Intranasal pH and Olfactory Function Among Healthy Adults

To determine whether the site of measurement (over respiratory mucosa (RM) or within the olfactory cleft [OC]), olfactory testing, or repeated pH testing affects pH measurements and whether OC pH affects olfactory function.

This cross-sectional study included 62 healthy adults (38 women, median age: 24 years). They underwent the following measurements: intranasal pH (Restech Dx-pH; Respiratory Technology Corp., Houston, USA) and olfaction ("Sniffin' Sticks" Odor Identification Test [OdorId]; Burghart, Holm, DE). Participants were divided based on the following: sites of testing (RM [n = 27] vs. OC [n = 35]); order of testing (olfactory testing [OdorId] between two pH tests [pH-OdorId-pH, n = 17] versus two pH tests separated by a 20-min interval followed by olfactory testing [pH-pH-OdorId; n = 18]). Comparisons between the first and second pH tests were also performed.

OC pH measurements were significantly lower than RM pH. Repeated pH testing resulted in subsequently more alkaline measurements, while olfactory testing had no effect. Odor identification scores correlated with OC pH but not with RM pH. In an exploratory linear regression model, OC pH predicted 18% of the variance in OdorId scores and was a significant negative predictor of OdorId performance (as pH increases, OdorId decreases).

The OC pH is more acidic compared to that over the RM. Increased acidity in the OC was related to better olfactory function, warranting further investigation in olfactory dysfunction.

NA.