Fibrotic NASH Index (FNI)
FNI (Fibrotic NASH Index) is a screening index for fibrotic non-alcoholic steatohepatitis (NASH) in people at high metabolic risk: those with type 2 diabetes, excess weight, obesity or metabolic syndrome. It is calculated from just three blood tests and gives the probability as a percentage right away.
What FNI is and why it matters
FNI (Fibrotic NASH Index) is a calculated index for screening for fibrotic NASH in patients at high risk of metabolic dysfunction: with type 2 diabetes mellitus, excess weight (BMI ≥ 25), obesity (BMI ≥ 30) and metabolic syndrome. It requires no equipment — only three routine blood tests are needed.
Non-alcoholic steatohepatitis (NASH) is an inflammatory, infiltrative process in the parenchyma and stroma of the liver with foci of fibrosis. It is a more “active” and dangerous form of NAFLD than simple steatosis: it is the combination of inflammation and fibrosis that determines the prognosis.
What's needed for the calculation
FNI is calculated from three values taken from routine blood tests:
- AST, U/L. A liver enzyme; it rises with inflammation and damage to liver cells.
- Glycated hemoglobin HbA1c, %. It reflects the average blood sugar level over the past ~3 months — a marker of the metabolic background.
- HDL cholesterol, mmol/L. The “good” cholesterol; it falls with metabolic dysfunction. The calculator will convert it to the required units itself.
How to take the tests
AST and HDL are part of a standard blood chemistry panel (HDL is in the lipid profile), while HbA1c is a separate test that does not require strict fasting. The day before, avoid intense workouts and alcohol — they temporarily raise AST and will distort the result.
FNI Calculator
Enter AST, glycated hemoglobin HbA1c and HDL — the calculator will compute the Fibrotic NASH Index (FNI), convert it into a probability and tell you whether fibrotic NASH can be ruled out. The calculation runs on the server.
Threshold: FNI ≤ 0.10 (10%) — fibrotic NASH can be ruled out; > 0.10 — cannot be ruled out.
How to read the result
FNI is a probability from 0 to 1 (we show it as a percentage). The scale has a single threshold:
| FNI | Interpretation |
|---|---|
| ≤ 0.10 (≤ 10%) | Fibrotic NASH can be ruled out |
| > 0.10 (> 10%) | Fibrotic NASH cannot be ruled out |
A low probability of fibrotic NASH. Monitoring and work on metabolic risk factors.
An elevated probability: further work-up is indicated — elastography and a physician consultation.
Why these particular values
FNI combines three markers of different aspects of the disease: AST reflects damage and inflammation in the liver, HbA1c reflects the metabolic background and impaired carbohydrate metabolism, and a lowered HDL is a characteristic sign of metabolic dysfunction. Together they clearly separate people for whom fibrotic NASH is unlikely from those who need deeper diagnostics.
Its place in the section and other indices
FNI answers a narrow question: is active fibrotic NASH likely. It is convenient to combine it with other scores: FIB-4 and NFS assess the stage of fibrosis, LSS assesses tissue stiffness, and the steatosis indices assess the presence of fat. The conclusion is always interpreted by a physician.
Limitations and important caveats
- It is not a diagnosis. FNI estimates the probability of fibrotic NASH; it is confirmed by elastography, ELF or biopsy.
- It is screening for a risk group. The index was developed for people with metabolic dysfunction; outside this group, interpret it with caution.
- It depends on test quality. Errors in AST, HbA1c or HDL shift the result.
- “Cannot be ruled out” is not a verdict. It is a signal for further work-up, not confirmation of disease.
- It does not replace an examination. The result is interpreted by a physician, taking your history and comorbidities into account.
Frequently asked questions
How does NASH differ from ordinary fatty liver disease?
NAFLD is primarily the accumulation of fat (steatosis). NASH is a more active form in which inflammation and foci of fibrosis are added to the fat. It is NASH that is more dangerous in terms of progression.
In what units should I enter HDL?
In mmol/L, as on the lipid profile report. The calculator will convert the value into mg/dL, which the formula uses.
Who is FNI suitable for?
Above all, people at metabolic risk: type 2 diabetes, excess weight or obesity, metabolic syndrome. It is on this group that the index has been validated.
What should I do if the result is above 0.10?
This is not a diagnosis but a reason not to delay a visit to a physician and to discuss elastography (FibroScan/VCTE) or other methods of assessing fibrosis.
