Allergies can have a negative impact on your daily life, whether it involves battling pollen, dust mites, or certain foods. With over 50 million individuals in the United States alone affected by allergies, testing for allergies is vital to taking care of yourself and regaining control over your wellness(1).
Today, we’re examining blood allergy tests and their role in helping you identify your allergies. How accurate are blood allergy tests? What information do they provide? We’re answering these questions and showing you the easiest way to test yourself for over 40 common allergens.
Types of Allergy Tests
Before we dive into answering the question, “How accurate are blood allergy tests?” let’s take a look at the most common types of allergy tests you may encounter. It’s important to understand that any test alone does not diagnose an allergy. Testing needs to be considered in the context of a patient’s history of symptoms.
Skin-prick tests (SPT): This test involves placing a small amount of allergen extracts on the skin's surface and then pricking or scratching the skin to allow the allergens to enter. If a raised bump or redness appears at the test site, it indicates that a patient is sensitized to that allergen.
Patch Test: Mostly used to diagnose allergies to products that come into direct contact with your skin and cause a rash, known as contact dermatitis. . Patch tests involve applying allergen-containing patches to the skin for a period of time. Reactions, such as redness or irritation, indicate a sensitivity to the tested allergens.
Intradermal tests (IDT): A type of allergy test that involves injecting a small amount of allergen extract just beneath the skin's surface to assess the body's immune response, typically used when skin prick tests yield inconclusive results or to detect allergens with low sensitivity thresholds (the amount of an allergen that can be tolerated without producing a reaction).
Blood allergy test (specific IgE test): Blood tests measure the levels of allergen-specific antibodies (IgE) in the bloodstream. A higher level of IgE antibodies to a particular allergen suggests sensitivity to that substance.
Taking a Blood Allergy Test
There are many types of allergy tests available, but skin testing and blood allergy testing are likely to identify the most clinically important allergens.
Two types of blood allergy tests are serum allergen-specific IgE concentrations and Immunoglobulins blood tests (IgG).
Serum allergen-specific IgE concentrations: The first of these blood allergy tests. This analyzes the levels of specific IgE antibodies against various allergens in the blood. You can take this type of test with our at home allergy test to get results for 40 common indoor and outdoor allergens. You may also take an ImmunoCap IdE test like those available through Quest Diagnostics or Labcorp. Make sure your test is from a CLIA-certified lab to ensure accuracy, precision, and reliability in their testing. Not all tests are created equal and may provide inadequate results.
Immunoglobulins blood test (IgG): This type of blood test is used to analyze the IgG antibodies to specific foods present in your blood. At this time, IgG antibodies are not considered reliable for identifying food allergies, intolerance, or sensitivities. Most people produce IgG antibodies after eating food and it’s not recommended as a diagnostic tool.
Pros of Blood Allergy Tests
Blood allergy tests, also known as specific IgE tests or serologic allergy tests, offer several benefits that contribute to their widespread use. These benefits largely stem from their accuracy and convenience:
Wide range of allergens: Blood tests can screen for many different types of allergens, including pollen, dust mites, pet dander, and specific food allergens such as nuts, dairy, and shellfish. This comprehensive testing capability is particularly useful for individuals with multiple sensitivities.
Objective results: Blood tests provide quantitative data on the level of allergen-specific antibodies (IgE) present in the bloodstream. This objective measurement helps healthcare professionals make informed diagnostic and treatment decisions.
No need to stop medications: Unlike skin prick tests, blood allergy tests do not require patients to discontinue antihistamines or other medications that might affect the results. This makes them a viable option for anyone who relies on those medications to manage their allergy symptoms.
Less invasive and safer: The process of drawing blood is less invasive than skin prick tests, making blood allergy tests more comfortable for people, including children and those with a fear of needles. It also eliminates the risk that a skin prick test could yield a large reaction.
Cons of Blood Allergy Tests
Blood allergy tests have numerous advantages, but there are a couple of limitations to be aware of:
Potential false negative or positive results: Sometimes a test may be negative even though there is a strong history to support an allergy, or be positive without a history of a reaction. Remember, allergy blood test accuracy is reliant upon getting a full allergy history of reactions and the two together are what diagnoses an allergy.
Processing time: Blood allergy test accuracy requires it to be sent out to a lab for analysis. This means it takes a little more time than other types of allergy tests to get the results.
Some tests limit Information on severity: Similar to other types of allergy tests, certain blood tests do not provide information about the severity of allergic reactions. While they identify sensitivity to certain allergens, more basic tests may not assign levels of potential severity.
How accurate are blood allergy tests provided by Nectar compared to others? Our at home allergy test returns information with an intensity value between 0-255 for each allergen tested. Whatever range you fall into is categorized into a “Class,” which indicates how severe your sensitivity to an allergen might be. Each “Class” falls into a “Reactivity Level” that ranges from “Very Low” to “Very High,” providing you with more information about which allergens affect you most.
How Accurate Are Blood Allergy Tests?
With so many types of tests available, it makes sense to wonder “Are blood allergy tests accurate?” Blood allergy tests (IgE tests) are generally considered accurate for identifying allergen sensitivities. On average, allergy blood test accuracy demonstrates sensitivity rates ranging from 70% to 90%, and specificity rates ranging from 40% to 100%(2).
While they offer a wide range of allergen screening and objective results, it's important to interpret the results in conjunction with clinical symptoms because elevated IgE levels don’t always correlate directly with noticeable allergic reactions.
Allergy Blood Test Accuracy Factors
The measurement of how accurate are blood allergy tests varies based on several factors:
Sensitivity and specificity: Blood allergy test accuracy is often expressed in terms of sensitivity (the ability to correctly identify someone with a condition) and specificity (the ability to rule out a condition). Remember though that for allergies, a diagnosis requires interpretation of the blood allergy test or skin test PLUS a clinical history. A test result alone does not diagnose an allergy.
Allergen source: The results of blood allergy tests can be influenced by the type of allergen being tested. Some allergens, like those found in certain foods, can produce cross-reactivity(3).
Age and immune response: Age plays a role in allergy blood test accuracy. Young children may have less reliable results due to their developing immune systems. Additionally, people with compromised immune systems may produce inaccurate responses.
Testing method and laboratory quality: Blood allergy test accuracy is also dependent on the testing method used and the quality of the laboratory conducting the analysis. Choosing a reputable lab and utilizing up-to-date testing techniques can enhance the accuracy of results.
It’s also possible your blood allergy test may return showing no results for allergies. If this happens, you may be part of the 30-50% of patients who suffer from allergy-like symptoms including congestion, runny nose, sneezing, and postnasal drip may not have allergies. This is a condition called non-allergic rhinitis.
Note: The Nectar partner laboratoryis CLIA and CAP-certified, meaning they follow high-quality laboratory practices. CAP requirements meet or exceed CLIA compliance requirements, and the comprehensive standards ensure that test results are highly accurate.
Are blood allergy tests accurate? They are generally considered to be very accurate. It’s important to get your test from a reputable source partnering with a high-quality laboratory to ensure allergy blood test accuracy. Knowing which allergens you’re reactive to — along with your medical history and geographical location — will help determine a custom allergy treatment so you can get back to feeling your best.
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