Non-Alcoholic Fatty Liver Disease - Liver Fat Score (NAFLD-LFS) Calculator

Non-Alcoholic Fatty Liver Disease - Liver Fat Score (NAFLD-LFS) Calculator for Endocrinology. The tool reports whether the unrounded score is above the original -0.640 cutoff. Equality is labeled at the cutoff, not proof of absence of steatosis. This score is distinct from the separate liver-fat percentage equation described in the original paper.

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

How this calculator works

NAFLD-LFS = -2.89 + 1.18 x IDF metabolic syndrome + 0.45 x diabetes code + 0.15 x insulin + 0.04 x AST - 0.94 x AST/ALT. Metabolic syndrome is 1 if present and 0 if absent. Diabetes is 2 if present and 0 if absent, so its contribution is 0.90, not 0.45.

When to use this calculator

Use for reproducing the historical score or discussing a screening estimate. Establish the IDF input first: that definition requires central obesity plus additional factors. The separate harmonized metabolic-syndrome tool on this site is not an automatic substitute.

Inputs used

  • Metabolic-syndrome status established using the original IDF definition
  • Established type 2 diabetes status
  • Fasting insulin in micro-units/mL, numerically equal to mU/L
  • AST and ALT in U/L

Clinical interpretation

The tool reports whether the unrounded score is above the original -0.640 cutoff. Equality is labeled at the cutoff, not proof of absence of steatosis. This score is distinct from the separate liver-fat percentage equation described in the original paper.

Worked example

With IDF metabolic syndrome, type 2 diabetes, insulin 10, AST 30 and ALT 40, the score is -2.89 + 1.18 + 0.90 + 1.50 + 1.20 - 0.705 = 1.185. Without diabetes, otherwise identical inputs give 0.285. ALT zero is rejected rather than producing infinity.

Limitations and safety notes

Fasting conditions, insulin assays, study population and metabolic-syndrome definition affect comparability. The result does not diagnose MASH, quantify fibrosis or select medication. A historical NAFLD model has not thereby been revalidated for all modern steatotic-liver categories.

Frequently asked questions

Is 1.185 the percentage of liver fat?

No. It is an index. Percent liver fat requires a different equation or an appropriate measurement.

Can diabetes simply be entered as one?

The interface asks yes or no and applies the source coding internally: yes contributes 0.90 to the score.

References

  • Original Kotronen 2009 derivation identity, MRS outcome, score vs separate liver-fat percentage equation and -0.640 cutoff. https://pubmed.ncbi.nlm.nih.gov/19524579/
  • Primary cohort methods: full NAFLD-LFS coefficient equation, diabetes yes=2, insulin and enzyme units. https://www.mdpi.com/2072-6643/15/13/2880
  • Primary cohort method specifies IDF metabolic-syndrome input; not relied on for its enzyme-unit text. https://academic.oup.com/jcem/article/106/1/e118/5943446
  • Original IDF definition: central obesity prerequisite plus two factors, distinct from later harmonized definition. https://idf.org/media/uploads/2023/05/attachments-30.pdf

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.

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