such as antihistamines and portable epinephrine injections. Immunotherapy can help reduce symptoms for some unavoidable allergies. Still, it will not work for food allergies, and the treatment, which typically consists of years of regular injections, may have to be continued indefinitely.


How reliable are allergy blood tests?

Although skin prick tests are more sensitive than blood tests, both are considered accurate for allergy diagnosis. The accuracy of a blood test vs a skin prick test can be affected by several factors, including:

  • People with darker skin may have difficulty interpreting skin-prick test results.
  • Medication has an effect on skin prick tests, but it does not affect blood tests.
  • Blood tests are preferred over skin tests when the patient is very young or uncooperative, has had anaphylaxis to a portion of food, or has extensive eczema, and there is no good place to test on the skin.

Benefits and Drawbacks of Allergy blood test

The following are some of the benefits of allergy blood tests:

  • It can be done at any time, regardless of whether or not you are taking any medications.
  • Unlike skin testing, only one needle stick is required; this may be more appealing to people afraid of needles. Allergy blood testing is the preferred test for infants and very young children.

The following are some disadvantages of allergy blood tests:

  • It is more expensive than skin testing, and many health insurance companies do not cover allergy blood tests.
  • It may be less sensitive than a skin allergy test.
  • Because a blood sample must be sent to a laboratory for analysis, results can take days or weeks; skin testing provides immediate results.

You should always discuss your Allergy blood test results with your doctor.

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