Tests For Allergy
TESTS FOR ALLERGY:
Allergy tests are used to determine the specific substances that cause an
allergic reaction in an individual.
They may also be used to determine if a group of symptoms is a true
allergic reaction, which involves antibodies and histamine release. Some food intolerances,
in which there is an inability to digest a food because of lack of appropriate
enzymes, produce symptoms similar to allergies. Some drugs, such as aspirin, can
cause allergy-like symptoms without the formation of antibodies or the release of
histamine.
There are many methods of allergy testing. Among the more common are:
- Skin tests
- Elimination-type tests
- Radioallergosorbent test (RAST).
1.SKIN TEST:
Skin tests are the most common. Specific methods vary. The scratch test,
one of the most common methods, involves placing a small amount of suspected
allergy-causing substances on the skin, usually the forearm, upper arm, or the
back. Then, the skin is scratched or pricked so the allergen goes under the skin’s
surface. The health care provider closely watches the skin for signs of a
reaction, usually swelling and redness of the site. Results are usually obtained
within about 20 minutes, and a number of allergens can be tested at the same time.
Penicillin and closely related medications are the only drugs that can be
tested using skin tests. Skin tests for other drugs are at best non-informative
and can be dangerous.
2.ELIMINATION TESTS
An elimination diet can be used to check for food allergies. An elimination
diet is one in which the suspected foods are avoided for several weeks and then
gradually re-introduced one at a time while the person is observed for signs of
an allergic reaction.
3.BLOOD TESTS
RAST measures the amount of specific IgE antibodies in the blood. These
antibodies are present if there is a true allergic reaction.
