Diagnosis of allergies
The first diagnostic element that a specialist uses to diagnose allergic disease is the medical history which includes symptoms and their potential relationship to allergens, relevant characteristics of the patient’s home, existence or non-existence of a family history, and other information.
Next, using the medical history and the examination as a guide, skin tests are performed. These tests attempt to reproduce an allergic reaction on the skin by means of inoculation with the suspected allergens. A skin prick test, the most commonly used technique, consists of depositing a drop of allergen on the skin and then pricking it.
At times, depending on the allergen and/or signs and symptoms an intradermal reaction test is used. In this technique, a tiny amount of allergen is inserted into the skin using an insulin syringe.
Both tests are performed on the anterior forearm, are read after 15-20 minutes and always include a negative control and a positive control to establish a standard for comparison.
Sometimes, as an additional test, the presence of IgE antibodies in blood is examined and the specific IgE to a particular allergen or to a certain protein thereof is quantified.
When a confirmatory diagnosis is not reached with the above tests, provocation tests are performed. These attempt to reproduce the potential allergic reaction in the affected organ — the nose, conjunctiva or bronchi — by administering the allergen under highly controlled circumstances.
For the most part, allergies are diagnosed through a good medical history and skin and blood tests.