FIB 4
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Quick answer
FIB-4 (Fibrosis-4 index) is a simple, noninvasive score used to estimate the likelihood of significant liver fibrosis, especially in chronic hepatitis B/C, fatty liver disease, and alcohol-related liver disease.
[
\textbf{FIB-4} =
\frac{\text{Age (years)} \times \text{AST (U/L)}}{\text{Platelets (10}^9\text{/L)} \times \sqrt{\text{ALT (U/L)}}}
]
Common adult interpretation
- < 1.3: low likelihood of advanced fibrosis
- 1.3 to 2.67: indeterminate, consider further assessment such as transient elastography (FibroScan) or ELF test
- > 2.67: higher likelihood of advanced fibrosis, specialist evaluation is usually appropriate
For adults over 65, a higher low-risk cutoff, often 2.0, is commonly used to reduce false-positive results.
Important limits
- It is a screening/risk-stratification tool, not a diagnosis.
- AST/ALT can be temporarily high from acute hepatitis, alcohol use, strenuous exercise, or some drugs, which can distort the score.
- Not generally reliable in acute illness or in younger adults.
- The platelet count must be in 10⁹/L. A value reported as 150,000/µL equals 150 × 10⁹/L.
If you provide age, AST, ALT, and platelet count, I can calculate the FIB-4.
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