APRI needs only two routine blood tests, which makes it useful where elastography is not available. It is best at ruling fibrosis in or out at the extremes.
How to use the APRI Calculator
- AST
- AST upper limit of normal
- Platelets
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter AST, the lab’s upper limit of normal and platelets.
Inputs explained
| Field | What to enter |
|---|---|
| AST | In U/L |
| AST upper limit of normal | In U/L |
| Platelets | In ×10⁹/L |
Example values
How the main result changes when AST changes and everything else stays at the example values above:
| AST (U/L) | APRI |
|---|---|
| 40 | 0.67 |
| 60 | 1 |
| 80 | 1.33 |
| 100 | 1.67 |
| 120 | 2 |
| 160 | 2.67 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
APRI = (AST ÷ AST upper limit of normal) ÷ platelets (×10⁹/L) × 100
< 0.5 significant fibrosis unlikely · > 1.5 significant fibrosis likely · > 2.0 cirrhosis likely (WHO)
Worked example
Inputs — AST: 80 U/L; AST upper limit of normal: 40 U/L; Platelets: 150 ×10⁹/L.
Results — APRI = 1.33; Interpretation = Indeterminate.
Key terms
- APRI
- AST-to-platelet ratio index.
Frequently asked questions
What APRI suggests cirrhosis?
Above 2.0 (WHO hepatitis guidelines).
How accurate is APRI?
Moderately – best for ruling out cirrhosis at low values.
Can APRI be used in fatty liver disease?
FIB-4 or NAFLD fibrosis score are preferred there.