Liver injury in patients with COVID-19 in comparison to patients with the pandemic influenza A (H1N1) 2009: a population-based study

Elevated liver tests in patients with COVID-19 are widely reported. Population-based studies utilizing a validated analysis of drug-induced liver injury (DILI), with a control group of other viral illnesses and follow-up are largely lacking.

All hospitalized patients in Iceland with SARS-CoV-2 in 2020 and pandemic influenza A (H1N1) in 2009 were included in this retrospective, population-based study. Liver tests were compared between the two groups and the correlation to inflammatory markers and persistence of alanine aminotransferase (ALT) elevations were assessed. Potential DILI cases were reviewed using the Roussel Uclaf Causality Assessment Method (RUCAM).

225 SARS-CoV-2-positive and 73 influenza A (H1N1)-positive patients were included. Liver test values were similar between the groups, except for aspartate aminotransferase (AST) which was significantly lower in COVID-19, with a mean difference of 26 U/L (95%CI 4.2-47). Ferritin elevation was positively correlated with ALT, AST and alkaline phosphatase. No patient had persistently elevated ALT in COVID-19 and none had a probable DILI. Only 3 patients had a possible DILI according to the RUCAM.

Elevated liver enzymes are not specific for COVID-19. Hyperferritinemia was associated with elevated liver tests. DILI was very rare in COVID-19 and an unlikely cause of elevated liver enzymes in COVID-19. Abnormal liver tests are nonpersistent and generally not clinically important in these patients.