San Diego Allergy, Asthma & Immunology Consultants, Inc
Bernard A. Feigenbaum, M.D. FACP, FAAAAI
We perform food allergy skin testing to: wheat, soy, cow's milk, peanut, tree nuts, fish, shellfish, fruits, vegetables, spices and other foods.
(Results in 15 minutes)
The most common type of food allergy is caused by the interaction of Immunoglobulin-E (IgE antibodies) with peanut, soy, wheat, cow's milk and other food allergens. This interaction results in the release of histamine and other inflammatory chemicals from special immune cells called mast cells, possibly resulting in hives, swelling and/or a systemic allergic reaction called anaphylaxis. These types of reaction typically occur within a few hours of eating the food.
Patients with severe food allergies/anaphylaxis are typically educated regarding allergen avoidance, an "Action Plan" including allergic reaction symptoms to watch out for, and are often prescribed an epinephrine auto-injector.
SKIN TEST INTERPRETATION
Testing involves being “pricked” with several Multitest devices. Each white Multitest device has 8 skin testing prongs. Each prong is dipped in a well and each well contains a different aero-allergen or food allergen. 15 minutes later, the results are written down and interpreted.
Your testing sheet will indicate the size of the wheal and the size of the flare, both of which are used in interpreting the reaction. The wheal is the raised area of skin. The flare is the red area of skin surrounding the wheal. For example, a result of 5/15 for alder tree doesn’t mean 5 out of 25. Both numbers are measurements, so it indicates that there was a 5 mm wheal and a 15 mm flare.
Usually (but not always), the larger the wheal and flare response, the worse the allergy.
There is no standard for grading severity, but here are some rough guidelines:
Mild allergy—3/5 to 5/10
Moderate allergy—5/10 to 8/20
Strong allergy—Larger than 8/20
Also, with airborne allergen testing, 1st round reactions are more significant than 2nd or 3rd round reactions.
One of the testing sites contains histamine, which is used as a positive control. An itchy, red, raised histamine site is normal and shows that your skin is reacting as expected to the testing. (It doesn’t mean an allergy to histamine.)