Evaluation of qualitative and quantitative taste alterations in COVID-19

Taste dysfunctions occur in a large proportion of COVID-19 patients. This observational study compared interleukin-6 (IL-6) levels in mild and moderate COVID-19 patients with the type (quantitative or qualitative) of taste disorders. The 208 COVID-19 patients (118 men and 90 women) showing only taste dysfunctions as prodromic symptoms were classified as mild and moderate patients. The evaluation of the taste disorder was carried out using a survey. The IL-6 levels were measured with a chemiluminescence assay. Statistical analysis was performed using the Wilcoxon rank, Welch's, and Mann-Whitney tests (p <0.05). The results showed that there were no statistically significant differences in the perception of sour and salty, nor in the presence of dysgeusia and phantogeusia in moderate versus mild patients (p>0.05). However, there were statistically significant differences in the perception of umami, bitter, sweet, and the presence of parageusia in moderate versus mild patients (p<0.05). There was an impairment of multiple tastes up to ageusia in patients with high IL-6 levels. The results showed that dysfunctions in the perception of sweet, bitter, umami, and the presence of parageusia can be considered as signs of more severe forms of COVID-19.