How often is the liver affected by Covid-19?

Abnormal liver enzymes in patients with Covid-19 are common, particularly in those with severe disease.

 
Elevated levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) have been reported in 14-53% of patients in several case series. More severe cases appear to have a higher prevalence of AST elevation (1). As some cases also have elevated creatine kinase (CK), the relative contribution of muscles to these enzyme abnormalities is unclear (2).

 
A small study involving ICU patients with Covid-19 reported a prevalence of elevated AST of 62% compared to 25% in non-ICU patients (3). Other studies have confirmed lower incidence of AST abnormality among patients with mild or subclinical disease (4,5).

 
Although much of the published reports of liver injury in Covid-19 have revolved around AST and ALT abnormalities, gamma-glutamyl transferase (GGT) may also be elevated. GGT was abnormal in 54% of patients with Covid-19 during their hospitalization with alkaline phosphatase elevation reported in ~2.0% (1, unpublished reports). Elevation of total bilirubin has also been reported occasionally (1).

 
Although the exact mechanism(s) of Covid-19-related is unclear, direct viral infection of liver cells is one possibility as viremia has been documented in some cases (1). Of interest, a related coronavirus, SARS-CoV-1 has been shown to infect liver tissue and cholangiocytes may express ACE2 receptors, a prime target for Covid-19 virus (1,6,7, unpublished reports).

 

Despite these observations, to date, viral inclusions have not been demonstrated in the liver. Other possible causes of liver injury in Covid-19 include innate immune dysregulation, cytokine storm, hypoxia and drugs (1,2).

 

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References
1. Zhang C, Shi L, Wang FS. Liver injury in COVID-19:management and challenges. Lancet Gastroenterol Hepatol 2020; March 4. https://doi.org/10.1016/S2468-1253(20)30057-1
2. Bangash MN, Patel J, Parekh D. COVID-19 and the liver: little cause for concern. Lancet Gastroenterol Hepatol 2020;March 20. https://doi.org/10.1016/52468-1253(20)30084-4
3. Huang C, Wang Y, Li X, et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet 2020;395:497-506. https://pubmed.ncbi.nlm.nih.gov/31986264/
4. Guan WJ, Ni ZY, Hu Y, et al. Clinical characteristics of 2019 novel coronavirus infection in China. N Engl J Med 2020;published online Feb 28. DOI:10.1056/NEJMoa2003032
5. Shi H, Han X, Jiang N, et al. Radiological findings from 81 patients with COVID-19 pneumonia in Wuhan, China: a descriptive study. Lancet Infect Dis 2020; published onlineFeb 24. DOI:10.1016/S1473-3099(20)30086-4 (lancet 8)
6. Chai X, Hu L, Zhang Y, et al. Specific ACE2 expression in cholangiocytes may cause liver damage after 209-nCoV infection. bioRxiv 2020;published online Feb 4. https://doi.org/10.1101/2020.02.03.931766.
7. Xu Z, Shi L, Wang Y, et al. Pathological findings of COVID-19 associated with acute respiratory distress syndrome. Lancet Respir Med 2020; published online Feb 18. DOI:10.1016/S2213-2600(20)30076-X

 

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Massachusetts General Hospital, Harvard Catalyst, Harvard University, its affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

 

How often is the liver affected by Covid-19?

Can the elevation of AST and ALT in my patient with rhabdomyolysis be related to the muscle injury itself?

Yes! Elevated serum AST and ALT in the setting of rhabdomyolysis is not uncommon and, at least in some cases, appears to be related to the skeletal muscle injury itself.1,2

In a study of 16 patients considered to have significant muscle necrosis due to extreme exercise, polymyositis or seizures without evidence of liver disease (eg, viral hepatitis, exposure to hepatotoxic drugs, heart failure, biliary tract disease, recent hypotension) AST and, to lesser degree, ALT was elevated. For extreme exercise, the median AST and ALT concentrations were 2,466 IU/L and 497 U/L, respectively, while for seizures these levels were 1,448 U/L and 383 U/L respectively.1  

Another study reported AST elevation (>40 U/L) in 93.1% of patients with rhabdomyolysis and ALT elevation (>40 U/L) in 75.0% of patients with serum creatine kinase ≥1000 U/L. Further supporting a skeletal muscle origin for AST elevation was the finding that AST concentrations fell in parallel with CK drop during the first 6 days of hospitalization for rhabdomyolysis. It was posited that ALT concentrations dropped slower because of its longer serum half-life (47 hours vs 17 hours for AST).2 Despite these findings, concurrent liver injury as an additional source of AST or ALT elevation cannot be excluded.

Elevation of AST and ALT with muscle injury should not come as a surprise. AST is found in heart and skeletal muscle among many other organs. Even ALT which is considered more specific to liver is found in organs such as skeletal muscle, heart and kidney, though at lower concentrations.3

Bonus Pearl: Did you know that the first description of rhabdomyolysis in the literature involved English victims of crush injuries during World War II?2

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References

  1. Nathwani RA, Pais S, Reynolds TB, et al. Serum alanine aminotransferase in skeletal muscle diseases. Hepatology 2005;41:380-82. https://www.ncbi.nlm.nih.gov/pubmed/15660433
  2. Weibrecht K, Dayno M, Darling C, et al. Liver aminotransferases are elevated with rhabdomyolysis in the absence of significant liver injury. J Med Toxicol 2010;6:294-300. https://link.springer.com/article/10.1007%2Fs13181-010-0075-9
  3. Giannini EG, Testa R, Savarino V. Liver enzyme alteration: a guidance for clinicians. CMAJ2005;172:367-79. Giannini EG, Testa R, Savarino V. Liver enzyme alteration: a guidance for clinicians. CMAJ 2005;172:367-79. https://www.ncbi.nlm.nih.gov/pubmed/15684121
Can the elevation of AST and ALT in my patient with rhabdomyolysis be related to the muscle injury itself?

What’s causing an isolated GGT elevation in my patient with an abnormal alkaline phosphatase on her routine admission lab?

Although serum gamma-glutamyl transpeptidase or GGT is a very sensitive test for liver disease, especially of biliary origin, it’s by no means a very specific test. Besides the liver, GGT is found in the kidneys, pancreas, prostate, heart, brain, and seminal vesicles but not in bone (1-4).

 
Obesity, alcohol consumption and drugs are common causes of GGT elevation (2). As early as 1960s, elevated GGT was reported in such seemingly disparate conditions as diabetes mellitus, congestive heart failure, myocardial infarction, nephrotic syndrome and renal neoplasm (3). Nonalcoholic steatohepatitis, viral hepatitis, biliary obstruction, COPD, liver metastasis, drug-induced liver injury can all cause GGT elevation (1-4).

 
An isolated GGT does not necessarily indicate serious or progressive liver disease. That’s one reason it’s often not included in routine “liver panel” lab tests (1).

What to do when GGT is high but other liver panel tests such as ALT, AST, albumin, and bilirubin are normal? If your patient is at risk of acquired liver disease, then further workup may be necessary (eg, hepatitis B and C screening tests). Alcohol consumption should be queried. Don’t forget conditions associated with iron overload. If your patient is obese, diabetic or has elevated both lipids, an ultrasound of the liver to look for fatty liver should be considered. In the absence of risk factors, symptoms, or physical exam suggestive of liver disease, isolated GGT elevation should not require further investigation (1).

 
One good thing that may come out of finding an isolated elevated GGT is to encourage your patient to curb alcohol consumption or lose weight when indicated. But don’t rely on a normal GGT to rule out heavy alcohol consumption as it may miss 70% to 80% of cases (6)! 

 
Bonus Pearl: Did you know that GGT activity is thought to increase in alcohol use due to its role in maintaining intracellular glutathione, an anti-oxidant, at adequate levels to protect cells from oxidative stress caused by alcohol?

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References

1. Carey WD. How should a patient with an isolated GGT elevation be evaluated? Clev Clin J Med 2000;67:315-16. https://www.ncbi.nlm.nih.gov/pubmed/10832186
2. Newsome PN, Cramb R, Davison SM, et al. Guidelines on the management of abnormal liver blood tests. Gut 2018;67:6-19. https://gut.bmj.com/content/gutjnl/67/1/6.full.pdf
3. Whitfield JB, Pounder RE, Neale G, et al. Serum gamma-glutamyl transpeptidase activity in liver disease. Gut 1972;13:702-8. https://www.ncbi.nlm.nih.gov/pubmed/4404786
4. Tekin O, Uraldi C, Isik B, et al. Clinical importance of gamma glutamyltransferase in the Ankara-Pursaklar region of Turkey. Medscape General Medicine 2004;6(1):e16. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1140713/
5. Van Beek JHDA, de Moor MHM, Geels LM, et al. The association of alcohol intake with gamma-glutamyl transferase (GGT) levels:evidence for correlated genetic effects. Drug Alcohol Depend 2014;134:99-105. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3909645/

6. Bertholet N, Winter MR, Cheng DM, et al. How accurate are blood (or breath) tests for identifying self-reported heavy drinking among people with alcohol dependence? Alcohol and Alcoholism 2014;49:423-29. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4060735/pdf/agu016.pdf

What’s causing an isolated GGT elevation in my patient with an abnormal alkaline phosphatase on her routine admission lab?