Bolangir, Odisha

Clinical Quick Reference

Liver Function Tests

Reading the pattern: liver enzymes and bilirubin

Remember C · A · O Chronic hepatitis Acute hepatitis Obstructive jaundice

Test

C Chronic hepatitis Long-standing hepatocellular injury

A Acute hepatitis Sudden hepatocellular injury

O Obstructive jaundice Cholestatic / post-hepatic block

ALTAlanine aminotransferase

Mild ↑

Marked ↑↑

Mild ↑

ASTAspartate aminotransferase

Mild ↑

Marked ↑↑

Mild ↑

ALPAlkaline phosphatase

Normal to mild ↑

Mild ↑

Marked ↑↑

GGTGamma-glutamyl transferase

Normal to mild ↑

Mild ↑

Marked ↑↑

Bilirubin – DirectConjugated, water-soluble

Usually normal*

Moderate ↑

Marked ↑↑

Bilirubin – IndirectUnconjugated, albumin-bound

Normal

Mild ↑

Normal to mild ↑

Hallmark

Persistent mild ALT/AST rise, usually under 5× ULN, for more than 6 months

ALT/AST often over 10× ULN; ALT ≥ AST in viral hepatitis

ALP over 3× ULN with a matching GGT rise; direct bilirubin dominates

Direct vs Indirect bilirubin

Which fraction is raised points to where the problem is

Red cell breakdownHaem → bilirubin

IndirectUnconjugated, to liver on albumin

Liver conjugatesUGT1A1 enzyme

DirectConjugated, into bile

Bile ducts → gutStool colour

Indirect-predominant rise Direct fraction under 20% of total bilirubin

• Pre-hepatic: haemolysis, Gilbert syndrome, physiological neonatal jaundice
• Not water-soluble, so no bilirubin in urine; urobilinogen may rise
• ALT, AST and ALP usually normal

Direct-predominant rise Direct fraction over 50% of total bilirubin

• Hepatic or post-hepatic: hepatitis, drug-induced cholestasis, stones, stricture, tumour
• Water-soluble, so dark urine; pale stools when bile flow is blocked
• Pair with the enzyme pattern above to separate A from O

Normal Mild Moderate Marked

ULN = upper limit of normal. *Direct bilirubin rises when chronic disease decompensates.
Reference ranges vary by laboratory.

Swaraj Hospital and Research Institute Bolangir, Odisha

For education. Interpret LFTs with history, examination and imaging; not a substitute for clinical assessment.