🧬 AST to Platelet Ratio Index (APRI)
Enter liver and cell parameters to calculate liver scarring ratio.
What the APRI score is
APRI (AST to Platelet Ratio Index) is a simple blood-test score that estimates liver scarring (fibrosis). It was published by Wai and colleagues in 2003 for people with chronic hepatitis C, and the World Health Organization recommends it for hepatitis B and C in places where scans such as FibroScan are not available.
APRI = (AST ÷ AST upper limit of normal) ÷ platelets (109/L) × 100
What you need
- AST in U/L from your blood test.
- AST upper limit of normal: the top of the reference range printed next to your AST result. It differs between labs; 40 U/L is a common value.
- Platelet count in 109/L. This is the same number as 103/µL (for example 180).
How the result is read
- Below 0.5: significant fibrosis is unlikely.
- 0.5 to 1.5: indeterminate; another test is needed to decide.
- 1.5 or higher: significant fibrosis is likely.
- 2.0 or higher: the WHO cut-off suggesting cirrhosis in chronic hepatitis B and C. A score below 1.0 makes cirrhosis unlikely.
Limits
- APRI is good at ruling out advanced disease but misses some cases, so a low score does not replace follow-up if you have chronic liver disease.
- Anything that raises AST (recent alcohol, muscle injury, hard exercise) or lowers platelets for other reasons can distort the score.
- For fatty liver disease, doctors usually prefer the FIB-4 index.
Educational estimate only. Please discuss your result with your doctor.