Diagnosis of IgE mediated allergy in clinical practise.

The basis of an allergy diagnosis is the patient's case history. In patients with inhalant allergy, an accurate diagnosis is often received when the case history is supported by the result of skin prick test (SPT) or in vitro-test for allergen specific IgE. IgE screening tests should, in cost-effective clinical routines, preferably be used in patients with a doubtful allergy history, in order to find out which patients do not require allergen specific testing. Determination of allergen specific IgE in the serum could be used when there is suspicion of allergy against only one or a few allergens, whereas SPT should be used when testing with many allergens is necessary. In patients with suspicion of allergy against food stuffs or drugs, test methods are of more limited value than in inhalant allergy and double blind placebo controlled challenge tests often have to be performed in order to get a definitive diagnosis. In insect venom allergy, the history should be supplemented with SPT and determination of venom specific IgE before starting desensitisation therapy.