What allergies can a blood test determine
What is an allergy blood test?
Allergies are a common and chronic condition that involves the body’s immune system.
Normally, your immune system works to fight off viruses, bacteria, and other infectious agents. When you own an allergy, your immune system treats a harmless substance, love dust or pollen, as a threat. To fight this perceived threat, your immune system makes antibodies called immunoglobulin E (IgE).
Substances that cause an allergic reaction are called allergens. Besides dust and pollen, other common allergens include animal dander, foods, including nuts and shellfish, and certain medicines, such as penicillin.
Allergy symptoms can range from sneezing and a stuffy nose to a life-threatening complication called anaphylactic shock. Allergy blood tests measure the quantity of IgE antibodies in the blood.
A little quantity of IgE antibodies is normal. A larger quantity of IgE may mean you own an allergy.
Other names: IgE allergy test, Quantitative IgE, Immunoglobulin E, Entire IgE, Specific IgE
If you ponder you own an allergy, tell your GP about the symptoms you’re having, when they happen, how often they happen and if anything seems to trigger them.
Your GP can offer advice and treatment for mild allergies with a clear cause.
If your allergy is more severe or it’s not obvious what you’re allergic to, you may be referred for allergy testing at a specialist allergy clinic.
Find your nearest NHS allergy clinic
The tests that may be carried out are described on this page.
In a few cases, a test called a food challenge may also be used to diagnose a food allergy.
During the test, you’re given the food you ponder you’re allergic to in gradually increasing amounts to see how you react under shut supervision.
This test is riskier than other forms of testing, as it could cause a severe reaction, but is the most precise way to diagnose food allergies.
And challenge testing is always carried out in a clinic where a severe reaction can be treated if it does develop.
Skin prick testing
Skin prick testing is one of the most common allergy tests.
It involves putting a drop of liquid onto your forearm that contains a substance you may be allergic to.
The skin under the drop is then gently pricked.
If you’re allergic to the substance, an itchy, red bump will appear within 15 minutes.
Most people discover skin prick testing not particularly painful, but it can be a little uncomfortable. It’s also extremely safe.
Make certain you do not take antihistamines before the test, as they can interfere with the results.
Patch tests are used to investigate a type of eczema known as contact dermatitis, which can be caused by your skin being exposed to an allergen.
A little quantity of the suspected allergen is added to special metal discs, which are then taped to your skin for 48 hours and monitored for a reaction.
If you own a suspected food allergy, you may be advised to avoid eating a specific food to see if your symptoms improve.
After a few weeks, you may then be asked to eat the food again to check if you own another reaction.
Do not attempt to do this yourself without discussing it with a qualified healthcare professional.
Blood tests may be used instead of, or alongside, skin prick tests to assist diagnose common allergies.
A sample of your blood is removed and analysed for specific antibodies produced by your immune system in response to an allergen.