UNLABELLED: Aim of the study was to compare results of odor threshold test using different numbers of dilution steps, separately for butanol and phenyl ethyl alcohol (PEA).

METHODS: A total of 116 subjects participated (29 patients with olfactory dysfunction and 87 normosmic subjects). The olfactory threshold for butanol and PEA was examined with 8 (wide step method) and 16 (narrow step method) dilutions. With a delay of about 1 week, all 4 tests were repeated.

RESULTS: Test time was shortened by approximately 2 min (25%) for patients when using the wide step method. Butanol and PEA thresholds were not significantly different; in addition, a significant correlation was found between thresholds for the 2 odors (r = 0.60, P < 0.001). Threshold test with both odorants as well as with wide or narrow step method provided satisfying reproducibility (test-retest reliability: r = 0.80-0.84, P < 0.001). Patients with olfactory dysfunction could be clearly separated from normosmic subjects using all 4 different tests.

DISCUSSION: The results indicate that threshold testing with PEA is an alternative to butanol. The wide step method provided similar results as the narrow step method but required less time.