NAFLD Fibrosis Score Calculator

NAFLD Fibrosis Score Calculator for Gastroenterology. The original historical cutoffs are strictly below -1.455 and above 0.676. Values exactly at either limit remain indeterminate. A result above the upper limit supports further fibrosis assessment, not a confirmed fibrosis stage.

For shared guidance on choosing a tool and documenting results, read the clinical calculator workflow.

How this calculator works

NFS = -1.675 + 0.037 x age + 0.094 x BMI + 1.13 x impaired-glucose/diabetes indicator + 0.99 x AST/ALT - 0.013 x platelets - 0.66 x albumin in g/dL. Historical decision limits are -1.455 and 0.676.

When to use this calculator

This is a historical noninvasive advanced-fibrosis model developed in NAFLD. Use only with population and pathway context; it is less reliable in obesity and type 2 diabetes and is not a substitute for sequential assessment.

Inputs used

  • Age (completed years)
  • BMI (kg/m2)
  • Impaired fasting glucose or diabetes
  • AST (U/L)
  • ALT (U/L)
  • Platelets (10^9/L)
  • Albumin (g/dL)

Clinical interpretation

The original historical cutoffs are strictly below -1.455 and above 0.676. Values exactly at either limit remain indeterminate. A result above the upper limit supports further fibrosis assessment, not a confirmed fibrosis stage.

Worked example

Fictional teaching case. Age (completed years): 58; BMI (kg/m2): 33; Impaired fasting glucose or diabetes: Yes; AST (U/L): 45; ALT (U/L): 30; Platelets (10^9/L): 180; Albumin (g/dL): 4. Result: 1.208. Above historical upper cutoff. Use an etiology- and population-appropriate sequential assessment. Acute illness and nonhepatic changes in platelets or enzymes can mislead; no score confirms or excludes fibrosis by itself.

Limitations and safety notes

The original name is retained for model identity. Accuracy is reduced in younger adults, obesity and diabetes; predictive values are not universal. Use an etiology- and population-appropriate sequential assessment. Acute illness and nonhepatic changes in platelets or enzymes can mislead; no score confirms or excludes fibrosis by itself.

Frequently asked questions

Does the original name mean the score diagnoses the cause of steatosis?

No. It estimates fibrosis risk in its studied setting and does not establish the cause of liver disease.

What can change the meaning of this result?

The original name is retained for model identity. Accuracy is reduced in younger adults, obesity and diabetes; predictive values are not universal. Use an etiology- and population-appropriate sequential assessment. Acute illness and nonhepatic changes in platelets or enzymes can mislead; no score confirms or excludes fibrosis by itself.

References

  • Original six-variable NFS derivation and cutoff study. https://pubmed.ncbi.nlm.nih.gov/17393509/
  • AASLD 2023 Figure 2: FIB-4 age/population restrictions and sequential assessment; relevant full text accessed, not drug guidance. https://pmc.ncbi.nlm.nih.gov/articles/PMC10735173/

Editorial review and citation methodology

Maintained by the Quick Medical Calculator Editorial Team. Content record date: September 9, 2026. A content date is not evidence of independent clinical review. Individual clinical sign-off is not recorded on this page.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

Related reviewed calculators