Abstract: Objective　To observe the changes of serum cystatin C (CysC) and inflammatory factors in patients with coronavirus disease 2019 (COVID-19), and to explore their relationship. Methods　One hundred and fifty-two adult patients with COVID-19 admitted to the Third People’s Hospital of Hubei Province Affiliated to Jianghan University from January to April 2020 were selected in this study. Patients were divided into common group (n = 110) and severe group (n = 42) according to the clinical classification criteria in the "New Coronavirus Pneumonia Diagnosis and Treatment Program Seventh Edition". The serum levels of CysC, creatinine (Scr), urea nitrogen (BUN), and C-reactive protein (CRP) were detected by an automatic biochemical analyzer. Serum levels of interleukin 6 (IL-6) and amyloid A (SAA) were detected by enzyme-linked immunosorbent assay (ELISA). The correlation between serum levels of CysC, Scr, BUN, IL-6, CRP and SAA were compared between the two groups by Pearson correlation analysis. Results The serum level of CysC and the proportion of patients with increased CysC levels were both significantly higher in severe group than those of common group (P＜0.05). There were no significant differences in the serum levels of  Scr and BUN and the proportions of patients with increased levels between the two groups. The serum levels of CRP, IL-6 and SAA were significantly higher in the severe group than those in the common group (P＜0.05). In the severe group, the serum levels of CysC, Scr and BUN were positively correlated with IL-6 (r=0.647, 0.376 and 0.364, respectively), CRP (r=0.579, 0.374 and 0.351, respectively) and SAA (r=0.524, 0.338 and 0.305, respectively, all P＜0.05). In the common group the serum levels of  CysC, Scr and BUN were positively correlated with IL-6(r=0.615, 0.384 and 0.357, respectively), CRP (r=0.517, 0.345 and 0.323, respectively) and SAA (r=0.491, 0.314 and 0.328, respectively, all P＜0.05). Conclusion　The serum levels of cystatin C and inflammatory factors are higher in COVID-19 severe patients than those in common patients. The elevated levels of inflammatory factors may be one of the mechanisms of kidney injury in COVID-19 patients. 

Key words: coronavirus, pneumonia, viral, coronavirus disease 2019, cystatin C, inflammatory factors