Allergy Testing in Children and Infants
Few young people like getting a test or going to the doctor. When an allergy is suspected in a child, both of these stressful tasks are combined and can cause quite a bit of dreadfor parents and children alike.
Knowing what to expect when you take your child for an allergy test may lessen appointment-day anxiety. Below is information about the common methods allergists use to test infants and children for allergies. Use it as a reference to prepare youngsters for a visit to the allergist.
When to Schedule an Allergy Test?
Allergies in infants and children are common. In fact, allergy-related disorders are among the leading chronic diseases diagnosed in children. According to one study, 4 percent to 6 percent of children have food allergies, 8 percent to 10 percent have asthma, and 15 percent to 25 percent have allergic rhinitis (hay fever). Children with allergies miss hundreds of thousands of school days every year.
For infants and children experiencing the following symptoms or conditions, an allergy test may determine if the problem is caused by specific allergens:
- Food, insect sting, or medication reaction
- Skin rashes (atopic dermatitis or eczema)
Other indicators of an allergy can be cold-like symptoms that last for more than a week and occur around the same time every year, as well as coughing and wheezing, especially at night, which might be allergic asthma caused by an indoor allergen.
What Allergy Testing Methods Are Used?
Parents and caretakers who suspect that a child has an allergy can visit an allergist, who will choose an appropriate methodor combination of methodsto make the diagnosis. A correct allergy diagnosis is important because it allows allergists to choose the best therapeutic intervention, such as tactics to help children avoid the allergen, medication, diet modification or immunotherapy allergy shots.
The allergists diagnostic process, which usually takes place in the allergists office, typically involves taking the childs detailed medical history and the family history of allergy or asthma, a physical exam, and allergy sensitivity testing.Allergists mostly use skin, blood, or elimination tests to detect allergens.
Skin tests. Immediate-type hypersensitivity skin tests are useful for detecting allergies to airborne particles, foods, insect stings, penicillin, and other substances. Here are the most common, least expensive types of allergy tests used for allergy testing in children:
Percutaneous and intradermal skin tests. Skin tests are administered by applying a diluted allergen to a prick or a scratch in the top layer of the skin (the percutaneous method) or by using a 26- to 30-gauge needle to inject the diluted allergen into the skin (the intradermal method). Both are considered extremely safe and relatively accurate. Percutaneous skin testing is rarely conducted on infants younger than 6 months old, but there is otherwise no age limit.
An allergist may opt for intradermal testing, which is more sensitive, if its strongly suspected there is a venom or penicillin allergy that was not detected by a percutaneous test. Intradermal tests, though low risk, can cause anaphylaxis in highly sensitive patients, so its important to be sure the allergist is prepared to treat such reactions.
The accuracy of both tests can be undermined if children are on certain medicationsantihistamines, antidepressants, and high-dose, long-term steroidsso the use of these drugs should be curtailed well before appointment day. Asthma medications or short bursts of oral steroids will not affect the results. According to the National Heart Blood and Lung Institute, selected patients with asthma should undergo skin or blood allergy tests to better understand how allergens are affecting their disease and learn how to avoid specific substances, such as dust mites or pet dander, that worsen symptoms.
After either type of test is administered, the area of the skin is observed for about 15 minutes to see if a reaction flare develops. A wheala raised, red, itchy bumpindicates the presence of the allergy antibody when the child comes in contact with specific allergens. The larger the wheal is, the greater the sensitivity.
Patch tests. Patch testsdelayed-type hypersensitivity skin testscan be used to diagnose allergic contact dermatitis that flares when children are exposed to substances like rubber, fragrances or hair dyes. The only patch test cleared by the Food and Drug and Drug Administration (FDA) is the T.R.U.E. (Thin-layer Rapid Use Epicutaneous) test, which screens for about 25 percent to 30 percent of the most common contact allergens. Patients are asked to leave the patch test in place for 48 hours and keep it dry. An allergist will read the results at certain intervals following the test.
Blood (in vitro) tests. Another way an allergist might perform allergy testing in children is through a blood test, such as a radio allergosorbent test, which is used when skin tests are hard to administer (for instance, if the child is unable to stop taking medication that would obscure the wheal and flare results). This and other similar tests may be less sensitive than skin tests for detecting food allergies, however.
Elimination diet tests. For children with suspected food allergies, the allergist may recommend and supervise a week-long diet that eliminates and isolates foodscommon culprits are milk, soy, eggs, peanut, wheat, tree nuts, or shellfishsuspected of causing a reaction. The downside to this approach is that such diets may be hard for children and parents to follow. They also may produce inaccurate or unclear results because of the many foods allergens disguised in packaged and processed foods. Allergists can also administer food challengesgiving patients certain foods in a controlled environment to assess reactions.
For young children, an allergy test can be a little scary, but helping them understand what to expect can go a long way to reducing their fears.
To schedule an allergy test for your child, locate an allergist near you.