Allergy tests
Overview of allergy tests for typical symptoms
An allergy test should be carried out if allergic complaints and symptoms occur frequently. These include, for example, skin rash, itchy eyes, runny nose, difficult breathing, diarrhea and irritation of the mucous membranes.
ALLERGOLOGICAL TESTS
Prick test
The prick test is used if an immediate type allergy (type I allergy) is suspected. With this type of allergy, the symptoms appear seconds or minutes after contact with the allergen. As part of the test, a defined allergen extract is applied to the skin and then lightly pricked with a needle so that the respective substances can penetrate the epidermis. The test is always carried out with a histamine positive control and an active substance-free negative control with physiological saline solution. The reading is taken 20 minutes after application of the substances.
Intradermal test
Here, a defined amount of the allergen extract is injected into the skin and also read 20 minutes after the blind test (see above). Due to the larger number of allergens in the skin test, the reactions can be more intense. The intradermal test is used if the prick test is not conclusive, particularly in the case of suspected allergies to house dust mites and insect venoms or to clarify certain drug allergies.
Scratch test
In some cases, it is advisable to test the material directly. In these cases, a scratch test is recommended. The skin is scratched and the potential allergen is applied. The scratch test is mainly used to rule out drug allergies. The test solutions penetrate deeper into the skin using the scratch technique than through the fine needle pricks of the prick test. The result can be read after 20 minutes.
Epicutaneous test
The epicutaneous test is used to detect a contact allergy (type IV allergy). Typical type IV allergies are fragrance, latex or nickel allergies. When testing contact allergies, the provoked allergic reaction occurs with a delay. The test substances are usually applied to the back. Readings are taken after 24, 48 and 72 hours.
Blood test (RAST)
The RAST test (radio-allergosorbent test) is an antibody test of the blood. The relevant allergy-specific antibodies are the IgE antibodies. RAST tests are carried out for allergies of the immediate type (type I allergies). The test is usually carried out as a follow-up test after allergy skin tests (e.g. prick test) to determine the severity of the allergy.
