This calculator is for general information and education. It is not medical advice and does not replace the judgment of a doctor, nurse or pharmacist who knows the full clinical picture.
Fatty liver disease, now called MASLD (metabolic dysfunction-associated steatotic liver disease, formerly NAFLD), affects about one adult in three in the United States. Most people with it never develop serious liver damage. What predicts the future is fibrosis, the scarring that can progress to cirrhosis. The NAFLD fibrosis score (NFS), published by Angulo and colleagues in 2007, uses routine data to sort patients into low, indeterminate and high risk of advanced fibrosis.
The formula
NFS = −1.675 + 0.037 × age + 0.094 × BMI + 1.13 × (impaired fasting glucose or diabetes) + 0.99 × AST/ALT − 0.013 × platelets − 0.66 × albumin
Age is in years, BMI in kg/m², platelets in thousands per µL (×10⁹/L), albumin in g/dL, and the diabetes term is 1 if fasting glucose is impaired or diabetes is present, 0 otherwise.
Example
A 55-year-old with a BMI of 30, type 2 diabetes, AST 35 U/L, ALT 40 U/L, platelets 220 and albumin 4.2 g/dL scores −0.456, in the indeterminate zone.
Interpretation
| NFS | Meaning |
|---|---|
| below −1.455 | advanced fibrosis unlikely (negative predictive value about 90%) |
| −1.455 to 0.676 | indeterminate |
| above 0.676 | advanced fibrosis (F3 to F4) likely |
In adults aged 65 or more, a lower-risk threshold of 0.12 has been proposed instead of −1.455, because age alone pushes the score up.
What happens next
US and European guidelines recommend a two-step approach. A simple blood score, usually FIB-4, comes first. If it is not clearly low, the next step is vibration-controlled transient elastography (FibroScan) or a specialized blood test such as ELF. People with a high score are referred to a liver specialist.
Limits
- The NFS was built in people with fatty liver; it is not designed for alcohol-related or viral liver disease.
- A large share of patients land in the indeterminate zone, which is why a second test is so often needed.
- Low albumin or low platelets from other causes (kidney disease, bleeding, medicines) can push the score up.
Weight loss of 7 to 10%, regular exercise and good control of diabetes are the treatments with the best evidence for reducing liver fat and, in some patients, fibrosis.