COVID-19 and Liver Disease: Answering the Key Questions

For those of us treating patients with liver disease throughout the pandemic, we have anticipated evidence-based guidance regarding the contribution of specific liver disease phenotypes and immune suppression/transplantation on COVID-19 susceptibility and outcome. Now, data are emerging to help answer some of the major questions surrounding COVID-19 and the liver.

Does the Virus Itself Cause Liver Disease?

The answer to this question is still a bit unclear. Multiple early reports^{[1,2,3,4,5,6,7,8,9,10,11]} stated that hospitalized patients with SARS-CoV-2 infection frequently had elevated values on liver biochemistry tests. For example, the reported incidence of elevated serum aspartate aminotransferase (AST) or alanine aminotransferase (ALT) levels ranged from 14% to 83%, yet the magnitude of enzyme elevation was generally reported to be mild and normalized as COVID-19 symptoms improved.

Unsurprisingly, patients with severe liver injury (defined as AST and ALT levels more than five times the upper limit of normal) were more likely to have a complicated clinical course, including having elevated inflammatory markers and requiring intensive care unit (ICU) admission, renal replacement therapy, and/or intubation. Currier and colleagues reported that patients with COVID-19 who had elevated AST and ALT levels had significantly higher odds of these same adverse outcomes and death.

This reflects the multifactorial pathogenesis of enzyme elevation, including a direct injurious effect of the virus on hepatocytes, cytokine or immune-mediated liver damage, drug hepatoxicity, or hypoxia and systemic inflammation.