Which blood tests are helpful in the diagnosis of choledocholithiasis?

Updated: Apr 01, 2019
  • Author: Douglas M Heuman, MD, FACP, FACG, AGAF; Chief Editor: BS Anand, MD  more...
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Patients with cholangitis and pancreatitis have abnormal laboratory test values. Importantly, a single abnormal laboratory value does not confirm the diagnosis of choledocholithiasis, cholangitis, or pancreatitis; rather, a coherent set of laboratory studies leads to the correct diagnosis.

Choledocholithiasis with acute common bile duct (CBD) obstruction initially produces an acute increase in the level of liver transaminases (alanine and aspartate aminotransferases), followed within hours by a rising serum bilirubin level. The higher the bilirubin level, the greater the predictive value for CBD obstruction. CBD stones are present in approximately 60% of patients with serum bilirubin levels greater than 3 mg/dL.

If obstruction persists, a progressive decline in the level of transaminases with rising alkaline phosphatase and bilirubin levels may be noted over several days. Prothrombin time may be elevated in patients with prolonged CBD obstruction, secondary to depletion of vitamin K (the absorption of which is bile-dependent). Concurrent obstruction of the pancreatic duct by a stone in the ampulla of Vater may be accompanied by increases in serum lipase and amylase levels.

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