Allergies Library
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Allergy Tests
Results
A skin or blood test can tell you what substance, or allergen, may trigger an allergic response.
Skin tests
Skin tests work by exposing a person to suspected allergens and seeing if a reaction occurs. The results of the skin tests will be available immediately after testing is done.
Normal (negative): | No raised red areas (called wheals) are created by the allergen. |
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Abnormal (positive): | A wheal created by the allergen is at least 1/8 inch (3 mm) larger than the reaction to the negative control. The larger the wheal, the more certain it is that the person is allergic to that specific allergen. |
Blood tests
Allergy blood tests look for substances in the blood called antibodies. Results of allergy blood tests are usually available in about 7 days.
Normal (negative): | The levels of immunoglobulin E (IgE), a type of antibody, are the same as in a person who does not have allergies. |
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Abnormal (positive): | The levels of immunoglobulin E (IgE) antibodies for a particular allergen or group of allergens are 4 times the normal level. |
Last Updated:
June 30, 2011- Medical Review:
- E. Gregory Thompson, MD - Internal Medicine
Rohit K Katial, MD - Allergy and Immunology
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