APRI Score Calculator

Calculate the AST-to-Platelet Ratio Index (APRI) for liver fibrosis staging.

Aug 31, 2026 Clinical Chemistry #liver #apri #fibrosis #noninvasive

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All fields required unless noted

AST (U/L)

Platelet count (10⁹/L)

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Formula & Clinical Notes

Formula

APRI = (AST/40) ÷ Platelet × 100

Clinical Notes

APRI = (AST / upper limit of normal) / platelet count × 100, using an AST ULN of 40 U/L and platelet count in 10⁹/L. APRI < 0.5 makes significant fibrosis unlikely; APRI ≥ 1.0 suggests cirrhosis and ≥ 1.5 strongly suggests cirrhosis. The score is validated for chronic hepatitis C and is also used in hepatitis B and fatty liver disease.

Sources

Wai et al. (2003) — A simple noninvasive index to predict fibrosis (APRI)