Comparison between odor thresholds for phenyl ethyl alcohol and butanol.

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.