Liver Markers: Standard Laboratory Assessment Panel
The core liver markers used to assess liver health are ALT, ALP, total bilirubin, albumin, and PT/INR, with ALT and ALP identifying the vast majority of adults with liver disease 1.
Standard Liver Blood Test Panel
According to the 2018 Gut guidelines, the essential markers fall into two main categories 1:
Hepatocellular Injury Markers
- Alanine aminotransferase (ALT/SGPT): Primary marker of hepatocyte damage, provides day-by-day assessment of liver cell injury
- Aspartate aminotransferase (AST/SGOT): Secondary marker of hepatocellular injury, less liver-specific than ALT
Cholestatic/Biliary Markers
- Alkaline phosphatase (ALP): Estimates impedance of bile flow; when elevated in isolation, requires γ-glutamyltransferase (GGT) measurement to confirm hepatic origin 1
- Total bilirubin: Best overall test of liver function, comprises conjugated and unconjugated fractions 1
Synthetic Function Markers
- Albumin: Produced exclusively by the liver, reflects synthetic capacity, though reduced in many non-hepatic conditions (sepsis, nephrotic syndrome, malabsorption) 1
- Prothrombin time (PT)/INR: Measures clotting factors (II, V, VII, IX, X) made in the liver; prolongation indicates significant injury (>70% synthetic function loss) 1
Additional Important Markers
- Platelet count: Most common hematological abnormality in chronic liver disease, indicates advanced disease through decreased production, splenic sequestration, and increased destruction 1
Clinical Interpretation Pitfalls
Critical caveat: Isolated elevated bilirubin with predominantly unconjugated fraction (absent hemolysis) is virtually always Gilbert's syndrome and requires only reassurance 1. However, in neonates/infants with conjugated bilirubin >25 μmol/L, urgent pediatric referral is essential 1.
Important limitation: Albumin should not be overinterpreted as a severity marker since concentrations decrease in sepsis, inflammatory disorders, and protein-losing conditions independent of liver function 1.
PT/INR prolongation can result from vitamin K deficiency in fat malabsorption and chronic cholestasis, not just hepatic dysfunction 1.
Emerging Biomarkers
While not part of standard panels, newer markers include HMGB1, cytokeratin 18, glutathione-S-transferase-α, glutamate dehydrogenase, and microRNAs, though these remain investigational 2.