What APRI score indicates significant fibrosis?

An APRI score above 0.5 is the commonly cited threshold for predicting significant fibrosis (Metavir ≥F2) in hepatitis C. Scores below 0.5 make significant fibrosis unlikely, while scores above 1.0 suggest cirrhosis. These cutoffs are based on meta-analyses but have moderate sensitivity (~50–55%) and specificity (~80–85%).

What is the AST upper limit of normal (ULN)?

The ULN is the highest AST value considered normal by your specific laboratory. It varies by lab and patient sex — a common default is 40 U/L for adults, but your lab report or reference range should confirm this. Using the correct ULN is important for an accurate APRI calculation.

Is APRI valid for conditions other than hepatitis C?

APRI was originally validated in chronic hepatitis C. It has been studied in hepatitis B, NAFLD, and HIV/HCV co-infection, but its accuracy is lower in these populations. For NAFLD, FIB-4 index is often preferred. Always interpret APRI in the context of the specific clinical diagnosis.

Can APRI replace liver biopsy?

APRI is a non-invasive alternative, not a replacement. It is useful for ruling out significant fibrosis (low APRI) or suggesting cirrhosis (high APRI), but scores in the intermediate range (0.5–1.5) often remain indeterminate and may still require biopsy for definitive staging.

Why does platelet count affect the fibrosis score?

In liver fibrosis and cirrhosis, portal hypertension leads to splenomegaly, which sequesters platelets and reduces circulating platelet count. Elevated AST reflects hepatocyte injury. The combination of high AST and low platelets — captured by the APRI formula — correlates with advancing fibrosis.

APRI Score Calculator (Liver Fibrosis)

Name: APRI Score Calculator (Liver Fibrosis)
Availability: InStock
Author: Nham Vu

Enter AST, its upper limit of normal, and platelet count to compute APRI and get a fibrosis/cirrhosis risk interpretation.

Lab Values

AST (U/L)

Aspartate aminotransferase from serum chemistry panel

AST Upper Limit of Normal — ULN (U/L)

Lab-specific reference ceiling; commonly 40 U/L for adults

Platelet Count (10⁹/L)

Enter in 10⁹/L — e.g. type 120 for 120,000/µL

APRI Score & Interpretation

Enter lab values and click Calculate to see the APRI score.

Threshold Reference

< 0.5 — Significant fibrosis unlikely

0.5 – 1.0 — Possible significant fibrosis (≥F2); consider further workup

> 1.0 — Cirrhosis likely; liver biopsy or imaging indicated

For clinical decision support only. Not a substitute for clinical judgment or liver biopsy.

Summary

Enter AST, its upper limit of normal, and platelet count to compute APRI and get a fibrosis/cirrhosis risk interpretation.

How it works

Enter the serum AST value in U/L from the patient's lab report.
Confirm the AST upper limit of normal (ULN) for your laboratory — commonly 40 U/L.
Enter the platelet count in 10⁹/L (e.g., type 150 for 150 × 10⁹/L).
The tool computes: APRI = (AST / ULN_AST) / Platelet × 100.
Review the result: APRI < 0.5 makes significant fibrosis unlikely; > 0.5 suggests ≥F2; > 1.0 suggests cirrhosis.

Use cases

Initial screening for significant fibrosis in chronic hepatitis C patients before biopsy.
Monitoring disease progression over serial blood draws without repeat imaging.
Guiding decisions on liver biopsy necessity in resource-limited settings.
Assessing cirrhosis risk alongside FIB-4 index for a non-invasive fibrosis panel.
Teaching clinical scoring systems in hepatology and internal medicine education.
Pre-treatment assessment before initiating antiviral therapy for hepatitis C.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu