🧫 FIB-4 Index (Liver Fibrosis)
Calculate the FIB-4 index to non-invasively estimate advanced hepatic fibrosis.
FIB-4 Index (Liver Fibrosis)
Age (years)
AST (U/L)
ALT (U/L)
Platelets (×10⁹/L)
When to use
Triage for elastography or hepatology referral in NAFLD and viral hepatitis.
How it works
FIB-4 = (age × AST) / (platelets × √ALT). < 1.45 low; > 3.25 high probability of advanced fibrosis.
Key points
- Below the low cut-off, advanced fibrosis is unlikely.
- Less reliable under age 35 or over 65 (use a higher low cut-off ~2.0 in the elderly).
- Indeterminate results warrant further testing.
References
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.