The use of in vitro diagnostic tests and assays in the diagnosis of allergy and the identification of the causative allergens is endorsed by the Allergy Society of South Africa. All these tests described here are used and recommended by individual opinion leaders, experts and specialists in the field of allergy in South Africa. The initial step in the diagnosis of allergy is the differentiation of allergy from other conditions that may mimic the symptoms of allergy. It is therefore important to reliably establish that a patients symptoms are indeed due to an allergy. A thorough clinical history remains the cornerstone of a confident and reliable allergy diagnosis.
Diagnostic tests are to be used as an adjunct to the history.
After the development of the assay for the measurement of Total IgE, it has been widely used as an indicator of allergy. There are however several clinical limitations and disadvantages to the measurement of Total IgE, that severely restricts its application and value, especially in the South African medical environment. The normal range, or reference range of Total IgE is dependent on and therefore varies with the age of the patient. The internationally accepted reference range that has been established over the years is applicable only to the Caucasian population. The high incidence of parasites in certain sections of the South African population, particularly Ascaris, limits the application of the Total IgE assay as a test for allergy.