Sources and clinical significance of aspartate aminotransferase increases in COVID-19

BACKGROUND: Aspartate aminotransferase (AST) is often increased in COVID-19 and, in some studies, AST abnormalities were associated with mortality risk. METHODS: 2054 hospitalized COVID-19 patients were studied. To identify sources of AST release, correlations between AST peak values and other biomarkers of tissue damage, i.e., alanine aminotransferase (ALT) for hepatocellular damage, creatine kinase (CK) for muscle damage, lactate dehydrogenase for multiorgan involvement, alkaline phosphatase and γ-glutamyltransferase for cholestatic injury, and C-reactive protein (CRP) for systemic inflammation, were performed and coefficients of determination estimated. The role of AST to predict death and intensive care unit admission during hospitalization was also evaluated. All measurements were performed using standardized assays. RESULTS: AST was increased in 69% of patients. Increases could be fully explained by summing the effects of hepatocellular injury [AST dependence from ALT, 66.8% [95% confidence interval (CI): 64.5–69.1)] and muscle damage [AST dependence from CK, 42.6% (CI: 39.3–45.8)]. We were unable to demonstrate an independent association of AST increases with worse outcomes. CONCLUSION: The mechanisms for abnormal AST in COVID-19 are likely multifactorial and a status related to tissue suffering could play a significant role. The clinical significance of AST elevations remains unclear.