Intranasal sodium citrate in quantitative and qualitative olfactory dysfunction: results from a prospective, controlled trial of prolonged use in 60 patients

K L Whitcroft, N Gunder, M Cuevas, P Andrews, S Menzel, A Haehner, T Hummel, K L Whitcroft, N Gunder, M Cuevas, P Andrews, S Menzel, A Haehner, T Hummel

Abstract

Objectives: We have previously shown that treatment with intranasal sodium citrate may be beneficial in post-infectious olfactory dysfunction. Sodium citrate reduces free intranasal calcium and is, therefore, thought to prevent calcium-mediated feedback inhibition at the level of the olfactory receptor. We aimed to determine whether treatment with a 2-week course of intranasal sodium citrate improves quantitative olfactory function in patients with post-infectious impairment. We also aimed to determine whether sodium citrate is beneficial in treating qualitative olfactory dysfunction.

Methods: We performed a prospective, controlled study. Patients applied intranasal sodium citrate solution to the right nasal cavity for 2 weeks. The left nasal cavity was untreated and, therefore, acted as an internal control. Monorhinal olfactory function was assessed using the "Sniffin' Sticks" composite 'TDI' score, before and after treatment. The presence of parosmia and phantosmia was also assessed.

Results: Overall, there was a significant increase in TDI after treatment (using the best of right and left sides). Treatment with sodium citrate did not significantly improve quantitative olfactory function, compared to control. The proportion of patients reporting parosmia did not change significantly after treatment. However, there was a significant reduction in the proportion of patients reporting phantosmia, at the end of the study period.

Conclusions: Treatment with intranasal sodium citrate for a period of 2 weeks does not appear to improve quantitative olfactory function in patients with post-infectious impairment, compared to control. It may, however, be beneficial in treating phantosmia, which should be further addressed in future work.

Keywords: Functional anosmia; Hyposmia; Olfaction; Post-infectious olfactory dysfunction; Sodium citrate; Treatment.

Conflict of interest statement

The authors have no conflicts of interest to declare.

Figures

Fig. 1
Fig. 1
Box and whisker plot showing TDI scores before and after treatment with intranasal sodium citrate. Error bars 5–95% interval
Fig. 2
Fig. 2
Box and whisker plots showing change in TDI score (top left), threshold score (top right), discrimination score (bottom left) and identification score (bottom right) before and after treatment with intranasal sodium citrate (right) or no treatment (left). Error bars 5–95% interval
Fig. 3
Fig. 3
Box and whisker plots showing change in TDI score before and after treatment with intranasal sodium citrate (right) or no treatment (left), in patients under 61 years (left) or 61 years and over (right). Error bars 5–95% interval
Fig. 4
Fig. 4
Bar charts showing number of patients experiencing parosmia or phantosmia before and after right-sided treatment with intranasal sodium citrate. The reduction in proportion of patients with phantosmia after treatment was statistically significant (p = 0.001)

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Source: PubMed

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