Parents that suspect that their child may have allergies have two choices. Their child’s doctor may suggest a blood test, or a skin test. New information suggests that the skin testing may not be as accurate as it once was believed to be.
I am someone who has tons of allergies. When I was a teenager, I was given a blood test that was used to determine some of the things that I am allergic to. Later, my allergist suggested that I take what was called a “skin test”, because it was considered to be a better diagnostic tool.
I can tell you from first hand experience that undergoing this type of test is uncomfortable at best, and painful at worst. There is the chance that the test itself can cause a person to experience an allergic reaction to something.
It involves using the skin on a person’s back or arms. A solution containing each suspected allergen is injected (subcutaneously) onto a place under the skin. The allergist keeps track of which allergen was placed where. Time passes, and when a certain amount of time has passed, the allergist measures how large a welt appeared at each injection site. It is extremely difficult to resist scratching at those areas.
This was decades ago. Much of what showed up on those tests indicated that I was severely allergic to quite a few different types of allergens. In the years since then, I have discovered more things that I am allergic to.
A clinical report from the American Academy of Pediatrics (AAP) shows that skin testing, which is really called allergen-specific immunoglobulin E (IgE) testing, is not always an equivalent to an clinical diagnosis. In other words, the report showed that just because a child shows a sensitization to an allergen that has been injected underneath his skin, it doesn’t necessarily mean that the child has an allergy.
The report said that doctors should select appropriate allergy testing. For example, a child who has never shown any allergic reaction after eating eggs doesn’t need to have a test done to see if she is allergic to eggs. Any results shown from a skin test need to be interpreted based upon the context of the child’s medical history, and the allergy symptoms that he or she presented in the past. Without that consideration, the results may be interpreted in an inaccurate way.
There are certain types of allergens that are not appropriate to use a skin test for. Asthma can be diagnosed without the use of a skin test. A doctor can use national guidelines that test for allergens to dust or mold, instead. There isn’t any evidence that a skin test will identify allergies to specific foods. You cannot use a skin test to learn if a child is allergic to certain types of drugs, or is allergic to insect venom. Latex allergies are another example that cannot be entirely determined by skin testing alone.
This is not to say that skin testing should never be used, or that it is always inaccurate. Parents need to realize that a blood test, or serologic test, can do much of what your doctor wants to preform a skin test to determine. In general, a skin test provides more immediate results, and is less expensive, than blood testing for allergies will be.
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