Skin tests are
main tool in diagnosing allergies all over the world. It is out
patient procedure and patient can go to school or office after
the test. Each and every patient has different allergy profile
which can be known by the skin allergy tests.
allergen triggers can assist in formulating an avoidance
strategy. A trial of allergen avoidance may be diagnostic and
Mechanism of skin
antibodies which are responsible for allergies are present under
the skin as well as other parts of the body. If an allergen to
which patient is allergic is applied to the skin a reaction
occur and a wheal is formed. The size of the wheal is measured
to grade the severity of allergy.
There are number
of ways to perform skin tests:
Patch test (
used mainly for diagnosing contact dermatitis)
Skin prick test
Skin end point
kustner test ( Passive transfer test)
RAST (Radio allegrosorbent technique):
This test detects
allergen specific IgE in the serum of the patients. The results
of the tests correlate well with the skin allergy tests. One
sample of the serum can be used to test many allergens. This
test has many benefits over the conventional skin allergy tests.
It can be used where the skin allergy tests cannot be performed
like young children, severe atopic dermatitis, dermatographism,
history of extreme sensitivity, patients afraid of multiple
The result of RAST
is not influenced by drugs while skin tests are suppressed by
anti allergic drugs and steroids.
There is no risk of anaphylaxis with RAST.
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CBC is done to
rule out tropical pulmonary eosinophilia and other infections.
Chest X-ray is
done if there is suspicion of presence of some other disease
like infection, large airway lesions, obstruction by foreign
object or heart disease. It is also done if a patient is not
improving after taking asthma medication.
This test is used
if congestive heart failure is suggested based on history and
physical examination findings.
Gastroesophageal reflux assessment:
A barium swallow
and 24-hour pH probe is done to diagnose gastroesophageal reflux
disease (GERD), especially if a patient is not responding to
If a patient has
prominent symptoms of GERD, medical therapy is often tried
without performing these tests.
is also done if they are suspected of contributing to the asthma
1. Direct and
indirect laryngoscope is indicated if any laryngeal abnormality
exercise testing is indicated if the cause of dyspnea
(breathlessness) cannot be determined.
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