FibroTest
FibroTest is a panel of calculated tests that uses five blood biomarkers to assess the severity of liver fibrosis and translates the result into stages of morphological change on the METAVIR, Knodell and Ishak systems. In essence, it is a non-invasive alternative to biopsy for a first-line assessment of liver scarring.
What FibroTest is and why it matters
To assess how much the liver has scarred, a biopsy is classically needed. FibroTest solves the same task non-invasively: from five blood values, age and sex it calculates an index from 0 to 1 and translates it into a fibrosis stage. It is a convenient tool for a first-line assessment and for tracking change over time, especially when a biopsy is undesirable or unavailable.
Liver fibrosis and its stages
Liver fibrosis is the gradual replacement of healthy liver tissue by connective tissue, which disrupts the organ's structure and function. Its end stage is cirrhosis. To speak the same language, pathologists use point-based staging systems; FibroTest translates its index into three of them at once — METAVIR, Knodell and Ishak.
What's needed for the calculation
Besides age and sex, five blood values are needed:
- Total bilirubin, µmol/L. A pigment the liver neutralizes; it rises when the liver's function is impaired.
- Haptoglobin, g/L. A plasma protein; its level changes with fibrosis, which makes it informative for the index.
- α2-macroglobulin, g/L. A protein that reflects fibrogenesis activity; it rises as scarring progresses.
- Gamma-glutamyl transferase (GGT), U/L. A liver enzyme sensitive to injury and stasis.
- Apolipoprotein A1, g/L. The protein of “good” cholesterol; it usually falls with fibrosis.
These values are combined into a single index using a validated model. The calculator below performs the correct calculation with translation into stages — this spares you manual-calculation errors and keeps the result aligned with the original model.
How to take the tests
All five biomarkers are blood tests; some are part of a blood chemistry panel, others (haptoglobin, α2-macroglobulin, ApoA1) are ordered separately. They are usually drawn in a single sample on an empty stomach.
Preparation
Take them on an empty stomach (8–12 hours without food); the day before, avoid alcohol and heavy fatty meals. Take the values and units strictly from your own report — they matter for a correct index.
FibroTest Calculator
Enter your sex, age and five blood biomarkers — the calculator will compute the FibroTest index, translate it into METAVIR/Knodell/Ishak stages and explain the result. The calculation runs on the server.
The FibroTest scale runs 0–1: ≥0.59 — significant fibrosis (METAVIR F3), ≥0.75 — cirrhosis (METAVIR F4).
How to read the result
The FibroTest index is a number from 0 to 1. Each range corresponds to a fibrosis stage in three staging systems at once.
| FibroTest | METAVIR | Knodell | Ishak |
|---|---|---|---|
| 0.00–0.21 | F0 | F0 | F0 |
| 0.22–0.27 | F0–F1 | F0–F1 | F1 |
| 0.28–0.31 | F1 | F1 | F2 |
| 0.32–0.48 | F1–F2 | F1–F3 | F2–F3 |
| 0.49–0.58 | F2 | F1–F3 | — |
| 0.59–0.72 | F3 | F3 | F4 |
| 0.73–0.74 | F3–F4 | F3–F4 | F5 |
| 0.75–1.00 | F4 | F4 | F6 |
METAVIR F0–F1. No significant scarring; monitoring and control of risk factors.
METAVIR F1–F2. The stage should be clarified with elastography.
METAVIR F3. A specialist consultation and imaging confirmation.
METAVIR F4. Confirmation, assessment of complications and cancer risks are essential.
Three staging systems
Fibrosis is described with different scales; FibroTest provides a translation into all three so that the result is clear to any physician.
METAVIR (Bedossa, Poynard, 1996)
F0 — no fibrosis, F1 — portal fibrosis without septa, F2 — portal fibrosis with occasional septa, F3 — numerous septa without cirrhosis, F4 — liver cirrhosis.
Knodell index (1981)
F0 — no fibrosis, F1 — fibrous expansion of portal tracts, F2 — expansion with porto-portal septa, F3 — bridging fibrosis (porto-portal or porto-central septa), F4 — cirrhosis.
Ishak scale (1995)
A modified Knodell score with a finer gradation: F0 — no fibrosis, F1–F2 — fibrous expansion of portal tracts, F3–F4 — occasional and marked bridging septa, F5 — marked bridging fibrosis with nodules (incomplete cirrhosis), F6 — cirrhosis.
When FibroTest is unreliable
- Cholestasis (bile stasis). It sharply changes bilirubin and GGT — the index becomes unreliable.
- Hemolysis (breakdown of red blood cells). It distorts haptoglobin and bilirubin, over- or underestimating the result.
- Acute inflammation. Haptoglobin and α2-macroglobulin are acute-phase proteins, so interpretation is unreliable during infection or a flare.
- Borderline values. Results near the range boundaries should be interpreted together with a physician and other methods.
Its place in the section and other indices
FibroTest and FIB-4 solve the same task — assessing fibrosis — but in different ways: FIB-4 is calculated from four routine values and is free in any lab, while FibroTest is more accurate thanks to specific proteins (haptoglobin, α2-macroglobulin, ApoA1). The steatosis indices — FLI, HSI, NAFLD-LFS — answer an earlier question: is there fat in the liver. Together they describe the “steatosis → fibrosis” path, and the conclusion is interpreted by a physician.
Limitations and important caveats
- It is not a diagnosis. FibroTest estimates the likely stage, which is confirmed by elastography or biopsy.
- It is sensitive to comorbid conditions. Cholestasis, hemolysis and acute inflammation distort the result.
- It depends on test quality. Errors in any of the five biomarkers shift the index.
- It does not replace an examination. The result is interpreted by a physician, taking your history and other data into account.
Frequently asked questions
How does FibroTest differ from FIB-4?
Both assess fibrosis, but FIB-4 uses routine ALT, AST, platelets and age, while FibroTest uses specific proteins (haptoglobin, α2-macroglobulin, ApoA1) and is therefore considered more accurate. On the other hand, the tests for FibroTest are more expensive and are not available in every lab.
Where can I get all five biomarkers?
Bilirubin and GGT are part of a routine blood chemistry panel; haptoglobin, α2-macroglobulin and ApoA1 are ordered separately. Many labs offer a ready-made panel for FibroTest.
Why might the result be unreliable?
In cholestasis and hemolysis, the biomarkers in the formula (bilirubin, haptoglobin) change for reasons unrelated to fibrosis, so the index is distorted. In these cases other methods are used.
Does a high FibroTest definitely mean cirrhosis?
No. A result ≥0.75 corresponds to METAVIR F4 and raises the likelihood of cirrhosis, but it requires confirmation by elastography or biopsy. The diagnosis is made by a physician.
What should I do with the result?
Show it to your physician along with your test results. For a low index — monitoring and work on risk factors; for a significant or high one — elastography/biopsy and a further work-up plan.
