Allergy Testing for Kids

When Should Kids Have Allergy Testing Done and For What Reasons?

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Sometimes children need allergy testing, just as adults, emphasized by the fact many allergy medications are approved for use in infants as young as six months of age.  What should you know about the types of testing available?

Allergy Skin Testing

Many parents believe that their kids have to reach a certain age, like when they start school, before they can get tested for allergies. This is mostly because they think allergy testing, especially skin testing, is painful.

  It's generally thought that children as young as 1 month can safely undergo allergy skin testing.  This opinion is upheld by both the American Academy of Pediatrics and the American Academy of Allergy, Asthma, and Immunology.

Allergy Blood Tests

Allergy blood tests are in general less sensitive than skin tests, but have an advantage in some situations.  They are helpful for children who are age 2 or younger since these children have less skin reactivity to skin tests. They also tend to be more useful when it comes to evaluating food allergies.  Allergy blood tests don't carry any risk of allergic reaction as do skin tests and do not require parents to stop allergy medications before doing the test.  Yet another advantage is that these tests can be ordered by your pediatrician, rather than having to make a separate appointment with an allergist.. There are 2 types of allergy blood tests that are commonly done.

RAST - The radioallergosorbent test or RAST, such as the Immunocap, is one method of testing, but is fairly outdated relative to other methods.  Some physicians, however, still do this testing.  The downside to RAST testing is that instead of seeing the small hives from skin testing that means that you are allergic to something, with the blood allergy test, you are simply measuring antibody levels and low levels may not always mean that your child is truly allergic to that allergen.

So RAST tests have to be carefully interpreted by your doctor or you might end up being told that your child is allergic to everything, simply because he has low levels of antibodies to a lot of different things, which can be normal.  In other words, there can be false positives.

ELISA test - The enzyme-linked immunosorbent assay (ELISA) has largely replaced the RAST blood test for allergies.  It has the advantage over RAST of avoiding the radioactivity and being more sensitive.  As with RAST, this test may be able to distinguish food allergies better than would skin testing.

 When Should Kids Have Allergy Testing?

After deciding what type of allergy testing may be best, it's time to decide when.  As noted above, children can have allergy testing even as infants.  The question comes down to what for and why you plan on having your child tested.  Think about the following reasons, and how allergy testing - and thus knowing the source of his allergies - might help.

Reasons to Have Your Child Tested for Allergies

Just because your child has allergies doesn't mean he needs allergy testing, especially if his allergy symptoms are easily controlled with allergy medicines, such as Clarinex, Claritin, Singulair, or Zyrtec or by avoiding common allergy triggers, even if you aren't sure what specifically triggers your child's allergies.

  Are your child's seasonal allergies bad enough that you would consider allergy shots?

There are several reasons beyond the obvious for which you may want your child tested.  These can include:

  • Food allergies - In infants and toddlers food allergies are a common reason to consider testing.
  • Eczema (atopic dermatitis) - Ezcema along with food allergies is a common reason to do allergy testing in young children, especially if your child has poorly controlled eczema.
  • Asthma - Knowing what triggers your child's asthma is sometimes helpful in controlling his symptoms.
  • Recurrent colds or chronic sinus infections - If your child always has a runny nose or has recurrent sinus infections, it may be hard to know whether he is getting recurrent infections or if instead, he is coping with allergies.  This can be especially hard to distinguish if he is in daycare, and exposed to a lot of infections.

Kids and Food Allergies

As noted earlier, allergy blood tests are a good way of testing for food allergies, and in addition to identifying foods that your child may be allergic to, can give you an idea of the degree of allergy she has by testing for the amount of allergic antibody.

Instead of allergy testing, and if the possible allergies you are trying to evaluate are not those due to nuts and shellfish, trying an elimination diet can sometimes give answers without the discomfort or expense of allergy testing.

Sources:

American Academy of Pediatrics. Healthychildren.org. Skin tests – the mainstay of allergy testing. https://www.healthychildren.org/English/health-issues/conditions/allergies-asthma/Pages/Skin-Tests-The-Mainstay-of-Allergy-Testing.aspx

Burks, W. Diagnostic evaluation of food allergy. UpToDate. Updated 10/20/15. http://www.uptodate.com/contents/diagnostic-evaluation-of-food-allergy

American College of Allergy, Asthma, and Immunology. Allergy Testing in Children and Infants. Accessed 04/13/16. http://acaai.org/allergies/treatment/allergy-testing/children

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