Allergy Tests


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There are a wide variety of ways to diagnose allergies. They range from simple skin prick testing to blood cell counts. It’s best to visit your GP in the first instance and have a thorough physical exam and discuss your general health history. Once the GP has this information to hand, possible routes of allergy screening can be discussed and a decision can be reached on the best possible way forward towards an accurate diagnosis. Screening can take place in several ways. Listed below are the most common screening methods available.

Skin Prick Test for Allergies

The skin prick test involves making a small needle prick in the skin in which to introduce a tiny amount of the allergen. Should you be allergic to the sample being applied, a reaction will be set off in the body. Mast cells will be prompted to release histamine. This in turn will cause the redness and swelling seen in an allergic reaction. If a reaction does occur, it is localised to the specific allergen that was applied the prick site. Depending on the number of tests you are actually having at a particular time, the duration of the screening can vary.

Intradermal Test for Allergies

This test differs from the skin prick test in that a syringe is used to inject the allergen underneath the skin as opposed to shallowly on the surface layer. It is more sensitive and a good alternative should the above test fail to produce a positive result.

Patch Testing for Allergies

Similar in theory to the prick test and Intradermal test, the difference being the allergen is applied via a small patch.

Scratch Test for Allergies

Not used very much at present due to the wide variety of more accurate methods available. The test involves the abrasion of a small patch of skin in which to apply the allergen and watch for any reactions that occur.

Challenge Testing for Allergies

A more invasive method of allergy screening, this test is actually based on the direct ingestion or inhalation of the particular allergen being tested for. It can be very dangerous and requires constant supervision. One downside to this test is the possibility of anaphylactic shock if not carefully monitored.

RAST Test for Allergies

A RAST (radio allegro sorbent) test involves drawing blood, and is usually used as an alternative in cases in which it is not possible to do the more common skin tests. This might be in cases where certain medications are being taken by the patient, or where the actual skin itself is not suitable for testing.

WBC Differentiation for Allergies

The white blood cell differentiation test can be used to detect the severity of allergic reactions. It is usually ordered as part of a larger test panel called a complete blood count (CBC.) The test will show how many of each type of blood cell is present. Elevated eosinophil levels tend to indicate an allergic response is likely to be occurring

Elimination Diet for Allergies

This type of diet can be used to diagnose allergic responses, and is not only specific to testing for food intolerance.


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