FIB-4 calculator online: non-invasive liver fibrosis assessment from biochemistry and platelets
FIB-4 index for screening advanced liver fibrosis (F3–F4) in NAFLD, HCV, HBV, and alcoholic liver disease. Formula: (age × AST) / (platelets × √ALT). >3.25 indicates high probability of advanced fibrosis – elastography or biopsy is warranted.
About this calculator
FIB-4 is a non-invasive liver fibrosis marker, developed by Sterling et al. (Hepatology, 2006) for HIV/HCV coinfection and later validated in HCV monoinfection, HBV, non-alcoholic fatty liver disease (NAFLD), and alcoholic liver disease. Formula: FIB-4 = (age × AST) / (platelets × √ALT), with age in years, AST and ALT in U/L, platelets in 10⁹/L. Used in hepatology, primary care, endocrinology, and infectious diseases to select patients for elastography (FibroScan) or liver biopsy. Interpretation: <1.30 rules out advanced fibrosis (F3–F4) with 90% negative predictive value; 1.30–3.25 is the gray zone requiring further workup; >3.25 indicates high probability of F3–F4 (positive predictive value ~65%) – elastography or biopsy is warranted. In patients over 65 a revised threshold of <2.0 for ruling out advanced fibrosis is recommended to avoid false positives. According to EASL 2024 and AASLD 2023 guidelines FIB-4 is the first-line screening tool in NAFLD in primary care. The formula does not work in acute hepatitis (distorted transaminases), thrombocytopenia of other etiologies (ITP, chemotherapy, hypersplenism), or pregnancy. In HIV patients on antiretroviral therapy hyperthrombocytopenia may underestimate FIB-4.
Source
Formula version: sterling-2006-aga-2023-v1
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