Interpretation
| Result | Meaning |
|---|---|
| < 1.30 (< 2.0 if age ≥65) | Advanced fibrosis unlikely (NPV ~90%) |
| 1.30–2.67 | Indeterminate; second-line test |
| > 2.67 | Advanced fibrosis likely |
Formula
FIB-4 = age (years) × AST (U/L) ÷ [platelets (10⁹/L) × √ALT (U/L)]
Clinical pearls
- Unreliable under age 35; in age ≥65 use 2.0 as the low cut-off to avoid false positives (McPherson 2017).
- Original HCV/HIV cut-offs were 1.45 and 3.25; MASLD guidelines (AASLD 2023) use 1.3 and 2.67.
- Acute hepatitis or marked transaminase rises invalidate it.
Examples
fib-4 55 yo ast 45 alt 50 plt 210FIB-4 for a 68 year old with AST 60, ALT 40 and platelets 120fib4 age 50 ast 30 alt 35 platelets 250
FAQ
What is a normal FIB-4?
Below 1.3 (below 2.0 if 65 or older) makes advanced fibrosis unlikely in fatty liver disease.
What should I do with an indeterminate FIB-4?
Scores of 1.3–2.67 should get a second-line test such as transient elastography (FibroScan) or the ELF blood test.
Evidence
- Sterling RK et al. Development of a simple noninvasive index to predict significant fibrosis in patients with HIV/HCV coinfection. Hepatology 2006;43:1317–25.
- Shah AG et al. Comparison of noninvasive markers of fibrosis in patients with nonalcoholic fatty liver disease. Clin Gastroenterol Hepatol 2009;7:1104–12.
- McPherson S et al. Age as a confounding factor for the accurate non-invasive diagnosis of advanced NAFLD fibrosis. Am J Gastroenterol 2017;112:740–51.