FIB-4 Liver Fibrosis Index
This index screens for fibrosis without a biopsy, using ordinary blood results. A low value largely rules out advanced fibrosis, which makes it a first-line filter for deciding who needs further testing.
Your numbers
FIB-4
1.24
Total : HDL
0.81
Platelets (10⁹/L)
220
What it means
1.24 is in the low band (under 1.3); advanced fibrosis is unlikely.
Formula
FIB-4 = Age × AST ÷ (Platelets (10⁹/L) × √ALT)
Above 65 the lower cut-off rises to 2.0. Acute hepatitis or recent heavy drinking spikes the enzymes and distorts the result.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| AgeAge in completed years — it shifts by one depending on the birthday. | 52 | 18 ~ 100 |
| ASTAn enzyme in liver and muscle; it leaks into blood when cells are damaged. | 34 | 5 ~ 500 |
| ALTAn enzyme mostly in the liver — more liver-specific than AST. | 42 | 5 ~ 500 |
| Platelets (10⁹/L)The clotting cells; the count falls as the liver stiffens. | 220 | 20 ~ 600 |
Step by step
Quick reference table
Results when only Age changes and everything else stays put.
| Age | FIB-4 | Total : HDL | Platelets (10⁹/L) |
|---|---|---|---|
| 26 | 0.62 | 0.81 | 220 |
| 39 | 0.93 | 0.81 | 220 |
| 52 | 1.24 | 0.81 | 220 |
| 78 | 1.86 | 0.81 | 220 |
| 100 | 2.38 | 0.81 | 220 |
What each result means
| Result | At default values |
|---|---|
| FIB-4A fibrosis screen; low values largely rule out advanced disease. | 1.24 |
| Total : HDLTotal cholesterol over HDL — lower is better. | 0.81 |
| Platelets (10⁹/L)The clotting cells; the count falls as the liver stiffens. | 220 |
Common mistakes
Above 65 the lower cut-off rises to 2.0. Acute hepatitis or recent heavy drinking spikes the enzymes and distorts the result.
Glossary
- Age
- Age in completed years — it shifts by one depending on the birthday.
- AST
- An enzyme in liver and muscle; it leaks into blood when cells are damaged.
- ALT
- An enzyme mostly in the liver — more liver-specific than AST.
- Platelets (10⁹/L)
- The clotting cells; the count falls as the liver stiffens.
- FIB-4
- A fibrosis screen; low values largely rule out advanced disease.
- Total : HDL
- Total cholesterol over HDL — lower is better.
Frequently asked questions
Q. How is FIB-4 Liver Fibrosis Index calculated?
FIB-4 = Age × AST ÷ (Platelets (10⁹/L) × √ALT) — This index screens for fibrosis without a biopsy, using ordinary blood results. A low value largely rules out advanced fibrosis, which makes it a first-line filter for deciding who needs further testing.
Q. Can you walk through an example?
With Age 52, AST 34, ALT 42, Platelets (10⁹/L) 220, the answer is FIB-4 1.24.
Q. What do I need to enter?
Enter Age, AST, ALT, Platelets (10⁹/L). The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Age moves the answer to Age 26 → FIB-4 0.62 and Age 100 → FIB-4 2.38. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
Above 65 the lower cut-off rises to 2.0. Acute hepatitis or recent heavy drinking spikes the enzymes and distorts the result.
Related calculators
These calculators help you understand health figures; they do not replace diagnosis or prescription. See a clinician if you have symptoms.