Diagnostic Approach to Hyperbilirubinemia

Initial Evaluation

• The American College of Radiology recommends ordering fractionated bilirubin levels to determine if the hyperbilirubinemia is predominantly conjugated or unconjugated, which is crucial for narrowing down the differential diagnosis 1
• Complete liver function tests, including ALT, AST, ALP, and GGT, should be obtained to assess for liver injury and cholestasis 1
• Measure albumin and prothrombin time/INR to evaluate liver synthetic function 1

Special Considerations for Unconjugated Hyperbilirubinemia

• Evaluate for hemolysis with reticulocyte count, haptoglobin, and LDH 1
• Consider testing for Gilbert syndrome, which affects approximately 5% of the population and causes transient increases in unconjugated bilirubin 2, 3
• Test for glucose-6-phosphate dehydrogenase (G6PD) deficiency, especially in patients of African, Mediterranean, or Asian descent 2, 4

Special Considerations for Conjugated Hyperbilirubinemia

• Abdominal ultrasound should be performed as the initial imaging study to evaluate for biliary obstruction 1, 2, 3
• Urinalysis and urine culture should be considered to rule out infection, especially if there are clinical signs of sepsis 4
• Consider viral hepatitis panel (HAV-IgM, HBsAg, HBcIgM, HCV antibody) 5
• Autoimmune markers may be indicated if other causes are ruled out 5

Diagnostic Algorithm

• Determine if hyperbilirubinemia is conjugated or unconjugated 1
• For unconjugated hyperbilirubinemia, focus on hemolysis workup and genetic disorders 1
• For conjugated hyperbilirubinemia, focus on hepatocellular damage and biliary obstruction 1
• If initial workup is inconclusive and bilirubin remains elevated for ≥6 months, consider liver biopsy 5

Common Pitfalls to Avoid

• Failing to fractionate bilirubin, which is essential for determining the underlying cause 1
• Overlooking medication-induced hyperbilirubinemia (common culprits include certain medications) 2, 3
• Delaying appropriate imaging in patients with conjugated hyperbilirubinemia, as early identification of biliary obstruction is critical 1
• Misinterpreting isolated mild hyperbilirubinemia, which may represent benign conditions like Gilbert syndrome 2, 3