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FIB-4 (liver fibrosis)

A non-invasive index using age, AST, ALT and platelets to estimate the likelihood of advanced liver fibrosis. It is the recommended first step in fibrosis screening for steatotic liver disease.

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Check the population, units and version. The result shows the formula or classification; it does not make an automatic treatment decision.

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Method · Limits of application

FIB-4/Sterling 2006; HCV/HIV thresholds 1.45/3.25 versus MASLD 1.3/2.67 and age ≥65 years 2.0

Sterling’s 2006 FIB-4 was developed in patients with HIV/HCV coinfection, with <1.45 and >3.25 cutoffs assessed against Ishak 4–6 fibrosis. The formula uses age in years, AST and ALT in U/L and platelets in 10^9/L. Those cutoffs and the original population are not automatically interchangeable with MASLD criteria or age adjustments; those variants require their own sources.

Conditions of use

Check the population, units, inclusion and exclusion criteria, and version in the original source. A result alone does not establish a diagnosis, discharge decision or prescription.

Documented parameters

Age · years
Aspartate aminotransferase (AST) · U/L
Alanine aminotransferase (ALT) · U/L
Platelets · × 10³/mm³
Context

5/5 reference cases checked. Numerical tests are not clinical validation.

Sources and documentation

Documented formula

Transcribed from the source or a recorded revision; this is not a clinical recommendation.

FIB-4 = (age × AST) ÷ (platelets [10⁹/L] × √ALT).

MASLD: < 1.30 rules out advanced fibrosis (< 2.0 from age 65); > 2.67 suggests advanced fibrosis. Hepatitis C/HIV: < 1.45 and > 3.25.

References

Identifier: fib-4

Original clinical content: Brazilian Portuguese.

Method version

FIB-4/Sterling 2006; HCV/HIV thresholds 1.45/3.25 versus MASLD 1.3/2.67 and age ≥65 years 2.0

fib-4@native-2026-10-03+c69e33ae5d22

Source for the active edition

The bibliographic edition identifies the source. By itself, it proves neither full conformity of the formula nor clinical approval.

Synthetic cases checked (5)

Synthetic cases for checking the implementation, with no patient data.

Case 1

reference-001

Inputs

Age: 45 years
Aspartate aminotransferase (AST): 25 U/L
Alanine aminotransferase (ALT): 25 U/L
Platelets: 250 × 10³/mm³
Context: Steatosis (MASLD/NAFLD)

{
  "idade": 45,
  "ast": 25,
  "alt": 25,
  "plq": 250,
  "etio": "masld"
}

Expected result

{
  "fib4": 0.9
}

Actual result

{
  "fib4": 0.9
}

Case 2

reference-002

Inputs

Age: 50 years
Aspartate aminotransferase (AST): 40 U/L
Alanine aminotransferase (ALT): 36 U/L
Platelets: 200 × 10³/mm³
Context: Steatosis (MASLD/NAFLD)

{
  "idade": 50,
  "ast": 40,
  "alt": 36,
  "plq": 200,
  "etio": "masld"
}

Expected result

{
  "fib4": 1.6667
}

Actual result

{
  "fib4": 1.666667
}

Case 3

reference-003

Inputs

Age: 50 years
Aspartate aminotransferase (AST): 40 U/L
Alanine aminotransferase (ALT): 36 U/L
Platelets: 200 × 10³/mm³
Context: Hepatitis C or HIV/HCV

{
  "idade": 50,
  "ast": 40,
  "alt": 36,
  "plq": 200,
  "etio": "viral"
}

Expected result

{
  "fib4": 1.6667
}

Actual result

{
  "fib4": 1.666667
}

Case 4

reference-004

Inputs

Age: 70 years
Aspartate aminotransferase (AST): 30 U/L
Alanine aminotransferase (ALT): 25 U/L
Platelets: 200 × 10³/mm³
Context: Steatosis (MASLD/NAFLD)

{
  "idade": 70,
  "ast": 30,
  "alt": 25,
  "plq": 200,
  "etio": "masld"
}

Expected result

{
  "fib4": 2.1
}

Actual result

{
  "fib4": 2.1
}

Case 5

reference-005

Inputs

Age: 60 years
Aspartate aminotransferase (AST): 80 U/L
Alanine aminotransferase (ALT): 49 U/L
Platelets: 120 × 10³/mm³
Context: Steatosis (MASLD/NAFLD)

{
  "idade": 60,
  "ast": 80,
  "alt": 49,
  "plq": 120,
  "etio": "masld"
}

Expected result

{
  "fib4": 5.714
}

Actual result

{
  "fib4": 5.714286
}

Code and reproducibility

This tool’s code on GitHub

Download code and tests

Sources, version and reproduction instructions

The code tests are technical checks. Clinical approval and professional translation review are recorded separately.

Relationship with cancer research

General context — relationship to be defined

A resource for general clinical contexts. This edition does not assign a specific oncological relationship; selecting it for a study requires a justified question, population and purpose.