How do you interpret FIB-4 results?

FIB-4 90%. FIB-4 1.30–2.67: Indeterminate, further testing recommended (elastography or other fibrosis markers). FIB-4 > 2.67: High probability of advanced fibrosis/cirrhosis. In patients over 65, adjusted cutoffs (< 2.0 for low risk) may be more appropriate.

When should FIB-4 be used?

FIB-4 is recommended as a first-line non-invasive test for fibrosis screening in NAFLD/NASH and chronic hepatitis C. The AASLD and AGA recommend using FIB-4 to risk-stratify patients and determine who needs further evaluation with liver elastography or referral to hepatology.

Back to all tools

Home / FIB-4 Index

FIB-4 Index (Liver Fibrosis)

Non-invasive assessment of hepatic fibrosis using age, AST, ALT, and platelet count. Recommended as a first-line screening tool for NAFLD/MASLD.

Inputs

Age (years)

AST (U/L)

ALT (U/L)

Platelet Count (× 10⁹/L)

—

Enter values to calculate FIB-4.

< 1.30Low risk — advanced fibrosis excluded (NPV ~90%)

1.30–2.67Indeterminate — consider further testing (FibroScan, ELF)

> 2.67High risk — advanced fibrosis likely (PPV ~65%)

For patients ≥ 65 years, some guidelines suggest adjusted cutoffs: low risk < 2.0, high risk > 2.67.

Disclaimer: For educational purposes only. Not a substitute for clinical judgment.

When to use

FIB-4 is recommended as a first-line non-invasive test (NIT) for risk stratification of liver fibrosis in patients with chronic liver disease, particularly NAFLD/MASLD and hepatitis C. It uses readily available labs and requires no specialized testing.

Clinical pearls

Formula: FIB-4 = (Age × AST) / (Platelet count × √ALT)
Best validated for ages 35–65. Less reliable in patients < 35 or > 65.
FIB-4 < 1.30 has an NPV of ~90% for excluding advanced fibrosis (F3–F4).
Indeterminate results (1.30–2.67) should prompt FibroScan or ELF test.
Part of the AGA Clinical Care Pathway for NAFLD screening.

References

Sterling RK, et al. Development of a simple noninvasive index to predict significant fibrosis in patients with HIV/HCV coinfection. Hepatology. 2006;43(6):1317-1325.
Shah AG, et al. Comparison of noninvasive markers of fibrosis in patients with NAFLD. Clin Gastroenterol Hepatol. 2009;7(10):1104-1112.

Related tools

About This Tool

What Is the FIB-4 Index?

The FIB-4 Index is a non-invasive scoring system that estimates the degree of liver fibrosis. Originally developed for HIV/HCV coinfected patients by Sterling et al. in 2006, it has since been extensively validated for NAFLD, hepatitis B, hepatitis C, and alcoholic liver disease. It uses four readily available parameters: age, AST, ALT, and platelet count.

The Formula

FIB-4 = (Age [years] × AST [U/L]) / (Platelet count [× 10⁹/L] × √ALT [U/L])

Clinical Application

FIB-4 is recommended by the AGA, AASLD, and EASL as a first-line screening tool in the non-invasive assessment pathway for liver fibrosis. A low FIB-4 (< 1.30) effectively excludes advanced fibrosis, while a high FIB-4 (> 2.67) suggests advanced fibrosis and should prompt hepatology referral. Indeterminate scores warrant second-line testing such as vibration-controlled transient elastography (FibroScan) or the Enhanced Liver Fibrosis (ELF) test.

🔑 Clinical Pearls

FIB-4 is the #1 recommended first-line NIT for NAFLD/MASLD fibrosis screening (AGA 2023 pathway).
Serial FIB-4 can be used to monitor fibrosis progression over time.
Platelet count alone is a useful surrogate — counts < 150 in chronic liver disease suggest portal hypertension/cirrhosis.
FIB-4 may overestimate fibrosis in elderly patients (age is in the numerator).

Key References

Sterling RK, et al. Development of a simple noninvasive index to predict significant fibrosis. Hepatology. 2006;43(6):1317-1325.
Kanwal F, et al. AGA Clinical Practice Update on screening and surveillance for hepatocellular carcinoma in patients with NAFLD. Gastroenterology. 2023;164(7):1626-1639.

Formula last verified: February 2026