Value of food antigen specific IgE-RAST and immediate reaction skin test

Puncture skin tests with crude food extracts correlate well with proved IgE-mediated food allergy. The RAST may be effective in the diagnosis of IgE-mediated food hypersensitivity when purified allergens are used and when crude food extracts are used. A positive RAST to a food may demonstrate IgE antibody directed to that food but not necessarily implies clinical sensitivity. The RAST may not be efficacious for diagnosing in food allergy if the total IgE value is greatly elevated.