Non-invasive assessment of hepatic fibrosis stage using age, AST, ALT, and platelet count.
When to use: Use FIB-4 in patients with chronic liver disease (hepatitis B, hepatitis C, NAFLD/MASLD, alcohol-related liver disease) to non-invasively assess the likelihood of advanced fibrosis. A FIB-4 <1.30 effectively rules out significant fibrosis (NPV ~90%), reducing the need for liver biopsy. Values >2.67 should prompt FibroScan (transient elastography) or liver biopsy for definitive staging. Particularly useful for annual monitoring in hepatitis B and NAFLD clinics.
FIB-4 uses four routine labs: age, AST, ALT, platelet count — no expensive biomarkers needed, making it ideal for Indian clinical settings.
Platelets fall in cirrhosis due to hypersplenism and reduced thrombopoietin production by the damaged liver.
AST:ALT ratio (De Ritis ratio) >2:1 suggests alcoholic hepatitis; in NAFLD, ALT > AST until late-stage fibrosis.
FIB-4 >2.67 has ~80% specificity for advanced fibrosis (F3–F4) — prompts FibroScan or biopsy.
NAFLD (now called MASLD) is the most common liver disease globally and in India — FIB-4 is endorsed by AASLD and EASL guidelines for its initial fibrosis assessment.
References
Sterling RK et al. Development of a simple noninvasive index to predict significant fibrosis in patients with HIV/HCV coinfection · Hepatology (2006)
Newsome PN et al. Guidelines on the management of abnormal liver blood tests · Gut (2018)
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