Metabolic And Cardiovascular Obesity Scores

FIB-4 Score Calculator (for NAFLD-related CV risk)

Clinical calculation support · Verify results before clinical use

Calculate liver fibrosis index

Enter age, aminotransferases, and platelet count to calculate FIB-4. Use results as a fibrosis risk assessment, not as a standalone cardiovascular risk score.

About FIB-4

FIB-4 is a non-invasive index used to estimate the likelihood of advanced liver fibrosis using age, AST, ALT, and platelet count. It is commonly used as an initial risk-stratification test in people with suspected or established metabolic dysfunction-associated steatotic liver disease (MASLD, formerly NAFLD).

Formula

FIB-4 = (Age × AST) ÷ (Platelet count × √ALT)

Age is in years; AST and ALT are in U/L; platelet count is in 10⁹/L.

Usual adult interpretation

FIB-4 value	Interpretation	Usual pathway
<1.30	Low risk	Advanced fibrosis is less likely; follow-up depends on clinical risk.
1.30–2.67	Indeterminate	Consider second-line testing, such as elastography or ELF.
>2.67	High risk	Consider specialist assessment and further fibrosis evaluation.

Important limitations

For adults aged 65 years or older, a threshold around 2.0 is commonly used in the initial pathway to reduce false-positive classification from age.
Performance is limited in adults younger than 35 years.
Do not rely on FIB-4 during acute illness or when AST, ALT, or platelet count may be transiently affected.
FIB-4 estimates fibrosis risk; it does not diagnose fibrosis or directly calculate cardiovascular risk.

References

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):1317–1325. doi:10.1002/hep.21178

Rinella ME, Neuschwander-Tetri BA, Siddiqui MS, et al.AASLD Practice Guidance on the clinical assessment and management of nonalcoholic fatty liver disease. Hepatology. 2023;77(5):1797–1835. doi:10.1097/HEP.0000000000000323

European Association for the Study of the Liver, European Association for the Study of Diabetes, and European Association for the Study of Obesity.EASL–EASD–EASO Clinical Practice Guidelines on the management of metabolic dysfunction-associated steatotic liver disease (MASLD). Journal of Hepatology. 2024. Official guideline

Clinical disclaimer: This calculator is intended to support, not replace, clinical assessment. FIB-4 is a fibrosis risk-stratification tool and is not a direct cardiovascular risk calculator. Interpret results with the patient's age, clinical context, laboratory trends, comorbidities, and current local guidance. Confirmatory testing may be needed before making diagnostic or management decisions.