FIB-4 Calculator
Calculate FIB-4 and APRI scores to assess liver fibrosis and disease progression risk
Calculate FIB-4 and APRI Scores
Patient's age in years (most accurate for ages 35-65)
Aspartate transaminase level (normal: 10-40 U/L)
Alanine transaminase level (normal: 7-56 U/L)
Platelet count (normal: 150,000-400,000/μL)
FIB-4 Score Results
APRI Score Results
⚠️ Medical Disclaimer
This calculator is for educational purposes only and should not replace clinical judgment. FIB-4 and APRI scores are screening tools and may require additional testing for confirmation. Always consult with healthcare providers for proper interpretation and clinical decision-making.
Score Analysis
Example Calculation
Patient with NAFLD Screening
Age: 55 years
AST: 45 U/L
ALT: 38 U/L
Platelet Count: 180,000/μL
Calculations
FIB-4: (55 × 45) / (180,000 × √38) = 2475 / (180,000 × 6.16) = 2.23
APRI: (45/40) / (180) = 1.125 / 180 = 0.63
Interpretation: Intermediate risk for advanced fibrosis - consider additional testing
FIB-4 Reference Ranges
Low Risk (< 1.45)
Excludes advanced fibrosis in 94.7% of patients
Intermediate (1.45-3.25)
Consider additional testing
High Risk (> 3.25)
Confirms advanced fibrosis in 82.1% of patients
APRI Reference Ranges
Low Risk (< 0.5)
Rules out progression in ~87% of cases
Intermediate (0.5-1.0)
Intermediate risk of progression
High Risk (>= 1.0)
High possibility of severe cirrhosis
Normal Lab Values
Understanding FIB-4 and APRI Scores
What is FIB-4?
FIB-4 (Fibrosis-4) is a non-invasive scoring system used to assess the probability of liver fibrosis, particularly in patients with NAFLD (Non-Alcoholic Fatty Liver Disease), hepatitis C, B, or HIV co-infections.
Clinical Applications
- •Screen for advanced liver fibrosis
- •Monitor NAFLD progression
- •Guide referral decisions
- •Reduce need for liver biopsy
Formula Components
FIB-4 = (age × AST) / (platelets × √ALT)
APRI = (AST/40) / (platelets×10⁻⁹)
- Age: Patient's age in years
- AST: Aspartate transaminase (U/L)
- ALT: Alanine transaminase (U/L)
- Platelets: Platelet count (/μL)
Best Performance: FIB-4 is most accurate in patients aged 35-65 years. Results may be less reliable outside this age range.
NAFLD and Liver Fibrosis
Non-Alcoholic Fatty Liver Disease (NAFLD) is the most common liver disease worldwide. It can progress to advanced fibrosis and cirrhosis, leading to permanent liver function loss.
Risk Factors for NAFLD
- • Obesity and overweight
- • Type 2 diabetes
- • Metabolic syndrome
- • Hypertension
- • Dyslipidemia
- • Insulin resistance
When to Use FIB-4
- • Suspected NAFLD patients
- • Elevated liver enzymes
- • Metabolic risk factors
- • Hepatitis C screening
- • Pre-treatment assessment
- • Regular monitoring