FIB-4 index
Rule out advanced liver fibrosis with routine blood tests (MASLD, viral hepatitis)
- EASL–EASD–EASO 2024 MASLD
Sources last checked: 2026-10-13
FIB-4 index
Rule out advanced liver fibrosis with routine blood tests (MASLD, viral hepatitis)
The 1.3 / 2.67 cut-offs come from MASLD studies; Sterling's original HIV/HCV cut-offs were 1.45 / 3.25. Unreliable under 35 years, and AST/ALT rise in acute hepatitis or alcohol use distorts it.
Interpretation
| < 1.3 — low risk | Advanced fibrosis unlikely; EASL–EASD–EASO 2024 foresees reassessment every 1–3 years if risk factors persist. |
|---|---|
| 1.3–1.99 — indeterminate (low if age > 65) | Under 65 years: indeterminate — EASL–EASD–EASO 2024 names elastography (e.g. VCTE) or a repeat after 1 year of risk-factor management as the next step. Over 65 years the lower cut-off is 2.0, so this range counts as low risk. |
| 2.0–2.66 — indeterminate | Indeterminate at any age; EASL–EASD–EASO 2024 foresees a second-line test such as liver elastography. |
| ≥ 2.67 — high risk | Advanced fibrosis likely; EASL–EASD–EASO 2024 foresees hepatology assessment / elastography for this group. |
What is the FIB-4 index?
FIB-4 combines age, AST, ALT and platelet count to estimate the probability of advanced liver fibrosis. Sterling et al. developed it in 2006 in patients co-infected with HIV and hepatitis C; it is now the recommended first-line non-invasive test in metabolic dysfunction-associated steatotic liver disease (MASLD).
When to use it
- Adults with type 2 diabetes, obesity with metabolic risk factors, or persistently raised transaminases
- Primary-care triage of suspected MASLD before referral
- Chronic viral hepatitis when elastography is not available
When not to use it
- Age under 35 years, where performance is poor
- Acute hepatitis or recent heavy alcohol intake (transaminases distorted)
- Thrombocytopenia from causes other than portal hypertension
How it is calculated
FIB-4 = (age × AST) ÷ (platelets × √ALT); age in years, AST and ALT in U/L, platelets in 10⁹/L.
Clinical pearls and limitations
- The 1.3 / 2.67 cut-offs come from MASLD studies; Sterling's original HIV/HCV cut-offs were 1.45 / 3.25. Unreliable under 35 years, and AST/ALT rise in acute hepatitis or alcohol use distorts it.
- EASL–EASD–EASO 2024: FIB-4 < 1.3 = low risk; > 2.67 = high risk; above 65 years the lower cut-off is 2.0.
- For the indeterminate range EASL–EASD–EASO 2024 foresees a second test, usually vibration-controlled transient elastography.
- Around 10 % of people with advanced fibrosis are missed by a low FIB-4.
- Use cut-offs that match the population: 1.45 / 3.25 were the original HIV/HCV thresholds.
Frequently asked questions
What FIB-4 value is normal?
Below 1.3 makes advanced fibrosis unlikely (below 2.0 in people over 65). Values of 2.67 or more suggest advanced fibrosis.
Why is there a different FIB-4 cut-off over 65?
Age is part of the formula, so older people score higher without having more fibrosis; EASL uses 2.0 as the lower cut-off above 65 years to avoid false positives.
What follows an indeterminate FIB-4?
EASL–EASD–EASO 2024 foresees a second-line test such as liver elastography, or a year of intensified risk-factor management followed by a repeat FIB-4.
Evidence and guidelines
- Primary source: Sterling RK et al. Development of a simple noninvasive index to predict significant fibrosis in patients with HIV/HCV coinfection. Hepatology 2006;43(6):1317-1325.
- EASL–EASD–EASO Clinical Practice Guidelines on the management of MASLD. J Hepatol 2024;81:492-542 (co-published Obes Facts 2024;17:374-444) — cut-offs 1.3 / 2.67, lower cut-off 2.0 above 65 years.
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