What lab values are recommended for patients with suspected cholangitis?

Laboratory Values in Suspected Cholangitis

In patients with suspected cholangitis, a comprehensive laboratory panel should include liver function tests (alkaline phosphatase, bilirubin, GGT, aminotransferases), inflammatory markers (WBC, CRP), and coagulation studies, as these values help establish diagnosis, assess severity, and guide management decisions. 1

Essential Laboratory Tests

Liver Function Tests

• Alkaline phosphatase (ALP): Typically elevated and often the first abnormal value; should be confirmed to be of hepatobiliary origin 1
• Gamma-glutamyl transferase (GGT): Elevated, helps confirm hepatobiliary origin of ALP elevation 1
• Bilirubin:
  • Total bilirubin should be fractionated to determine direct (conjugated) component 1
  • Levels are typically elevated but may be normal in early disease
  • Values >4 mg/dL suggest high likelihood of common bile duct stones 2
• Aminotransferases (ALT, AST):
  • Usually mildly elevated (<300 U/L) 1
  • May be markedly raised in acute obstruction or cholangitis 1

Inflammatory Markers

• Complete blood count: Leukocytosis is common 3
• C-reactive protein (CRP): Elevated in inflammatory conditions 1
• White blood cell count: Typically elevated, indicates systemic infection 4

Coagulation Studies

• Prothrombin time/INR: May be prolonged due to vitamin K malabsorption from prolonged biliary obstruction 1

Additional Recommended Tests

Immunoglobulin Testing

• IgG4 levels: Should be tested at screening to exclude IgG4-associated sclerosing cholangitis 1

Autoantibody Testing

• Antinuclear antibody (ANA) and anti-smooth muscle antibody (ASMA): Should be established at baseline to exclude overlap syndrome with autoimmune hepatitis 1
• p-ANCA: Often present but has low specificity 1

Tumor Markers (when malignancy is suspected)

• CA 19-9: Elevated in up to 85% of patients with cholangiocarcinoma; values >100 U/ml have 75% sensitivity and 80% specificity 1
• CEA: Raised in approximately 30% of cholangiocarcinoma patients 1
• CA-125: Elevated in 40-50% of cholangiocarcinoma cases 1

Laboratory Findings by Severity

Mild Cholangitis (Grade I)

• Mild elevations in liver enzymes
• Mild leukocytosis
• Normal or slightly elevated bilirubin

Moderate Cholangitis (Grade II)

• More pronounced elevations in liver enzymes
• Significant leukocytosis
• Elevated bilirubin

Severe Cholangitis (Grade III)

• Marked elevations in liver enzymes
• High leukocytosis
• Significantly elevated bilirubin
• Evidence of organ dysfunction (elevated creatinine, abnormal coagulation) 4

Clinical Pearls and Pitfalls

• Pitfall: Normal ALP does not exclude cholangitis; some patients may present with typical findings on cholangiography without ALP elevation 1
• Pearl: Persistently elevated CA 19-9 after biliary decompression suggests malignancy 1
• Pitfall: Elevated liver enzymes in PSC naturally fluctuate, making differentiation from acute cholangitis challenging 1
• Pearl: Fractionating bilirubin helps determine the percentage derived from direct (conjugated) bilirubin, which is elevated in obstructive processes 1

Monitoring Recommendations

• Follow liver function tests every 6-12 months depending on risk stratification 1
• Monitor for development of complications including cholangiocarcinoma with appropriate imaging and laboratory tests 1

Laboratory values should be interpreted in conjunction with clinical presentation and imaging findings to establish diagnosis and guide appropriate management of cholangitis.