Correlation between vitamin D and anosmia in post acute Covid syndrome clinic

ABSTRACT

Introduction: Anosmia has emerged as a clinical feature of Covid-19. It is estimated over half of patients with Covid19 report anosmia. It is primarily transient, but can persist over a month in around 20% of cases. There is a hypothetical interaction between hypovitaminosis D and diminished smell. A deficiency may lead to neurologic decline in cranial nerves, including the olfactory nerve. Few studies investigating this are available. Loss of smell is a common occurrence through adulthood, with many physiologic and anatomic contributing factors. Limited data is available addressing anosmia post Covid-19. Aim(s) To assess the correlation between vitamin D (VD) and anosmia, in patients referred to post acute COVID syndrome (PACS) clinic, and to assess the variation of data across age groups. Method(s) A "Sniffin' Sticks" test was undertaken for all patients referred to the PACS clinic. This was correlated with a recent serum VD level. Result(s) 143 patients presented to the PACS clinic over a 10 month period. 84% were under 65 years. 60% of these patients who developed anosmia were found to have VD insufficiency. A similar proportion of patients with hyposmia, and patients with normal smell were found to be VD insufficient (36% vs 34.7%). Within the older cohort, none of the patients with anosmia were deficient in VD, and 7.7% of patients with smell dysfunction had insufficiency. Conclusion(s) There is an association between anosmia and VD deficiency in patients under 65 years of age seen at PACS clinic. This did not reflect in the cohort with hyposmia. In the older age group, the majority of patients had normal VD levels, which may indicate other contributing factors towards the decrease in smell.