What initial labs and tests to order if a CT (Computed Tomography) abdomen shows hepatomegaly (enlarged liver)?

Initial Laboratory and Imaging Workup for Hepatomegaly on CT Abdomen

Order a comprehensive hepatic function panel including AST, ALT, alkaline phosphatase, bilirubin, albumin, PT/INR, and CBC, along with hepatitis B and C serologies, to assess liver synthetic function and identify the underlying etiology of hepatomegaly. 1

Essential Laboratory Tests

Hepatic Function Assessment

• Liver enzymes: Measure AST, ALT, alkaline phosphatase, and lactate dehydrogenase to distinguish between hepatocellular injury (elevated transaminases) versus cholestatic patterns (elevated alkaline phosphatase) 1
• Bilirubin levels: Total and direct bilirubin provide the best overall assessment of liver function and help differentiate conjugated versus unconjugated hyperbilirubinemia 2, 3
• Synthetic function markers: Albumin, total protein, and PT/INR are critical for assessing hepatic reserve and distinguishing acute from chronic liver disease 1, 3
• Complete blood count: CBC helps identify thrombocytopenia (suggesting portal hypertension) and anemia (suggesting chronic disease or hemolysis) 1

Etiologic Workup

• Viral hepatitis serologies: Test for hepatitis B surface antigen (HBsAg) and hepatitis C antibody, as viral hepatitis is a major cause of hepatomegaly and chronic liver disease 1
• Renal function: BUN and creatinine are established prognostic markers in liver disease and essential for Child-Pugh scoring 1

Additional Imaging Considerations

When Ultrasound Is Indicated

• Order abdominal ultrasound if the initial CT was non-contrast or single-phase, as ultrasound effectively detects biliary dilatation, gallstones, and signs of cirrhosis with 65-95% sensitivity 4, 5
• Ultrasound provides additional information about hepatic parenchymal texture, portal vein patency, and presence of ascites without radiation exposure 4

When Advanced Imaging Is Needed

• Multiphase contrast-enhanced CT or MRI is appropriate if focal liver lesions are identified, particularly in patients with chronic liver disease or risk factors for hepatocellular carcinoma 1
• For lesions >1 cm in patients with chronic liver disease, either multiphase CT or MRI with contrast are equivalent alternatives per ACR guidelines 1
• Serum alpha-fetoprotein (AFP) should be added if there is concern for HCC, though it lacks sensitivity and specificity as a standalone test 1

Clinical Context Matters

Pattern Recognition

• Cytolytic pattern (elevated AST/ALT): Consider viral hepatitis, drug toxicity, alcoholic or non-alcoholic fatty liver disease, and hemochromatosis 2
• Cholestatic pattern (elevated alkaline phosphatase/GGT): Ultrasound becomes essential to distinguish extrahepatic biliary obstruction from intrahepatic cholestasis 2
• Normal synthetic function with hepatomegaly: Consider glycogen storage disease (especially in diabetics), infiltrative diseases, or early steatosis 6, 7

Common Pitfalls

• Do not rely on a single test; a panel approach (AST, alkaline phosphatase, bilirubin, albumin) provides superior sensitivity and specificity compared to individual tests 8
• Hepatomegaly with mildly elevated transaminases may represent hepatic steatosis, which requires different management than glycogenosis—distinction often requires histology if clinical context is unclear 6
• In diabetic patients with hepatomegaly and elevated liver enzymes, consider hepatic glycogenosis, which is reversible with glycemic control and does not progress to cirrhosis 6

Child-Pugh Scoring

• Calculate Child-Pugh score using albumin, bilirubin, PT/INR, and clinical assessment of ascites and encephalopathy to classify patients as compensated (Class A) versus decompensated (Class B/C) cirrhosis 1
• This scoring guides prognosis and treatment decisions, particularly for patients being considered for hepatocellular carcinoma treatment 1