Guide to Allergy Testing

Allergy: What is it?

Allergic disorders result from an inappropriate, usually IgE-mediated, immune response upon exposure to either environmental or food allergens. Common manifestations of allergy include rhinoconjunctivitis, asthma, eczema, acute urticaria and anaphylaxis.

Disorders, such as chronic urticaria, hereditary angioedema and T-cell contact dermatitis (metal allergy), while clinically similar in some ways, are not IgE-mediated. Allergic disease manifests in different ways through life and the likely causative agents can also change with age (see Table 1).

Tests used in the diagnosis of IgE-mediated allergy

Total IgE

Higher levels of total IgE are often found in patients with allergic conditions. However, normal total IgE does not exclude allergy.

Total IgE is also elevated in other conditions including parasitic infections and allergic bronchopulmonary aspergillosis. It is used increasingly in determining anti-IgE therapy in moderate to severe ...

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