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

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

doi:10.1007/s00405-020-06567-7

K L Whitcroft, M Cuevas + Show 5 more

Open Access

https://doi.org/10.1007/s00405-020-06567-7

Copy DOI

Abstract

ObjectivesWe 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.MethodsWe 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.ResultsOverall, 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.ConclusionsTreatment 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.

Highlights

Olfactory dysfunction affects approximately 20% of the adult population [1, 2], and can cause significant impact on quality of life [3, 4]
Our reason for using the contralateral nostril as control was threefold: 1—use of an ‘internal’ control in this way reduces systematic differences between treated and non-treated groups and thereby reduces the risk of such differences confounding our results; 2—use of an internal control in this way increased the efficiency of our study design; 3—we demonstrated temporary improvement in quantitative olfactory function following a single, monorhinal application of sodium citrate in our previous work; elected to keep this study design [21, 22]
In 2005, Panagiotopoulos and colleagues demonstrated statistically significant improvement in odour identification scores following one-off application of sodium citrate in their cohort of 31 patients with olfactory dysfunction of mixed cause [15]