FIB-4 Index
FIB-4 = (Age × AST) / (Platelets × √ALT); platelets in ×10⁹/L; AST/ALT in U/L.
Calculator
How it works
FIB-4 is a non-invasive index of liver fibrosis using age, AST, ALT, and platelet count (Sterling 2006; published reference).
Limits
Performance varies by etiology (HBV, HCV, NAFLD) and age; not a substitute for elastography when available.
Educational tool only—not for diagnosis or treatment decisions.