Hyposmia in allergic rhinitis.

BACKGROUND: The association between nasal allergy and loss or diminution of smell is frequently alluded to in the literature; however, neither the true prevalence of hyposmia in individuals with allergic rhinitis nor its bases have been established.
METHODS: We assessed olfactory threshold for phenylethyl alcohol in 91 patients with symptoms of allergic rhinitis and 80 nonatopic control subjects. To determine the degree to which nasal congestion contributes to hyposmia in allergic rhinitis, total nasal resistance was measured in 64 of the patients and 72 of the control subjects.
RESULTS: Olfactory thresholds were significantly higher in allergic patients than in control subjects (p < 0.001), with 23.1% of the patients demonstrating a clinically significant smell loss (defined as threshold at or above the 2.5th percentile of control values). Although nasal resistance was significantly higher among patients than among controls (p < 0.001), it was not related to olfactory threshold in either group. Clinical or radiographic evidence of sinusitis or nasal polyps or both in allergy patients was found to be significantly associated with hyposmia (p < 0.006).
CONCLUSIONS: The observed prevalence of hyposmia among patients with allergic rhinitis suggests that this is a major etiologic factor contributing to smell disorders. Sinusitis or nasal polyps or both may underlie many cases of allergy-related hyposmia.