Clinical immunology review series: an approach to the use of the immunology laboratory in the diagnosis of clinical allergy

Abstract

In the last 10 years UK immunology laboratories have seen a dramatic increase in the number and range of allergy tests performed. The reasons for this have been an increase in the incidence of immunoglobulin E (IgE)-mediated allergic disease set against a background of greater public awareness and more referrals for assessment. Laboratory testing forms an integral part of a comprehensive allergy service and physicians treating patients with allergic disease need to have an up-to-date knowledge of the range of tests available, their performance parameters and interpretation as well as the accreditation status of the laboratory to which tests are being sent. The aim of this review is to describe the role of the immunology laboratory in the assessment of patients with IgE-mediated allergic disease and provide an up-to-date summary of the tests currently available, their sensitivity, specificity, interpretation and areas of future development.

Fig. 1

Comparison of the three main methods currently used for the detection of specific immunoglobulin E (IgE).

Fig. 2

Peanut skin prick test wheal diameter in equal-sized populations of affected and unaffected individuals. A majority of unaffected have negative results and a majority of affected have wheals greater than 5 mm. Wheal diameters of 3–4 mm are approximately equal in the affected and unaffected populations and therefore give no information about whether or not the patient is allergic.

Fig. 3

Fagan nomogram for evaluating posterior probability from prior probability and likelihood ratio [12].