Diagnostic Methods for Contact Allergy to Metals

Abstract

The epicutaneous patch testing is regarded as the best method of diagnosis for allergic contact dermatitis (ACD). Patch tests can be used to confirm a suspected allergic contact dermatitis and either to recommend avoidance of particular products or to recommend alternative products in a particular patient. It is based upon re-exposing the skin of the patient to suspected allergens under controlled conditions. Different test sites and test tapes can be used and different variables such as intrinsic penetration capacity, concentration, exposure time and vehicle can be changed to obtain an op- timal bioavailability of the haptens. The ideal patch test should cause as few adverse reactions as possible, and be repro- ducible and specific. In this paper, the application fields, the advantages and the disadvantages of the patch tests are re- viewed. Other diagnostic methods as the open test, the provocative test, the repeated open application test and the photo- patch test are also discussed. the risk of degradation due to humidity, air or light. Most preparations should be kept in a refrigerator and in the dark; those in diluted liquid preferably in dark bottles. The aller- gens should not be stored vertically, to prevent sedimenta- tion and concentration changes of the allergens. The test preparation in petrolatum, kept in syringes, is applied di- rectly onto the test chamber. Liquid test preparations are ap- plied via a digital pipette to allow exact dosing.