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🫀 NAFLD Activity Score (NAS)

UseWhen to use: reading or documenting NAFLD/NASH biopsy activity in clinical/research contexts.

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StrataHigher NAS reflects more activity; NASH remains a pattern diagnosis, not NAS cut-off alone.

LimitsWhen not to use: as a substitute for NAFLD Fibrosis Score or elastogr… · Pitfall: equating NAS ≥5 with automatic NASH without histology patter… · Requires adequate biopsy sampling.

SourceAASLD NAFLD guidance; 《非酒精性脂肪性肝病防治指南》 on zh

Runs locally in your browser (no PHI uploaded). For licensed clinicians — not a substitute for clinical judgement.
Stored on this device for revisit reminders

This-shift next steps

After scoring: open the scene pack, peer scores, and the matching pathway. Local reference — no HIS write.

Scene next step
📋liverOpen scene pack →
Related scores
Matching pathway
🧭cholangitisOpen pathway →
Score + version; reference only — not a substitute for care · no HIS write

Paste the link in Slack, Teams, X, or LinkedIn — the preview image comes from this page’s Open Graph card.

Methodology · worked example, guidelines & full notes
Clinical takeaway

Activity ≠ fibrosis.

When to use

When to use: reading or documenting NAFLD/NASH biopsy activity in clinical/research contexts.

How it works

Steatosis 0–3 + lobular inflammation 0–3 + ballooning 0–2 = NAS 0–8.

Key points

  • Activity ≠ fibrosis.
  • Separate from nafld_fibrosis (NFS).
  • Next: fibrosis stage; metabolic risk pathway.

References

Worked calculation

The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.

Steatosis grade1 — 5–33%
Lobular inflammation1 — <2 foci/20× field
Hepatocyte ballooning1 — few

→NAS3/8

  • Components：S1 + I1 + B1
  • Band：Borderline / indeterminate range — pattern matters
Steatosis grade0 — <5%
Lobular inflammation0 — none
Hepatocyte ballooning0 — none

→NAS0/8

  • Components：S0 + I0 + B0
  • Band：Often not diagnostic of NASH alone (low NAS)
Verification & sources · governance
FAQ

Frequently asked questions

Does NAFLD Activity Score (NAS) upload patient data? Where is it calculated?
Calculation runs locally in the browser; inputs and results are not uploaded. For licensed clinicians only; interpret with history, investigations and local protocols — not a diagnosis or prescription.
How is NAFLD Activity Score (NAS) calculated in practice? Can you show a worked example?
Inputs: Steatosis grade 1 — 5–33%, Lobular inflammation 1 — <2 foci/20× field, Hepatocyte ballooning 1 — few → Result: NAS 3 /8（Components: S1 + I1 + B1, Band: Borderline / indeterminate range — pattern matters） Inputs: Steatosis grade 0 — <5%, Lobular inflammation 0 — none, Hepatocyte ballooning 0 — none → Result: NAS 0 /8（Components: S0 + I0 + B0, Band: Often not diagnostic of NASH alone (low NAS)）
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