Some laboratories offer a blood test that measures immunoglobulin G (IgG) antibodies to allergenic sub-stances. IgG has never been demonstrated to be an important cause of allergic reactions; in fact, IgG may play a protective role in modulating the severity of allergic responses. IgG antibody tests have not been shown to accurately predict the occurrence of allergic reactions and have not proven useful in differentiating allergic from nonallergic individuals. For this reason, IgG antibody testing should not be used as a diagnostic laboratory test; nor should the results of these tests be relied upon to make recommendations for treatment.
End-point titration intradermal skin testing is an alter-native method of skin testing that involves the injection of incrementally increasing concentrations of allergenic extracts. When these tests are positive at very low concentrations of allergen, the results are comparable to testing done by the prick/puncture method. However, when the tests are only positive at much higher concentrations of allergen, the results more likely represent false positives and do not accurately reflect true allergic sensitivity. For this reason, the prick/puncture method is the preferred testing modality.