Allergy testing for frequent allergy symptoms
The implementation of an allergy test is the prerequisite for initiating an appropriate therapy. An allergy test is used to find out the cause of persistent or frequently recurring ailments and to identify any existing allergic sensitisations. The implementation of an allergy test is useful if frequent allergic signs and symptoms occur. These include, for example, colds, eye and mucous membrane irritation or, in extreme cases, even an unexpected allergic shock.
A skin prick test is performed if a type I allergy, the so-called "immediate type", is suspected to exist. With these allergies, the corresponding symptoms become noticeable within a few seconds or minutes after exposure to the allergen. A defined allergen extract is dropped onto the skin here and then slightly pierced with a lancet so that the respective substances penetrate into the epidermis. The test reaction can be read after 20 minutes compared to two empty tests always also carried out together (positive control with histamine) and an active substance-free negative control. The skin prick test is usually painless.
Here, a defined amount of an allergen extract (e.g. insect venom) is injected intracutaneously and also read against an empty test after 20 minutes (see above). Since the amount of allergen is greater than with the skin prick test, the reactions can be more severe. If the skin prick test is inconclusive, the IC test is used especially for insect venom allergy sufferers or to clarify some drug allergies.
In some cases, it may be useful to test materials directly. Then the skin is scratched specifically and a suspension of the material is applied to the skin (e.g. collected bed dust). With this scratch test, the allergy test solutions penetrate deeper into the skin through the small scratches than through the mini-needle pricks with the skin prick test. As with the skin prick test, a possible allergic reaction can be seen after 20 minutes.
This test is used to detect a so-called type IV allergisation. A classic example of this is contact allergies, such as a nickel allergy. With the type IV allergy, the allergic reaction is time delayed. Here defined preparations of allergens in carrier substances (such as petroleum jelly or water) are glued onto the skin under test chambers. The test reading is then usually carried out at 24, 48 and 72 hours.
Der RAST-Test (Radio-Allergo-Sorbens-Test) zeigt wie viele spezifische, allergieauslösende Antikörper (IgE) im Blut vorhanden sind. Ein RAST-Test kann bei bestimmten Gegebenheiten bei Allergien vom Soforttyp (Typ-I-Allergien) vorgenommen werden. Der RAST-Test wird oft als weitere Untersuchung nach Allergie-Hauttests (z.B. Prick-Test) vorgenommen um den Schweregrad der Sensibilisierung, Allergie festzulegen.