FIB-4 Index — Liver Fibrosis Assessment

The FIB-4 (Fibrosis-4) index is a non-invasive serum-based score for estimating liver fibrosis in patients with chronic liver disease, particularly hepatitis C, hepatitis B, and non-alcoholic fatty liver disease (NAFLD/MASLD). FIB-4 = (Age × AST) / (Platelet Count × √ALT) and performs consistently well across multiple chronic liver disease etiologies. It is the most widely validated non-invasive fibrosis marker for MASLD (metabolic dysfunction-associated steatotic liver disease).