Evaluation of qualitative and quantitative taste alterations in COVID-19

Abstract

A large percentage of coronavirus disease 2019 (COVID-19) patients have taste dysfunction. Interleukin 6 (IL-6) levels in mild and moderate COVID-19 patients with the type (quantitative or qualitative) of taste disorders were compared in this observational study. The 208 COVID-19 patients (118 men and 90 women) revealing only taste dysfunctions as prodromic symptoms were classified as mild and moderate patients. Survey results were used to evaluate the taste disorder. The IL-6 levels were measured using a chemiluminescence assay. Statistical analysis was conducted using the Wilcoxon rank, Welch's, and Mann-Whitney tests. The findings revealed that neither the presence of dysgeusia or phantogeusia nor the perception of sour and salty, differed statistically significantly between moderate and mild patients (P > 0.05). But between moderate and mild patients, there were statistically significant differences in how umami, bitter, sweet, and parageusia were perceived (P < 0.05). There was an impairment of multiple tastes up to ageusia in patients with high IL-6 levels. The findings demonstrated that parageusia and dysfunctions in umami, bitter, and sweet taste perception can be indicators of more severe forms of COVID-19.

Figure 1.

Distribution of IL-6 values. (A) In total sample, (B) in mild patients, and (C) in moderate patients. IL-6: Interleukin 6.

Figure 2.

Summary scheme of the probable mechanisms of onset of taste disorders (qualitative and quantitative). GPCR: G-protein-coupled receptors; IL: Interleukin; INF: Interferon; TNF-α: Tumor necrosis factor α; ROS: Reactive oxygen species.