[Allergologic diagnosis]

Abstract

There are two phases in allergologic diagnosis of respiratory diseases related to immediate hypersensitivity reactions: establishment of the allergic origin of the symptoms and identification of the causal allergen or allergens. In addition to the basic information obtained from history taking and physical examination, prick tests provide an easy, rapid, and low cost means of correctly identifying specific allergens. Laboratory tests such as serum assay of specific IgE can be useful when history and prick tests provide conflicting information, in exceptional cases when prick tests cannot be performed, or when specific desensitization is indicated. IgE assay is however of little use if prick tests are negative or clinical history poorly suggestive. The role of screening for atopy using multiple-allergen prick tests which give a global positive or negative result is poorly defined. Screening tests would be interesting if symptoms suggest, among other hypotheses, an allergic disease, especially if prick tests cannot be performed rapidly. Other atopy tests, such as total serum IgE, have little use. Finally, specific provocation tests are rarely needed for routine allergologic diagnosis. They may be useful in complex clinical situations or in particular conditions such as occupational allergy.