What labs should be ordered for a patient with suspected gallbladder disease?

Laboratory Evaluation for Suspected Gallbladder Disease

Order a comprehensive metabolic panel including liver function tests (ALT, AST, alkaline phosphatase, total and direct bilirubin, GGT), complete blood count with differential, and prothrombin time for all patients with suspected gallbladder disease. 1

Essential Laboratory Tests

The following tests form the core workup and should be ordered together:

• Liver enzymes (ALT and AST): These assess hepatocellular injury and help identify common bile duct stones, with ALT being particularly sensitive for biliary obstruction 1, 2

• Alkaline phosphatase (ALP): This demonstrates 92% sensitivity and 79% specificity for common bile duct stones at a cut-off >125 IU/L, making it one of the most reliable markers 1

• Gamma-glutamyl transferase (GGT): This has the highest sensitivity (83%) for detecting common bile duct stones among all liver function tests 1, 3

• Total and direct bilirubin: Direct bilirubin has 79% sensitivity for common bile duct stones, with a cut-off of 22.23 μmol/L providing 84% sensitivity and 91% specificity 1

• Complete blood count: The neutrophil count is statistically associated with acute cholecystitis diagnosis and helps assess the inflammatory response 1, 2

• Prothrombin time: This is mandatory before any potential biliary sphincterotomy or intervention 1

Risk Stratification Based on Laboratory Results

Use the following algorithm to determine next steps after obtaining labs:

Low Risk (<10% probability of common bile duct stones):

• Normal or minimally elevated liver function tests
• Proceed directly to cholecystectomy without additional imaging 1

Moderate Risk (10-50% probability):

• GGT 90-180 units/L
• Mildly elevated liver function tests
• Obtain MRCP or endoscopic ultrasound before surgical intervention 1

High Risk (>50% probability):

• Bilirubin >twice the upper limit of normal
• ALP >250 IU/L
• GGT >180 units/L
• Proceed directly to ERCP for diagnosis and therapeutic intervention 1

Important Caveats and Pitfalls

False positives and negatives are common, particularly in specific clinical contexts:

• In acute cholecystitis, elevated liver function tests have a positive predictive value of less than 40% for common bile duct stones, making them less reliable in this setting 3, 4

• Bilirubin >twice normal has 97% specificity but only 42% sensitivity for common bile duct stones, meaning normal bilirubin does not exclude stones 1

• In patients with a history of pancreatitis or cholecystitis, other mechanisms beyond bile duct stones may cause elevated liver enzymes, reducing the predictive accuracy 4

• 93% of patients with completely normal liver function tests will have a normal intraoperative cholangiogram, making additional biliary imaging unnecessary in this group 4

Monitoring During Treatment

For patients receiving antibiotic therapy for cholecystitis:

• Monitor clinical conditions and inflammation indices to guide treatment duration 1

• Patients with ongoing signs of infection or systemic illness beyond 7 days of antibiotic treatment require repeat diagnostic investigation 1