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FIB-4 Score Calculator & Interpretation

Calculate your FIB-4 score to assess the risk of advanced liver fibrosis. Based on AASLD/IDSA guidelines.

Calculate Your FIB-4 Score

What You Need: Your age, recent AST and ALT lab values (in U/L), and platelet count (in 10^9/L).

What is FIB-4?

FIB-4 is a simple, non-invasive test that uses routine blood work to estimate the risk of advanced liver fibrosis (scarring).

Formula: (Age × AST) / (Platelet count × √ALT)

Cutoff Values

Low Risk

< 1.30

Intermediate

1.30 - 2.67

High Risk

> 2.67

Understanding FIB-4 in Simple Terms

What Do These Lab Values Mean?

AST (Aspartate Aminotransferase)

An enzyme released when liver cells are damaged. Higher values suggest more liver inflammation.

ALT (Alanine Aminotransferase)

Another liver enzyme. ALT is more specific to liver injury than AST.

Platelets

Blood cells that help with clotting. Lower platelet counts can indicate advanced fibrosis.

What is Liver Fibrosis?

Fibrosis is scarring of the liver. When liver cells are damaged repeatedly (from fatty liver disease, alcohol, hepatitis, etc.), the body tries to repair them by creating scar tissue.

Stages: F0 (no scarring) → F1 (mild) → F2 (moderate) → F3 (advanced) → F4 (cirrhosis)

FIB-4 helps identify if you might have F3-F4 (advanced fibrosis) that needs urgent attention.

Important Notes:

  • ✓ FIB-4 is a screening tool, not a diagnosis
  • ✓ It cannot replace liver biopsy or FibroScan
  • ✓ Results may be affected by acute hepatitis or hemolysis
  • ✓ Always discuss results with your doctor
  • ✓ Intermediate results need further testing (FibroScan)

Clinical Guidelines & References

AASLD/IDSA Guidelines (2020)

The American Association for the Study of Liver Diseases and Infectious Diseases Society of America recommend FIB-4 as a first-line non-invasive test for fibrosis assessment in NAFLD.

Reference: Chalasani N, et al. The diagnosis and management of nonalcoholic fatty liver disease: Practice guidance from the American Association for the Study of Liver Diseases. Hepatology. 2018;67(1):328-357.

EASL Guidelines (2016)

European Association for the Study of the Liver recommends FIB-4 as a non-invasive marker for identifying patients at risk of advanced fibrosis.

Reference: European Association for the Study of the Liver. EASL Clinical Practice Guidelines: Management of hepatic encephalopathy. J Hepatol. 2014;60(3):715-735.

Shah et al. Validation Study (2009)

Original validation study showing FIB-4's accuracy in predicting advanced fibrosis in NAFLD patients.

Reference: Shah AG, et al. Comparison of noninvasive markers of fibrosis in patients with nonalcoholic fatty liver disease. Clin Gastroenterol Hepatol. 2009;7(10):1104-1112.

Disclaimer: This calculator is for educational purposes only. It is not a substitute for professional medical advice. Always consult with your healthcare provider to interpret your results and determine the appropriate next steps for your care.