Increases in liver enzymes are common in people with
COVID-19 and occur more frequently in people with severe COVID-19, a
meta-analysis of studies published in Hepatology International shows.
Most liver enzyme elevations were mild-to-moderate and did
not result in severe liver injury, the review found. Only one case of liver
failure was identified in the 128 studies reviewed.
Liver enzyme abnormalities were more likely to occur in
people with chronic liver disease, the meta-analysis found.
Two coronaviruses with genetic similarities to SARS-CoV-2
(SARS-CoV and MERS-CoV) are known to cause liver damage so physicians were
already alerted to the potential for liver injury when SARS-CoV-2 began to cause
life-threatening illness in China in early 2020.
Since the first cases of COVID-19 were reported, over 300
studies have been published that report on liver function abnormalities in
people with COVID-19. Researchers at Chandigarh University, India, carried out
a systematic review of these studies, rejecting published studies which
reported on less than five patients or where a diagnosis of COVID-19 was not
confirmed by virological testing, leaving 128 studies.
The investigators calculated the pooled prevalence of liver
function abnormalities reported in these studies:
- Hypoalbuminemia – 61.2% (48.2-72.8)
- GGT elevation – 27.9% (18.2-40.2)
- Acute hepatic injury – 23.7% (16.3-33.1)
- ALT elevation – 23.2% (19.9-27)
- AST elevation – 23.4% (18.8-28.7)
- Hyperbilirubinemia – 10.8% (95% CI 6.87-17.08)
- ALP – 7.48% (3.9-13.8).
With the exceptions of ALT and AST, the relative risk of an
abnormality was greater in people with severe COVID-19.
However, the review did not find a higher prevalence of
underlying liver disease in severe COVID-19 cases. The investigators warn that
the review cannot provide evidence on whether chronic liver disease places
people at higher risk of severe COVID-19, especially because the designation 'chronic liver disease' embraces viral hepatitis, metabolic disorders,
autoimmune disorders and other conditions.
When they compared the risk of liver abnormalities in people
with hepatitis B to other people with chronic liver disease, the investigators found
no increase in the risk of severe COVID-19 in people with hepatitis B. However,
fatty liver disease was associated with a higher risk of severe COVID-19 in
four out of five studies which reported on the association.
The investigators say it is impossible to tell whether liver
abnormalities are caused by the virus, by the immune system’s response to the
virus or by medications used to treat COVID-19, many of which cause liver
They also caution that most of the studies identified by the
review reported on Chinese patients, so the findings may not capture important underlying
differences between populations.