The immunoglobulin E (IgE) blood test, also called the IgE test, is an important tool for diagnosing allergies. IgE is a protein made by the immune system that plays a major role in allergic reactions. When a person is exposed to an allergen like pollen, their immune system makes IgE antibodies that react to these allergens. The IgE blood test measures the level of IgE antibodies in the blood to specific allergens. A higher-than-normal level indicates an allergy. This test helps doctors determine what substances a patient is allergic to so they can provide guidance on avoiding allergy triggers and managing symptoms. The rest of this article will go over the IgE test in more detail – what’s involved, how to prepare, results interpretation, and how it fits into allergy diagnosis along with skin prick testing.
What is IgE in Blood Test?
Immunoglobulin E (IgE) is a type of antibody made by the immune system. Antibodies defend the body against things that could cause disease or infection, like bacteria, viruses, and allergens. IgE antibodies trigger allergic reactions. When an allergen enters the body, IgE antibodies recognize it and tell the immune system to release histamine. Histamine causes allergy symptoms like itchy eyes, sneezing, or skin rashes.
Why do I Need an Allergy Blood Test?
A total IgE blood test measures the level of IgE antibodies in the blood. This allergy testing helps diagnose allergies and see how severe they may be. Doctors may order an IgE test if someone has symptoms of an allergy but they don’t know what causes it. Some reasons for getting an allergy blood test are:
- Recurring allergy symptoms with an unknown cause
- Reactions to insects, medications, or latex
- Asthma that could be linked to allergies
- Eczema or skin reactions that seem allergy-related
The test reports the amount of IgE in international units per milliliter (IU/mL). Normal IgE levels depend on age:
Normal IgE Levels by Age
| Age Group | Normal IgE Level |
| Children under 5 years | less than 60 IU/ml |
| Children 5-9 years | less than 90 IU/ml |
| Children over 9 years | less than 200 IU/ml |
| Adults | less than 100 IU/ml |
Higher than the Immunoglobulin E normal range means you may have allergies. Very high levels over 1000 IU/mL often indicate an allergy, immune system disorder, or parasite infection.
How the IgE Blood Test is Performed
To do a total IgE blood test, a healthcare provider will:
- Clean the skin and tie a tourniquet around the upper arm to make the veins easier to see
- Insert a small needle into a vein in the inner elbow or back of the hand
- Collect a sample of blood into a tube
- Remove the needle and bandage the puncture site
The blood sample is sent to a lab where it is tested to measure the level of IgE antibodies. Higher than normal levels likely mean an allergy is present.
Preparing for the IgE Blood Test
No special preparation is needed for this test. Patients can eat and drink normally before having blood drawn. It’s important to tell the provider about any medicines or supplements taken recently, as some may affect test results.
Risks and Side Effects
An IgE blood test is safe with few risks. Some people may feel brief pain or dizziness when the needle goes in. Rarely, excess bleeding, fainting, infection, or blood vessel injury can occur. Tell the provider promptly about any swelling, redness, drainage, dizziness, or other concerning symptoms after the test.
IgE Blood Test Results Explained
The results of an IgE blood test are given in International Units per milliliter (IU/mL).
IgE Blood Test Normal Range
In most labs, a normal IgE blood level is between 30 and 350 IU/mL for adults and teens and between 2 and 200 IU/mL for children under age 12. If your IgE level is within the normal range, it usually means you don’t have an allergy. However, some people can still have allergies even if their IgE levels are normal.
IgE Blood Test High Levels
If your IgE level is higher than the normal range, you may have an allergy. Levels between 350-2,000 IU/mL often mean a mild to moderate allergy. Levels above 2,000 IU/mL indicate a more significant allergy. High IgE levels can be caused by allergies to foods, animals, dust mites, molds, insect stings, latex, some medicines, and other substances.
Low IgE Blood Test Levels
An IgE level below the normal range is rare but can happen. Potential causes include certain autoimmune disorders, immunodeficiency diseases, or certain medicines like corticosteroids. Low levels usually don’t cause symptoms or health issues. More testing may be needed to determine if there is an underlying condition.
Other Allergy Tests
There are a few other tests that can help diagnose allergies:
- Skin prick test: Drops containing common allergens are placed on the skin, which is then pricked with a needle. If a raised, itchy bump forms, it may indicate an allergy.
- Patch test: Potential allergen extracts are taped onto the skin for 48 hours. An itchy red rash may signify an allergy.
- Elimination diet: Foods suspected of causing a reaction are removed from the diet to see if symptoms improve. Foods are then reintroduced one at a time.
Comparing IgE Blood Test to Other Allergy Tests
The IgE blood test has some advantages over other allergy testing methods:
- It is not invasive like skin or patch testing. Just a blood sample is needed.
- It can test for many allergens at once from one blood sample. Other tests usually check for reactions to single allergens.
- It can measure the level of IgE antibodies quantitatively. Other allergy tests record only yes/no reactions.
- Results don’t vary on the patient’s skin condition or medication use like skin testing.
Managing Allergies Based on Total IgE Blood Test Results
If you’ve had a blood test that measures your immunoglobulin E (IgE) level, the results can help guide treatment for allergies. Higher IgE levels usually mean you have more allergies. Here’s an overview of ways to manage allergies depending on your test results:
Lifestyle Changes
If your IgE level is only slightly elevated, simple lifestyle changes may be enough to control symptoms. Things like avoiding triggers, using air filters, washing bedding regularly in hot water, and managing stress can help reduce allergic reactions.
Medications
If lifestyle changes aren’t enough, over-the-counter or prescription medications may be recommended depending on your symptoms. Common options include antihistamines like cetirizine (Zyrtec) or loratadine (Claritin), nasal corticosteroid sprays like fluticasone (Flonase), and eye drops for itchy eyes.
Immunotherapy
If your IgE level is very high, or if medications don’t provide enough relief, immunotherapy or “allergy shots” may be an option. This treatment involves getting injections of small amounts of allergens to desensitize your immune system over time. Studies show immunotherapy can significantly reduce symptoms long-term.
What Affects the IgE Blood Test Cost?
An immunoglobulin E (IgE) blood test checks for IgE antibodies to identify allergies. Several factors impact the cost of this test:
- Type of healthcare provider: An IgE test ordered by an allergist at a specialized facility often costs more than one ordered by a general practitioner.
- Insurance: Those with insurance pay less out-of-pocket than the uninsured. Many plans cover allergy testing, but copays and deductibles still apply.
- Testing lab: National labs charge more than local hospital or clinic labs. Prices range widely between labs.
- Number of allergens tested: Testing a panel of common allergens costs less per item than testing single allergens. Panels help identify unknown triggers.
So the total IgE test cost varies widely but often falls in the $100 to $500 range based on the above factors. Talk to your provider so you know the potential cost beforehand based on your specific testing needs. Understanding the cost breakdown allows you to budget accordingly.
Frequently Asked Questions About IgE Tests
Is High IgE Levels Dangerous?
Having very high IgE levels can mean your body reacts strongly to allergens. This can cause severe allergic reactions. But for most people, slightly elevated levels are not dangerous.
How Often to Get Tested?
Most doctors recommend testing every 2-3 years if you have seasonal allergies. For food or pet allergies, yearly testing can help track changes.
Do IgE Levels Change Over Time?
Yes, your IgE levels can go up or down over months/years as allergies get better or worse. Kids often outgrow allergies. Adults can develop new ones. Retesting checks these changes.
How Accurate Is the IgE Blood Allergy Test?
No test is 100% accurate, but IgE blood tests can help diagnose allergies when used along with your medical history and allergy skin tests. An allergy specialist can interpret your results and determine if you have allergies. They may order additional tests to confirm or rule out specific allergies.
Conclusion
The IgE blood test is an important tool for evaluating allergies. It measures levels of IgE antibodies that react to specific allergens. High IgE levels indicate an allergy and can help predict if symptoms will be more severe. Low levels may mean milder or no allergy. This test reveals what substances trigger an allergic response in a person, allowing proper diagnosis. It also checks if allergy treatments are working by comparing before and after IgE levels. While a useful indicator, every individual has a unique health profile. For personalized advice on managing your allergies, consult an allergist or doctor, who can tailor testing and treatment based on your needs. Working with a professional is key to improving allergy symptoms long-term.
