Although markedly increased serum alanine transaminase (ALT) and aspartate transaminase (AST) are often considered a marker for severe hepatocellular injury or necrosis (particularly when levels exceed 1000 IU/L), occasionally such elevations may also be due to isolated acute biliary duct obstruction caused by choledocholithiasis^.1 

In one case series, patients  diagnosed with choledocholithiasis were found to have transient elevations in their AST/ALT (>1000 units/L) directly proportional to the degree of common bile duct dilation in the absence of any hepatocellular disease on imaging. These levels were found to rapidly fall following intervention with endoscopic retrograde cholangiopancreatography (ERCP). ²  Intriguingly, the authors of this study suggest that patients who present with severe abdominal pain associated with an acute and markedly elevated serum aminotransferase levels, are more likely to have acute biliary obstruction than hepatocellular disease.³ Several other case series have also shown similar elevations of serum aminotransferases in choledocholithiasis, with some levels reaching >2000 IU/L.⁴ 

Several hypotheses have been proposed to explain this phenomenon, including pressure-induced damage of hepatocytes and bile salt-induced hepatocyte injury in the setting of acute biliary duct obstruction.² Of interest, some have proposed that the gallbladder may minimize elevations in serum aminotransferases by protecting the liver from rapid increases in biliary duct pressure.  In fact, more robust elevations in aminotransferases in choledocholithiasis have been observed in those who have had cholecystectomy.⁴ 

So even though choledocholithiasis is traditionally associated with a “cholestatic” pattern of enzyme elevations—with elevated alkaline-phosphatase, and gamma-glutamyl transferase (GGT) levels ^1,3—when associated with bile duct obstruction, it  can also be associated with markedly elevated ALT and AST.  

Bonus Pearl: Did you know that when assessing for choledocholithiasis, magnetic resonance cholangiopancreatography (MRCP) is more sensitive than ultrasound (81% vs 18-74 %).^4,5,6 

Contributed by Connor S. Shaw, D.O., Mercy Hospital, St. Louis, Missouri

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References  

1. Feldman, Mark, et al. Sleisenger and Fordtran’s Gastrointestinal and Liver Disease: Pathophysiology, Diagnosis, Management. Elsevier, 2021.  
2. Tetangco, Eula Plana, et al. “Markedly Elevated Liver Enzymes in Choledocholithiasis in the Absence of Hepatocellular Disease.” Journal of Investigative Medicine High Impact Case Reports, vol. 4, no. 2, 2016, p. 232470961665109., https://doi.org/10.1177/2324709616651092. 
3. De Angelis C, Marietti M, Bruno M, Pellicano R, Rizzetto M. Endoscopic ultrasound in common bile duct dilatation with normal liver enzymes. World J Gastrointest Endosc. 2015 Jul 10;7(8):799-805. doi: 10.4253/v7.i8.799. PMID: 26191344; PMCID: PMC4501970.
4. Agahi, A., and A. McNair. “Choledocholithiasis Presenting with Very High Transaminase Level.” Case Reports, vol. 2012, no. nov22 2, 2012, https://doi.org/10.1136/bcr-2012-007268.
5. Makmun, Dadang, et al. “Sensitivity and Specificity of Magnetic Resonance Cholangiopancreatography versus Endoscopic Ultrasonography against Endoscopic Retrograde Cholangiopancreatography in Diagnosing Choledocholithiasis: The Indonesian Experience.” Clinical Endoscopy, vol. 50, no. 5, 2017, pp. 486–490., https://doi.org/10.5946/ce.2016.159.
6. Ferri, João Victor, et al. “Níveis Elevados De Transaminases Em Um Caso De Coledocolitíase: A Importância Do Reconhecimento Deste Padrão.” Revista De Medicina, vol. 96, no. 2, 2017, p. 131., https://doi.org/10.11606/issn.1679-9836.v96i2p131-133.   

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their 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!