Prognostic Value of Serial Measurement of Serum Des-Arg(6)-Bradykinin Levels in Severe COVID-19 Patients

Background: Excessive inflammatory immune response during SARS-CoV-2 infection contributes to severe dis-ease in COVID-19 patients. Recently, some researchers hypothesized that dysregulation of the bradykinin (BK) system may also play a role in the pathogenesis of severe disease. Des-Arg(9)-bradykinin (DABK), an active me-tabolite of BK, is responsible for vasodilatation and increased permeability in the lungs and regulated by angio-tensin converting enzyme 2 (ACE-2). Viral inhibition of ACE-2 by SARS-CoV-2 increases DABK levels. Serum levels of this metabolite may be linked to disease severity in COVID-19 patients. In this study, it is aimed to inves-tigate the prognostic value of serial measurement of serum DABK levels in severe COVID-19 patients. Methods: This prospective cohort study was conducted in hospitalized severe COVID-19 patients. Serum DABK levels of patients were serially measured on day 0, day 3 and day 5. Patients were categorized as cases with poor or good prognosis and critical or non-critical cases. Serum DABK levels of these patient groups were compared with paired sample t-test. Serum DABK levels on different days in the same patients were compared with repeated measures ANOVA tests. Results: There was no statistically significant difference in serum DABK levels measured at day 0, day 3, and day 5 between good and poor prognosis groups. DABK levels in critical and non-critical COVID-19 patients also did not show any significant difference. Conclusions: According to our results serially measured serum DABK levels did not correlate with outcome of se-vere COVID-19 and do not have prognostic value in severe COVID-19 patients. (Clin. Lab. 2022;68:xx-xx. DOI: 10.7754/Clin.Lab.2021.211110)