In December 2019, a novel coronavirus was identified as the pathogen to cause pneumonia in Wuhan, China , which was temporarily named as 2019-nCoV by WHO. On 11 February 2020, based on the phylogeny, taxonomy and established practice, 2019-nCoV was officially named as SARS-CoV-2, and the disease caused by SARS-CoV-2 was named as COVID-19. SARS-CoV-2 can be transmitted from person to person through respiratory droplets and close contact , posing a huge public health challenge. So far, there were more than a million confirmed cases in 181 countries and regions around the world.

The main manifestations of SARS-CoV-2 infection include fever, dry cough, weakness, and breathing difficulty. Abnormality in liver function tests has been reported; almost one-half of patients experience different degrees of liver test abnormalitities. According to a recent study using single-cell RNA sequencing , angiotensin-converting enzyme（ACE）2 was highly expressed not only in type II alveolar epithelial cells, but also in bile duct cells. Importantly, recent studies confirmed that ACE2 receptor is the cell entry receptor of SARS-CoV-2.. . All these findings suggest that SARS-CoV-2 may infect the bile duct cells and cause the abnormal liver function in these patients. However, alkaline phosphatase (ALP), the bile duct injury marker, is not specific to COVID-19.

A recent study reported that moderate microvascular steatosis and mild lobular and portal activity were present in liver biopsy specimens, indicating that the liver injury could be caused by either SARS-CoV-2 infection or drug-induced liver injury. Currently, however, there are no data to determine whether abnormal liver function in COVID-19 patients is due to drug use or not. Given the highly contagious and pathogenic nature of SARS-CoV-2 and the high incidence of liver damage, an in-depth evaluation of liver function in COVID patients is urgently warranted. 

In this study, we retrospectively investigated the changes in liver function tests in SARS-CoV-2-infected patients from a single center in Shanghai, China, and compared the clinical features, medications and length of stay of COVID-19 patients with vs. those without liver damage. The purpose of this study is to clarify the clinical features of COVID-19-related liver damage, evaluate the association between current medications and liver damage, and provide a reference for clinical treatment of patients with COVID-19.