What is the role of an immunoglobulin E (IgE) count in the workup of allergic rhinitis?

Updated: Jan 02, 2020
  • Author: Quoc A Nguyen, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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The IgE count may be determined.

  • In contrast to total IgE, which has a poor clinical correlation, antigen-specific IgE antibodies are important in the diagnosis of inhalant allergy.

  • Compared with skin testing, in vitro testing is more specific, and it is not affected by skin reactivity or medications. It also has no risk of systemic reaction and is better tolerated, because it is less traumatic. However, in vitro testing is less sensitive than skin testing, especially in regard to molds. Also, the results are not available immediately and must be verified with skin testing before immunotherapy can be started.

  • The original method for obtaining an IgE count, the radioallergosorbent test (RAST), has evolved from a radioimmunoassay to a test that involves enzymatic or fluorometric processes (eg, enzyme-linked immunosorbent assay [ELISA]).

    • Fadal and Nalebuff have modified the test to increase its sensitivity and to improve the correlation of its findings to those obtained with the skin endpoint titration method.

    • Scores do not necessarily correlate with the severity of the clinical symptoms. Although they can be used to establish the starting dose for immunotherapy, a vial test still is required before immunotherapy can be initiated.

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