Allergy Testing

What is an Allergy?

One definition of allergy is; a damaging immune response by the body to a substance, such as pollen, fur, a specific food, or dust, to which the body has become hypersensitive. Or in other words; an allergy is an overreaction by the body's immune system to a substance that is harmless to most people. Unfortunately for some people that suffer from an allergy the body's immune system reacts to the substance (known as an allergen) as though it was threatening invader and reacts in such a way that results in symptoms that can range from mildly irritating to being potentially harmful, and even fatal, to the allergic person.

Allergy Testing

Some allergies are relatively easy to recognise and will be diagnosed as the pattern of symptoms following exposure to certain allergens can be detected easily without testing. Other allergies may not be as obvious as the allergic reaction may be suggestive of some other condition. In such cases an allergy test or series of tests may be necessary.

The surface of our skin contains mast cells that retain the body's allergic reaction memory. These mast cells, which are on the surface of eyes, nose & sinuses, mouth and tongue, throughout your breathing and eating tracts, recognise what substances cause us to react. When we have an allergic reaction our mast cells erupt, releasing a number of chemicals that cause difficulties for the sufferer. For example, hay fever sufferers have difficulties when pollen affects the eyes, nose and sinuses.

How Allergy Testing Works

Skin Allergy Testing

With skin allergy tests, the tester applies a small but concentrated amount of the allergen on to the skin on the forearm or sometimes on the back. There are three main types of of skin tests however in each case the mast cells in the skin are exposed to suspected allergens. If the subject has an allergy to the substance being tested the mast cells will erupt and a reaction will be visible. The size and extent of the swelling will inform the tester just how allergic the person is to the individual substances. This form of allergy test is usually performed for allergies for substances such as dust mites, cat hair, horsehair, grass pollen and some specific foods. Skin allergy testing are easily done and is relatively inexpensive.

Skin Prick Allergy Test

With a skin prick test the skin is scratched is pricked to allow the test drop to come into direct contact with the mast cells mentioned above.

Intradermal Allergy Test

With an intradermal test the allergen is injected into the skin. As it is a more sensitive test than a skin prick test it is often used to test for an allergen that has not caused a reaction with the prick test but it is still suspected to be causing an allergic reaction.

Skin Patch Allergy Test

During a skin patch test the allergen is placed on a pad that is attached to the skin for one to three days. A skin patch test is intended to detect a skin allergy called contact dermatitis.

Blood Testing for Allergies

Allergy blood tests are used when skin tests prove inconclusive or for people who may not be able to undergo skin testing. Allergy blood tests, that look for antibodies in the blood, are not as sensitive as skin tests. The most frequent form of blood test for allergies used is the enzyme-linked immunosorbent assay. This test measures the blood level of a certain type of antibody called immunoglobulin E that the body may produce in response to certain allergens. Immunoglobulin E levels are very often higher in people that have allergies or asthma. Other laboratory testing approaches, such as radioallergosorbent testing or an immunoassay capture test, can be used to provide more information about the subjects and their allergies.

Irish Kinesiology Therapists for Allergy Testing