FIB-4 Calculator
Calculate FIB-4 — a non-invasive blood test score that predicts advanced liver fibrosis using age, AST, ALT and platelets.
What is FIB-4?
FIB-4, originally developed in 2006 for HIV/HCV co-infected patients, is now a widely used non-invasive marker of advanced liver fibrosis (stages F3–F4). It outperforms APRI in many studies and is recommended by the EASL and AASLD as a first-line screen in patients with non-alcoholic fatty liver disease, hepatitis B or C, and other chronic liver conditions.
How is it calculated?
FIB-4 = (Age × AST) / (Platelets × √ALT). Cut-offs vary by population: in NAFLD, < 1.3 (or 2.0 for over-65) excludes advanced fibrosis with high negative predictive value; > 2.67 strongly suggests advanced fibrosis. In hepatitis C, the upper cut-off is often 3.25.
Frequently Asked Questions
- Is FIB-4 better than APRI?
- Generally yes — FIB-4 has higher accuracy in mixed-aetiology populations.
- Should FIB-4 be repeated?
- Yes — annual repeat is reasonable in chronic liver disease.
- Can FIB-4 replace elastography?
- No — but it identifies who needs elastography or biopsy.
- What if FIB-4 is indeterminate?
- Pursue elastography or specialist referral.