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Gastroenterology · Pathology

NAFLD Activity Score calculator

Enter the published formula inputs below to calculate and interpret this score.

Clinical inputs

Steatosis grade

The 2016 restatement prints grade 1 as 5% to 33% and grade 2 as 33% to 67%, so exactly 33% is on both rows. Grade 0 is under 5%. Grade 3 is over 67%. Enter the grade on the biopsy report.

Lobular inflammation grade

Grades run from 0 to 3: no foci, fewer than 2 foci, 2 through 4 foci, or more than 4 foci in one field. The 2016 table prints 20× and earlier citations of the same system print 200×. The focus counts are the same.

Ballooning grade

None is 0, few ballooned hepatocytes is 1, and many is 2. Fibrosis is not added.

Result

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Clinical inputs

  • Steatosis grade
  • Lobular inflammation grade
  • Ballooning grade

Primary source

Kleiner DE et al. Design and validation of a histological scoring system for nonalcoholic fatty liver disease. Hepatology. DOI: 10.1002/hep.20701. PMID: 15915461. The activity score is the unweighted sum of steatosis, lobular inflammation, and hepatocellular ballooning. Fibrosis is staged separately and is not added. In that study, scores of 5 or higher correlated with a diagnosis of NASH, and biopsies with scores less than 3 were diagnosed as not NASH. Brown GT, Kleiner DE. Metabolism. DOI: 10.1016/j.metabol.2015.11.008. PMID: 26775559 restated the same sum as steatosis 0–3, lobular inflammation 0–3, and ballooning 0–2. (2005)

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