Utility of laboratory testing in autoimmune inner ear disease

Objectives: To assess the utility of various laboratory tests used to diagnose autoimmune inner ear disease. Study Design: Retrospective study of 82 patients evaluated at the University of Washington Otology Clinic from 1996 through 1998 with review of clinical history, laboratory tests, audiograms, response to therapy, and final diagnoses. Methods: Charts were reviewed for presenting history and initial workup including test results for erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), C1q binding assay, anticardiolipin antibody (aCL), antineutrophil cytoplasmic antibody (ANCA), microhemagglutinin assay for Treponema pallidum (microhemagglutination assay), Lyme disease titers, and the Western blot for heat shock protein 70 (hsp 70). Results: The Western blot for hsp 70 is the best test for predicting corticosteroid responsiveness. The sensitivity was low at 42%, although the specificity was 90%, and the positive predictive value of this test was excellent at 91%. The ESR was as good as the CRP in detecting acute-phase reactants. The other, more specific tests in the laboratory panel (aCL, ANCA, MHA, and Lyme disease titers) did not detect any new cases of autoimmune disease in addition to those which were already identified by an abnormal ESR. Conclusions: A diagnostic test panel for autoimmune inner ear disease should include an ESR and the Western blot for hsp70. More specific laboratory testing for systemic disease is warranted when the ESR is elevated. In patients with a positive Western blot, a trial of corticosteroid therapy can be given with good conviction because the test is quite specific. However, many people who are Western blot negative may also respond to corticosteroid therapy because the test lacks sensitivity.