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: Allergy testing can be very useful in children
DEAR DR.PAUL: Our six year-old-son is to be tested for
allergies to several foods and pollens. I have two questions:
What are allergy tests exactly? And at what age can these tests
be performed? Thank you.
DR.PAUL ANSWERS: Up to 10-15% of all children may have
allergic tendencies. Allergy-prone children can either develop
asthma, nasal allergies, eczema and/or food allergies. An allergy
develops when a person's body has a bad reaction to a particular
substance or product that's normally harmless, such as cow's
milk protein or pollens.
The substance that causes the allergic reaction is called an
allergen. Allergens can enter the body when they're eaten, touched,
inhaled or breathed in. When the body perceives the allergen
as something harmful, it tries to protect itself by by making
antibodies which attack the allergen. In the process, the person
experiences various allergic symptoms that can range from mild
to severe.
Allergy testing helps us determine exactly what a person is
allergic to by detecting whether a person has developed an antibody
against a tested substance such as a specific food, airborne
allergen or a medication. The easiest and most common way to
do this is the "Scratch Test", a simple and relatively painless
procedure. A series of drops, each containing a specific antigen,
is placed on a child's forearm. Next, with a small needle, the
area of skin at each drop is pricked very gently. After a 10-minute
waiting period, if there is an allergy to a specific substance,
a small bump will develop at the site of the scratch. The size
of the bump, and the size of the surrounding redness, indicate
how much a child is allergic to the specific substance tested.
In general, the test is very safe and does not induce an allergic
reaction in the child, other than a local one at the site of
the scratch. However, we generally do not perform the test if
an asthmatic child has active symptoms at the time of the testing.
Allergy tests can be performed at any age. But when testing
for respiratory allergens, I believe the tests are more reliable
in children five years of age and older. For foods, such as
milk protein or peanuts, we test at any age. Allergy tests can
help us identify what specifically is causing an allergic reaction
or worsening a child's asthma.
In the case of a food allergy, the test can determine whether
a specific food has to be avoided in the diet. In the area of
pollen allergies, the situation is more complex. There are different
pollens which appear during different times of the year. Knowing
which pollen a child is specifically allergic to, can help better
prepare the child during a specific pollen season. Parents often
wonder if allergy tests are helpful in determining the cause
of eczema in their children. Disappointingly, the answer is
usually no.
On a final note, one substance we do not test for is cigarette
smoke ... as everyone is sensitive to the effects of second
hand smoke.
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replace the advice and care of your child's physician, nor is
it intended to be used for medical diagnosis or treatment. If
you suspect that your child has a medical condition, always
consult a physician.
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