Calculators · Gastroenterology & Hepatology · Formula

FIB-4 index

Also called FIB4, Fibrosis-4

Age, AST, ALT and platelets to rule advanced fibrosis in or out in chronic liver disease.

years
IU/L
IU/L
×10⁹/L

Fill 4 more fields to see the result.

Formula and scoring

FIB-4 = (age × AST) ÷ (platelets [10⁹/L] × √ALT). Cut-offs < 1.45 and > 3.25.

Exam and ward pearls

  • Age is in the numerator, so FIB-4 rises with age alone.
  • Original cohort was HIV/HCV co-infection (Ishak 4–6); validated in HCV mono-infection by Vallet-Pichard.

When not to rely on it

  • Cut-offs were derived in viral hepatitis (HIV/HCV, HCV); do not transfer them unchanged to other liver diseases.

Source

  1. Sterling RK, Lissen E, Clumeck N, et al. Development of a simple noninvasive index to predict significant fibrosis in patients with HIV/HCV coinfection. Hepatology. 2006;43(6):1317-25. doi:10.1002/hep.21178 · PMID 16729309
  2. Vallet-Pichard A, Mallet V, Nalpas B, et al. FIB-4: an inexpensive and accurate marker of fibrosis in HCV infection. Comparison with liver biopsy and FibroTest. Hepatology. 2007;46(1):32-6. doi:10.1002/hep.21669 · PMID 17567829
  3. World Health Organization. Guidelines for the prevention, care and treatment of persons with chronic hepatitis B infection. Geneva: WHO; 2015. Chapter 4, Figure 4.1 and Table 4.3. Link

Formula and cut-offs checked against these sources on 8 Nov 2026. Educational tool for clinicians; it does not replace clinical judgement.

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