When a patient is being evaluated for allergy, the most important information is the clinical
history of the patient’s symptoms. If the history is suggestive of allergy, confirmation and
identification of the allergens is next. The purpose of allergy testing is to identify a specific
allergen that has resulted in the production of the antibody, IgE. It is the specific IgE antibody
that is responsible for triggering the allergic reaction.
There are two recognized methods for identifying a specific allergy IgE antibody. The most
commonly used by allergists is allergy skin testing. In cases where skin testing in not possible a blood test screening for a panel of allergens can be ordered. Again this blood test is identifying a specific IgE antibody.
Allergy skin testing by allergists consists of prick skin testing and if indicated followed by intradermal skin testing. Both skin tests introduce the suspected allergen to sensitized mast
cells below the surface of the skin. If a specific IgE is on the mast cell, the mast cell will
release histamine and this results in a wheal and flare which is similar to a mosquito bite.
Histamine is the major cause of many allergy symptoms.
As skin testing has been found to be more accurate, immediate with results in 15 minutes and less expensive than the blood test, this is the preferred method of identifying an allergen. In my opinion, allergy skin testing is more relevant as well, as this is a clinical demonstration of a specific allergy to both the allergist and more importantly to the patient than a report from a blood test.