Metabolic hepatology
NAFLD Fibrosis Score (NFS)
The NAFLD fibrosis score differentiates mild from advanced fibrosis in MASLD/NAFLD using readily available clinical data. Enter demographic, metabolic, and laboratory parameters to stratify risk.
Inputs summary
- Age: 52 yrs
- BMI: 32.0 kg/m²
- AST/ALT ratio: 1.14
NAFLD fibrosis score
0.280
Cut-offs: -1.455 and 0.675
NFS between -1.455 and 0.675 is inconclusive. Combine with FIB-4, ELF, or FibroScan® to clarify fibrosis stage.
Combine with FIB-4 or transient elastography per AASLD/EASL guidelines for MASLD fibrosis assessment.
How to Use This Calculator
Collect metabolic and laboratory data
Include BMI, fasting glucose or diabetes status, liver enzymes, platelets, and albumin from a recent evaluation.
Enter values carefully
Ensure ALT is non-zero (values less than 1 should be set to 1 for practical purposes). Confirm platelet unit is ×10⁹/L.
Interpret with other fibrosis tools
Low scores can avoid unnecessary imaging. Indeterminate/high scores should prompt elastography, ELF, or liver biopsy.
Formula
NAFLD fibrosis score = -1.675 + 0.037 × Age (years) + 0.094 × BMI (kg/m²) + 1.13 × IFG/diabetes (1/0) + 0.99 × AST/ALT ratio − 0.013 × Platelet count (×10⁹/L) − 0.66 × Albumin (g/dL)
Interpretation: <-1.455 (rule out advanced fibrosis); -1.455 to 0.675 (indeterminate); >0.675 (advanced fibrosis likely).
Full Description
The NAFLD fibrosis score is a validated non-invasive tool derived from large cohorts to stratify fibrosis in non-alcoholic fatty liver disease. It leverages metabolic risk factors and simple laboratory markers to triage patients who need elastography or biopsy.
Strengths include accessibility and high negative predictive value. However, accuracy declines in younger patients, morbid obesity, or other causes of thrombocytopenia/hypoalbuminemia. Use in conjunction with FIB-4, imaging, and clinical judgement.
Frequently Asked Questions
What qualifies as impaired fasting glucose?
Fasting plasma glucose 100–125 mg/dL, HbA1c 5.7–6.4%, or known diabetes should be marked as “Yes.”
Should I adjust for platelet units?
Enter platelets in ×10⁹/L (same as K/µL). Convert from other units before using the score.
Is the score valid after bariatric surgery?
Weight loss can improve labs and lower NFS. Recalculate after significant weight changes to reassess fibrosis risk.
Can I use NFS in viral hepatitis?
NFS was designed for MASLD/NAFLD. Use alternative fibrosis scores for viral or cholestatic liver disease.