Abnormal liver tests linked with poor COVID-19 outcomes

Patients with the novel coronavirus (COVID-19) presented with abnormal liver tests at much higher rates than suggested by earlier studies, according to new research by Yale University published in the journal Hepatology. They also discovered that higher levels of liver enzymes, proteins released when the liver is damaged, were associated with poorer outcomes for these patients, including intensive care unit admission, mechanical ventilation, and death.

Previous studies in China found that approximately 15 percent of patients with COVID-19 had abnormal liver tests. The Yale study, which looked retrospectively at 1,827 COVID-19 patients who were hospitalized in the Yale New Haven Health system between March and April, found that the incidence of abnormal liver tests was between 41.6 percent and 83.4 percent of patients, depending on the specific test.

In all, the Yale researchers examined five liver tests, looking at factors such as elevations in aspartate aminotransferase (AST) and alanine transaminase (ALT), which indicate liver cell inflammation; an increase in bilirubin, which indicates liver dysfunction; and increased levels of alkaline phosphatase (ALP), which may indicate inflammation of bile ducts.

Although the researchers do not know why the incidence of abnormal liver tests was so much higher than in previous studies from China, Joseph Lim, MD, senior author and professor of medicine and director of the Yale Viral Hepatitis Program, said other health differences between the Chinese and U.S. populations could account for it.

The Yale researchers had access to patients' health records and were able to look at their liver tests prior to being diagnosed with COVID-19. Approximately one-quarter of patients in the study had abnormal liver tests prior to being admitted for the virus. Regardless of whether patients came to the hospital with existing liver problems or developed them during their COVID-19-related hospitalization, a strong association was observed between abnormal liver tests and the severity of the COVID-19 cases, the researchers said.

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