Blood allergy testing detects a specific antibody directed at a specific allergen such as grass, cat, or peanut, etc. Skin Testing is done more frequently because it is generally less expensive and the results are available more quickly. With blood testing there is no interference from antihistamines (which have to be withdrawn for skin testing) and there are greater availability of allergens for testing. In certain situations as food allergy, both skin tests and blood allergy tests are necessary.
The interpretations of blood allergy tests are complex. Your AAATS Board Certified Allergist will integrate information from skin testing and patient's history (e.g. symptoms, age, other allergic illnesses, etc.) to arrive at an ideal management plan). A positive test does not always mean that a reaction will occur with exposure and a negative test does not always rule out an allergy.
Blood allergy tests may be obtained under certain circumstances: inability of the patient to come off antihistamine, severe skin rash, unclear clinical situation. If you have any further questions about these tests, feel free to contact us.