The ongoing pandemic of coronavirus disease 2019 (COVID-19) pandemic has become a serious threat to healthcare systems, worldwide. There is limited evidence regarding how the infection affects the liver and significance of pre-existing liver disease as a risk factor for developing the infection or getting a severe disease. Different treatments for COVID-19 are currently under evaluation, among few may be correlated to hepatotoxicity. The current review evaluated data on the COVID-19 and liver, in order to offer hepatologists with updated recommendations to manage this pandemic. 

Alteration of liver functions is a common presentation in patients admitted for COVID-19. Elevated alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were seen in 16–53% of patients. Patients with severe COVID-19 reported to have higher rates of liver dysfunction. Similar findings were corroborated by a large study from China that showed AST/ALT were increased in 18.2/19.8% of patients with mild and in 39.4/28.1% with severe disease. 

Another study from New York that recruited 5700 patients, among which 58.4% developed AST values >40U/L and 39% ALT >60U/L. Moreover, 2.1% developed acute hepatic injury, defined as an elevation in AST or ALT of >15 times the upper limit of normal. Among these 2.1% (56) patients, 3 were 18–65 years old (3/1373, 0.2%) and discharged alive, while 53 died. The study concluded that as frequency of liver dysfunction increases, the more severe is the COVID-19.

Researchers showed that cause of liver injury in patients with coronavirus infections might be viral infection of liver cells, since studies in patients with SARS were evident of the presence of the virus in liver tissue. Angiotensin-converting enzyme 2 (ACE2), the entry cell receptor for SARS-CoV2, is expressed in both liver cells and bile duct cells. Since it’s The expression is much higher in bile duct cells, due to which COVID-19 liver injury appears to be more associated to its damage than to liver cells injury.

ALT/AST elevation in COVID-19 may also be due to drug hepatotoxicity, cytokine storm and/or pneumonia-associated hypoxia. It has been observed that in majority of COVID-19 patients, liver dysfunction seems to be mild, transient without clinical significance on the outcome of COVID-19 patients. On the other hand, patients at admission with abnormal liver test of hepatocellular type or mixed type had increased risk of developing to severe disease during hospitalization.

Source: Ridruejo E, Soza A. The liver in times of COVID-19: What hepatologists should know. Ann Hepatol. 2020 Jul-Aug;19(4):353-358.