Allergy Testing

Excerpt

Over 50 million Americans are affected by allergic rhinitis, and approximately 20 to 30 million are affected by asthma, which commonly has an allergic component. Allergies are becoming more common in urbanized communities. As such, more primary care providers are providing or recommending allergy testing. The most common testing being done by primary care physicians are serum IgE, as they are relatively easy to interpret and can be compared. The mechanism by which allergy testing is as follows; mast cells are activated by IgE antibodies in response to an allergen. The mast cells then release two types of cytokines. The first is rapidly degranulated and cause an allergic reaction. The second type causes a delayed inflammatory allergic response. Consequently, we can use the serum IgE testing to find which specific allergen-induced IgE antibodies have been formed to previous exposures, and use these results to try to predict allergic reactions.

As clinicians use more antibiotics, there has been an increase in reported antibiotic allergies. However, fewer than 10% of patients who believe they are allergic to penicillin actually have a true allergy. To be certain, some clinicians are sending patients for allergy testing. An allergist will either do skin testing, and some are doing oral challenges. Oral challenges and skin testing are becoming more common with food allergies, as there has also been a large increase in food allergies. There are four different types of allergy testing. IgE serum levels are easily obtained in the primary care setting. This test measures the amount of circulating IgE. Further testing is usually done by specialists and includes the classic skin prick test, intradermal testing, and patch testing. Skin prick and intradermal testing measure the reaction of mast cell degranulation in response to an introduced allergen. Skin prick test measures the response of T4 cells hyper-reactivity.