Healthcare & Clinical
FIB-4 Index & APRI Score for Noninvasive Liver Fibrosis Staging
Calculate the hepatology FIB-4 Index = (Age * AST) / (Platelets * SQRT(ALT)) and AST-to-Platelet Ratio Index APRI = ((AST / AST_ULN) / Platelets) * 100 from routine CBC and liver panel labs.
Screen MASLD/NAFLD and viral hepatitis patients for advanced fibrosis!
Routine outpatient liver care uses two validated, zero-cost blood scores to rule out advanced hepatic fibrosis (F3–F4 bridging fibrosis/cirrhosis) before ordering FibroScan elastography or biopsy! Richard Sterling's Fibrosis-4 Index combines patient Age (years), AST (U/L), Platelets (10^9/L, e.g., 130 for 130,000/uL), and ALT (U/L): FIB-4 = (Age * AST) / (Platelets * SQRT(ALT))!
In MASLD/NAFLD and chronic hepatitis guidelines, FIB-4 < 1.30 rules out advanced fibrosis with >90% negative predictive value, 1.30–2.67 is indeterminate (refer for elastography), and FIB-4 > 2.67 signals high risk of advanced fibrosis! Complementing FIB-4 without age dependence, Wai's AST-to-Platelet Ratio Index evaluates APRI = ((AST / AST_ULN) / Platelets) * 100 (< 0.50 low risk; > 1.50 high probability of significant fibrosis)!
| Clinical Liver Profile (AST ULN = 40 U/L) | Age / AST / ALT / Platelets | FIB-4 Score & Risk Tier | APRI Score |
|---|---|---|---|
| Low-Risk Primary Care Screen | 38 yr | AST 26 | ALT 36 | Plt 250 | 0.66 (< 1.30 Low Risk) | 0.26 (< 0.50) |
| Indeterminate MASLD Follow-Up | 52 yr | AST 48 | ALT 55 | Plt 190 | 1.77 (1.30 - 2.67 Elastography) | 0.63 |
| Advanced Fibrosis / Cirrhosis | 58 yr | AST 84 | ALT 64 | Plt 130 | 4.68 (> 2.67 High Risk F3-F4!) | 1.62 (> 1.50!) |
FIB-4 Noninvasive Liver Fibrosis Index Formula
Evaluates (Age * AST) / (Platelets_10e9L * SQRT(ALT)) after verifying positive lab values (enter platelets as 10^9/L, e.g., 130—NOT 130,000).
=IF(OR(B2 <= 0, B3 <= 0, B4 <= 0, B5 <= 0), "Invalid Lab Input", ROUND((B2 * B3) / (B5 * SQRT(B4)), 2))AST-to-Platelet Ratio Index APRI = ((AST / AST_ULN) / Platelets) * 100
Divides AST ratio (B3 / B6) by platelet count B5 (10^9/L) and multiplies by 100.
=IF(OR(B5 <= 0, B6 <= 0), "Invalid Platelets or ULN", ROUND(((B3 / B6) / B5) * 100, 2))Try the example
Use the original values or change them to test your understanding.