Allergy blood tests
Many people in the UK are affected by allergy. There are lots of telltale signs to look for if you think you might be experiencing allergy symptoms. Signs such as frequent sneezing, itchy or watery eyes and a congested nose. You may experience problems when you eat certain foods. All of these symptoms could be related to allergies. But how do you know for sure? Read more about the different types of allergy symptoms.
One way a doctor may start the process of diagnosing allergy is referring you for allergy blood testing. In this article, we’re going to look at when an allergy blood test could be done and how the test is performed. We’ll talk about how accurate allergy blood testing is, and we’ll also explain what the test results can show.
What is an allergy blood test?
Allergy blood testing is the same as any other blood test: a small amount of your blood is sent to a lab for analysis.
Allergy blood tests can detect Immunoglobulin E (IgE) in your blood. IgE is an antibody produced by the immune system in connection with a reaction to protect us from outside intruders such as parasites.
When you’re allergic to for example pollen, certain foods or insect stings your immune system overreacts to the otherwise harmless substance and triggers the same defence mechanisms as against parasitic infections. The body produces IgE antibodies specific to the allergen it’s trying to fight. These antibodies tell cells in your body to release certain chemicals. And it is those chemicals that cause allergy symptoms.
Allergy blood tests identify and measure specific IgE antibodies in your blood. Since IgE antibodies are different depending on what they are reacting to, allergy blood testing can point to what allergens your body is reacting to.
Allergy blood tests show if you’re sensitised
Allergy blood testing can be the first step to finding out if you have an allergy. Think of the results of an allergy blood test as a sign of a suspected allergy rather than stand-alone proof. You basically get a risk profile of which allergen you might be allergic to.
When it comes to understanding how allergy blood testing works and how results are interpreted, it’s important to note that the presence of IgE antibodies in your blood does not necessarily mean you are allergic. It means that you are sensitised.
Sensitisation vs allergy
Sensitisation is the first step of developing allergy. Allergic reactions do not happen the first time you encounter an allergen. First, your immune system has to meet the allergen and build the specific IgE antibody against it. This process is called sensitisation.
If you’re allergic, the next encounter with the allergen might then trigger an allergic reaction. However, some people are sensitised and have specific IgE antibodies, but don’t experience any allergic reaction no matter how often they are in contact with the allergen.
That means an allergy blood test shows if you’re sensitised to a specific trigger. Not that you are necessarily allergic to it. Only in connection with your symptoms and medical history a doctor will be able to interpret the results in order to give a diagnosis of allergy.
When should allergy blood tests be done?
If your allergy symptoms are mild and the cause is obvious, your doctor will be able to offer advice and discuss treatment options with you. But you may be referred for allergy blood testing of a specific range of triggers if your allergy is more severe or it’s not clear what’s causing your symptoms.
Skin prick tests are one of the most common methods to test for allergy, but there are times when a blood test for allergy may be done along with skin prick tests or even instead of skin prick tests.
Allergy blood tests are especially useful if you have a skin condition. Or if you are taking certain medications that could interfere with the skin prick test results. Allergy blood testing may also be used if the results from skin prick tests did not give clear results.
How are allergy blood tests performed?
Many of us will have had a blood test at some point in our lives. A small amount of your blood is taken from a vein and sent to a lab for analysis. Collecting a blood sample is usually only temporarily uncomfortable.
Your blood sample will be sent to a laboratory and tested against the allergens your doctor has chosen for the test. When your allergy blood test results are ready you will need to go back to your doctor to discuss them.
How accurate are allergy blood test results?
Overall, the accuracy of blood tests for allergy is high. Blood tests are evolving all the time and getting more precise. Some blood tests are now able to give results for individual components of a single allergen.
What to do after allergy blood testing
Knowing exactly what you are allergic to means you’re better equipped to manage your allergy symptoms. You’ll be able to discuss your treatment options with your doctor and make decisions that are right for you.
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1399CCb October 2019