| Allergy testing is n important investigation in establishing the cause of any allergic skin disease, such as eczema, urticaria, contact dermatitis, drug reaction etc. There are two types of allergy testing in
skin.
1.Patch testing is done various cases of contact dermatitis. In this, patches containing various allergens are applied to the back and covered with a plaster. The plaster is removed after 3 days and site is read for any reaction. Any positive reaction ( red rash at the site of application ) is then correlated with history , occupation of the patient and the disease to establish fully the cause of the condition. This is particularly in cases of contact allergens.
2.Prick testing is done in cases of urticaria (wheels) and atopic eczema. Here allergens are introduded in to the skin by a number or pricks or scratches with a needle and the reading done after 30 minutes for developement of any reaction (red wheel). The positive reaction (red rash at the site of application ) is then correlated with history, occupation of the patient and the disease to establish fully the cause of the condition. This is particularly relevant in cases of food allergens and inhaled allergens.
Other methods of testing includes RAST in which blood is drawn and tested for various food, inhaled and contact allergens.
|
