If your family doctor
thinks you might have an allergy, he or she
will probably refer you to an allergist (a
doctor who specializes in diagnosing and treating
allergies) for further testing. Here's what
to expect.
An allergist will
ask questions, such as:
What symptoms do
you notice when you have a reaction? (e.g.,
hives or a scratchy throat)
How often does
the reaction happen?
How long does it
take between eating a particular food and
the start of the symptoms?
Do any family members
have allergies or conditions like eczema
and asthma?
The allergist will
probably also do tests. Skin tests are the
most common type of testing used to diagnose
allergies.
Skin
Tests
A skin prick or scratch
test involves placing liquid extracts of allergens
(such as pollen or food) on a person's forearm
or back, then pricking the skin a tiny bit.
The allergist then waits 15 minutes or so
to see if reddish, raised spots (called wheals)
form, indicating an allergy.
A few doctors may
do a similar test, called an intradermal test,
under the surface of the skin. This type of
test is usually done to look for .
If the doctor thinks
a person might be allergic to more than one
thing — or if it's not clear what's triggering
a person's allergy — the allergist will probably
skin test for several different allergens
at the same time.
Skin tests may itch
for a while. The allergist might give
you antihistamine or steroid cream after the
test to lessen the itching.
Testing
for Food Allergies
Doctors use skin tests
to diagnose environmental allergies. But it's
different with food allergies. When a skin
test shows up as positive with a certain food,
that only means a person might be
allergic to that food. In these cases, doctors
may want to do additional testing.
To diagnose a food
allergy for certain, an allergist may do a
blood test in addition to skin testing. This
involves taking a small sample of a person's
blood and sending it to a laboratory for analysis.
The lab checks the blood for IgE antibodies
to specific foods. If there are enough IgE
antibodies to a particular food in the blood,
it means it's very likely that person has
an allergy.
Doctors often use
a combination of skin testing and blood testing
to diagnose a food allergy. If both come up
positive, there's no need for further testing.
If the results of
the skin and blood tests are still unclear,
though, an allergist might do something called
a food challenge. During this test, the person
is given gradually increasing amounts of the
potential food allergen to eat while the doctor
watches for symptoms.
Because food allergies
can trigger serious reactions in people, this
test can be risky. So it needs to be done
in an allergist's office or hospital that
has access to medications and specialists
to control reactions like . Doctors only occasionally
use the food challenge to diagnose a person
with a food allergy. Most of the time, this
type of test is done to find out if someone
has outgrown a known allergy.
Test
Results and Treatment
If an allergist decides
that a person has an allergy, he or she will
recommend a course of action. Treatment depends
on the allergy — for people with environmental
allergies, this might mean the allergist prescribes
medication or allergy shots. For a food or
other allergy, the allergist will advise the
patient on ways to avoid the allergen.
