An estimated 1 in 5 people in the US suffer from allergy or asthma symptoms and around 4 million workdays are lost each year as a result of hay fever. Allergies do not need to affect your quality of life, but whether you react to pollen, certain foods or pets, it’s important to be aware of any substances your body responds to. Luckily, allergy tests today, are not only convenient but also accurate in predicting potential allergy sufferers.
Why get tested?
Once you know what you’re allergic to, you can work together with your doctor or healthcare provider to create a plan of lifestyle changes that will enable you to avoid potential allergens. Unfortunately, there are not yet any cures for allergies but there are many precautionary steps such as allergy shots, medications (both over-the-counter and prescription) or even immunotherapy that can help prevent or control allergic reactions. Your doctor will also be able to give you advice on what to do should you experience an allergic reaction.
How do I get tested?
Despite a large array of at-home allergy testing kits, you should only get tested at your local doctor or medical centre. At-home testing kits may be unreliable and are therefore not recommended to base a diagnosis on. When you visit your doctor for an allergy test, you will first have a personal medical history taken, as well as a family history; the length of time this takes will depend on the level of detail your doctor requires. Then there are various ways to get tested for allergens with the three most common being a patch test, a skin prick test and a blood test.
● Patch test
Contact dermatitis is a skin allergy that occurs when your body comes into contact with certain allergens. For example, some people can get an itchy rash when using specific washing detergents or wearing certain jewellery. These types of allergens can be tested for by wearing a small pad, or patch, that contains an allergen and wearing this patch 24 to 72 hours. Typically between 25 to 150 small patches can be worn at a single time. Patches are removed on a subsequent visit to your doctor and follow-up appointments will monitor the area of skin tested for any cases of allergic reactions. The need to avoid water (including showering) or vigorous exercises and stretching make the patch test inconvenient for some although it is a reliable allergy testing method.
● Skin Prick Test
The skin prick test is another way of determining contact dermatitis but it can also be used to identify food allergens, airborne allergens (such as pollen, mould and pet dander), and any allergies to medications. The test is carried out by dropping a small solution containing a suspected allergen onto the skin and scratching the surface of the skin with a needle to allow the solution to penetrate through. If the skin becomes reddened with a raised, itchy area this is usually a sign of an allergic reaction.
● Blood Tests
Even though most allergens are in fact harmless, an allergic reaction is the body’s way of dealing with what it perceives as a threat. When an allergic reaction occurs in a person, certain substances called antibodies are produced to try and eliminate this ‘threatening’ allergen. A blood test can be used to analyse the presence of these antibodies and around 650 different allergens can be tested. Blood tests, however, may not be as sensitive or accurate as skin tests and while skin tests are preferred a blood test is normally reserved for those who are unable to take the patch or skin prick tests.
The enzyme-linked immunosorbent assay (ELISA) is the most common type of blood test used to detect allergies. This measures the level of a certain antibody (immunoglobulin E, IgE) that the body produces in response to exposure to certain allergens as the level of IgE is often higher in people with allergies. Interpreting the results of a blood test is very important, however, as high number of ‘false positives’ can occur - that is, you present positive in a test for an allergy to a certain substance without actually having an allergy. This is common in food allergen testing. Eating a lot of a certain food the day of the blood test may mean you have a higher than normal level of IgE in your blood that day, but it doesn’t mean you have an allergy for that food type. It is important for your doctor to carry out a complete and up-to-date history at the time of the test to be able to determine true allergies from false positives.
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