Home › Hepatology & GI › APRI

APRI (AST to Platelet Ratio Index)

APRI = (AST ÷ AST upper limit of normal) ÷ platelets (10⁹/L) × 100. In hepatitis C, APRI ≤0.5 makes significant fibrosis unlikely, >1.5 makes it likely, and >2.0 suggests cirrhosis (WHO); ≤1.0 largely excludes cirrhosis.

AST (U/L)
Platelet count (×10⁹/L or ×10³/µL)
AST upper limit of normal (U/L)

—

Interpretation

Result	Meaning
≤ 0.5	Significant fibrosis unlikely
0.5–1.5	Indeterminate
> 1.5	Significant fibrosis likely
≤ 1.0	Cirrhosis unlikely
> 2.0	Cirrhosis likely

Formula

APRI = [AST (U/L) ÷ AST ULN (U/L)] ÷ platelets (10⁹/L) × 100

Clinical pearls

Use your laboratory's AST upper limit of normal; 40 U/L is assumed if not entered.
Derived in chronic hepatitis C; less accurate in MASLD and alcohol-related disease, where FIB-4 is preferred.

Examples

apri ast 80 plt 150 APRI with AST 120, platelets 90, upper limit of normal 35 ast to platelet ratio ast 35 plt 250

FAQ

What APRI indicates cirrhosis?

An APRI above 2.0 suggests cirrhosis (WHO hepatitis guidance); ≤1.0 makes cirrhosis unlikely.

What ULN should I use for AST?

Your laboratory's reference upper limit; many labs use about 35–40 U/L.

Evidence

Wai CT et al. A simple noninvasive index can predict both significant fibrosis and cirrhosis in patients with chronic hepatitis C. Hepatology 2003;38:518–26.

Hepatology & GI · Reviewed 2026-10-14 · Methodology