🧫 FIB-4 Index (Liver Fibrosis)
Calculate the FIB-4 index to non-invasively estimate advanced hepatic fibrosis.
Clinical takeaway
Below the low cut-off, advanced fibrosis is unlikely.
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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.
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Age | 55 years |
|---|---|
| AST | 40 U/L |
| ALT | 30 U/L |
| Platelets | 200 ×10⁹/L |
→FIB-42.01
- Interpretation：Indeterminate — consider further testing
- Cut-offs：< 1.45 low · > 3.25 high (age > 65: use higher low cut-off ~2.0)
Frequently asked questions
- What is FIB-4 Index (Liver Fibrosis)?
- Calculate the FIB-4 index to non-invasively estimate advanced hepatic fibrosis.
- How is FIB-4 Index (Liver Fibrosis) calculated? What is the core formula?
- FIB-4 = (age × AST) / (platelets × √ALT). < 1.45 low; > 3.25 high probability of advanced fibrosis.
- When is FIB-4 Index (Liver Fibrosis) used?
- Triage for elastography or hepatology referral in NAFLD and viral hepatitis.
- What are the key clinical points for FIB-4 Index (Liver Fibrosis)?
- 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.
- What are the limits and cautions when using FIB-4 Index (Liver Fibrosis)?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is FIB-4 Index (Liver Fibrosis) calculated in practice? Can you show a worked example?
- Inputs: Age 55 years, AST 40 U/L, ALT 30 U/L, Platelets 200 ×10⁹/L → Result: FIB-4 2.01（Interpretation: Indeterminate — consider further testing, Cut-offs: < 1.45 low · > 3.25 high (age > 65: use higher low cut-off ~2.0)）