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21
MELD-NaAssesses the severity of chronic liver diseaseChild-Pugh ScoreAssesses the prognosis of chronic liver disease, mainly cirrhosisFIB-4 IndexLiver fibrosis scoring indexAPRIAST to platelet ratio — liver fibrosisMaddrey's DFAlcoholic hepatitis severityGlasgow-BlatchfordUpper GI bleed risk stratificationGAHSGlasgow alcoholic hepatitis scoreMontreal IBDIBD classification — CD & UCMayo ScoreUlcerative colitis activityBISAP ScoreBedside index for severity of pancreatitisCLIF-SOFAOrgan failure scoring in cirrhosisAlcohol ContentStandard drinks & alcohol grams calculatorAARC-ACLFAcute-on-chronic liver failure gradePELD / CR ScorePediatric end-stage liver diseaseHarvey-BradshawCrohn's disease activity indexCTSICT severity index — pancreatitisRockall ScoreGI bleed rebleeding & mortality riskCAGEAlcohol use disorder screening (4 questions)MELD 3.0Updated MELD — sex-inclusive formulaAUDIT ScoreAlcohol use disorders identification testVOCAL-Penn ScorePost-operative mortality risk in cirrhosis surgery

Liver & Cirrhosis

17
ALBI GradeAlbumin-bilirubin liver function grade in HCCUKELD ScoreUK model for end-stage liver diseaseMELD-XIMELD excluding INR — for anticoagulated patientsWest Haven CriteriaHepatic encephalopathy gradingMilan CriteriaLiver transplant eligibility in hepatocellular carcinomaLI-RADS v2018 (CT/MRI)Liver observation category from size, APHE and major featuresBCLC StagingHepatocellular carcinoma stage and treatment allocationSimplified AIH CriteriaSimplified criteria for autoimmune hepatitisRevised Original AIH ScoreIAIHG 1999 comprehensive autoimmune hepatitis scoreSAAGSerum-ascites albumin gradient — cause of ascitesR FactorHepatocellular vs cholestatic pattern in liver injuryCLIF-C ACLFMortality prediction in acute-on-chronic liver failureKing's College CriteriaTransplant criteria in acute liver failureGALAD ScoreHCC detection from gender, age, AFP-L3, AFP and DCPMetroticket 2.0AFP-adjusted up-to-seven for HCC transplant eligibilityRUCAMCausality in drug- and herb-induced liver injuryBaveno VII CriteriacACLD, CSPH and sparing screening endoscopy

Fibrosis & MASLD

8
NAFLD Fibrosis ScoreAdvanced fibrosis probability in MASLD/NAFLDBARD ScoreBMI, AST/ALT ratio, diabetes — MASLD fibrosisFatty Liver IndexPredicts hepatic steatosis from routine labsFibrotic NASH Index (FNI)At-risk NASH probability from AST, HbA1c and HDLNAFLD Activity Score (NAS)Histologic activity grade — steatosis, inflammation, ballooningMEFIB IndexMRE + FIB-4 rule for significant fibrosis (≥F2) in MASLDFAST ScoreFibroScan-AST — at-risk NASH from LSM, CAP and ASTSAFE ScoreSteatosis-Associated Fibrosis Estimator for MASLD in primary care

Pancreas & Biliary

8
Ranson's CriteriaAcute pancreatitis severity at 48 hoursGlasgow-Imrie CriteriaAcute pancreatitis severity — the PANCREAS criteriaHAPSHarmless acute pancreatitis scoreTokyo Guidelines — CholangitisTG18 diagnosis and severity grade for acute cholangitisTokyo Guidelines — CholecystitisTG18 diagnosis and severity grade for acute cholecystitisBiliary Pain (Rome IV)Rome IV — defining biliary-type pain before interventionFunctional Pancreatic SODRome IV — pancreatic sphincter of Oddi disorderRevised Atlanta ClassificationAcute pancreatitis severity — mild, moderately severe, severe

IBD

9
Truelove & Witts CriteriaAcute severe ulcerative colitis — admission decisionUCEISUlcerative colitis endoscopic index of severitySCCAISimple clinical colitis activity index — symptoms onlyCDAICrohn's disease activity index — the trial standardSES-CDEndoscopic severity in Crohn's diseasePUCAIPaediatric ulcerative colitis activity indexTravis (Oxford) CriteriaDay 3 colectomy risk in acute severe ulcerative colitisHo IndexDay 3 steroid failure risk in acute severe ulcerative colitisRutgeerts ScorePostoperative Crohn's recurrence at ileocolonoscopy

GI Bleeding

7
EVendo ScorePredicts oesophageal varices needing treatmentForrest ClassificationPeptic ulcer bleeding — rebleeding risk at endoscopyAIMS65 ScoreUpper GI bleed mortality — five bedside criteriaOakland ScoreSafe-discharge risk for acute lower GI bleedingABC ScoreAge, blood tests, comorbidities — GI bleed mortalitySarin ClassificationEndoscopic classification of gastric varicesEGUS (Gastric Ulcer)Malignancy risk in a gastric ulcer, and who needs repeat endoscopy

Alcohol

2
ABIC ScoreAge, bilirubin, INR, creatinine — alcoholic hepatitisLille ModelSteroid response at day 7 in alcoholic hepatitis

Upper GI

4
Chicago Classification v4.0Oesophageal motility pattern from high-resolution manometryLA Classification (Oesophagitis)Los Angeles grade A–D for erosive oesophagitisPrague C & M CriteriaCircumferential and maximal extent of Barrett's oesophagusEREFS (Eosinophilic Oesophagitis)Endoscopic reference score — oedema, rings, exudates, furrows, stricture

Colorectal

3
Boston Bowel Prep ScaleColonoscopy preparation adequacy by segmentStool Osmotic GapOsmotic vs secretory diarrhoea from stool electrolytesATLAS Score (C. difficile)Predicted response to therapy in Clostridioides difficile infection

Functional GI

37
Bristol Stool ScaleStool form types 1–7 and colonic transitRome IV Criteria for IBSIrritable bowel syndrome diagnosis and subtypeFunctional ConstipationRome IV — two of six items, IBS excludedOpioid-Induced ConstipationRome IV — constipation tied to opioid therapyFunctional DiarrhoeaRome IV — loose stools without predominant painFunctional Bloating / DistensionRome IV — bloating without other bowel disorder criteriaUnspecified Functional Bowel DisorderRome IV — bowel symptoms fitting no other categoryCentrally Mediated Abdominal Pain (CAPS)Rome IV — continuous pain unrelated to gut eventsNarcotic Bowel SyndromeRome IV — opioid-induced hyperalgesia of the gutFaecal Incontinence (Rome IV)Rome IV — the criteria, and why nobody is askedFunctional Anorectal PainLevator ani, unspecified pain and proctalgia fugaxFunctional Defecation DisordersRome IV — dyssynergia and inadequate propulsionInfant RegurgitationRome IV — the happy spitter, and the alarm features that rule it outInfant ColicRome IV — recurrent unexplained crying in a well infant under 5 monthsInfant DyscheziaRome IV — straining before a soft stool, and why not to intervenePaediatric Functional ConstipationRome IV — two of six over one month, with overflow soiling as a criterionToddler's DiarrhoeaRome IV functional diarrhoea of childhood — painless, thriving childPaediatric Cyclic Vomiting SyndromeRome IV — both age bands, with different criteria for eachPaediatric Rumination SyndromeRome IV — infant and child/adolescent criteriaFunctional Nausea & Vomiting (Children)Rome IV — two separate disorders that can be met togetherAerophagiaRome IV — distension that increases through the dayPaediatric Functional DyspepsiaRome IV — four times a month, with PDS and EPS subtypingPaediatric Irritable Bowel SyndromeRome IV — plus the constipation clause clinicians missAbdominal MigraineRome IV — stereotypical incapacitating episodes weeks apartFunctional Abdominal Pain — NOSRome IV — the residual category, reached after the other threeNonretentive Faecal IncontinenceRome IV — soiling without retention, where laxatives make it worseFunctional DyspepsiaRome IV — with PDS and EPS subtypingRumination SyndromeRome IV — effortless regurgitation without retchingCyclic Vomiting SyndromeRome IV — stereotypical episodic vomitingCannabinoid HyperemesisRome IV — CVS pattern relieved by cannabis cessationChronic Nausea & VomitingRome IV — chronic nausea and vomiting syndromeBelching DisordersRome IV — supragastric vs gastric belchingFunctional HeartburnRome IV — heartburn with normal acid exposureReflux HypersensitivityRome IV — normal acid exposure, positive symptom associationFunctional Chest PainRome IV — non-cardiac, non-reflux chest painGlobusRome IV — painless lump-in-throat sensationFunctional DysphagiaRome IV — dysphagia with normal endoscopy and manometry
  1. Calculators
  2. /
  3. NAFLD Activity Score (NAS)
Fibrosis & MASLD

NAFLD Activity Score (NAS)

Histologic activity grade — steatosis, inflammation, ballooning

Low-to-medium-power estimate of the proportion of hepatocytes containing fat.

Number of inflammatory foci per 200× (20× objective) field, averaged across the biopsy.

Ballooned hepatocytes — the feature that distinguishes steatohepatitis from simple steatosis.

A histological score read from a liver biopsy by a pathologist. It grades disease activity only — fibrosis is staged separately (0–4) and is not part of the NAS.

When to use
Use it when a liver biopsy has been taken in metabolic (MASLD/NAFLD) liver disease and you want a reproducible, semiquantitative summary of disease activity — most often in the context of a clinical trial, a research cohort, or serial biopsies where the question is whether activity has improved or worsened. It standardises the way steatosis, inflammation and ballooning are reported so that different pathologists and different time points can be compared. It is not a bedside tool, it is not calculable from blood or imaging, and it is not the instrument by which steatohepatitis is diagnosed.
Why use it
Because before the NAS there was no agreed, numerical way to express how active a fatty liver looked down the microscope, which made trials almost impossible to compare. The NASH CRN system gave each of the three activity features an explicit, defined grade, so that a two-point fall in the NAS — the endpoint many trials adopted — means the same thing in Richmond as in Rome. Its value is standardisation and reproducibility for measuring change, not diagnosis: it turns a qualitative impression into a number that can be tracked, powered for, and audited between observers.
Formula, evidence and interpretation

About the NAFLD Activity Score (NAS)

The NAFLD Activity Score (NAS) is the unweighted sum of three histological features read from a liver biopsy — steatosis (0–3), lobular inflammation (0–3) and hepatocyte ballooning (0–2) — giving a total from 0 to 8. It grades the activity of fatty liver disease, not its stage: fibrosis is scored separately from 0 to 4 and is deliberately not part of the NAS. It was designed by the NASH Clinical Research Network to measure change in trials, and its authors were explicit that it is not a diagnostic algorithm — a biopsy can score 5 without being steatohepatitis if hepatocyte ballooning is absent, and the diagnosis rests on the overall pattern, not the number.

On this page

  • Formula
  • Interpreting the result
  • Inputs
  • What it returns
  • How it is calculated
  • Facts & figures
  • Evidence
  • How it compares
  • Pearls & pitfalls
  • Critical actions
  • Why it exists
  • About the creator
  • Limitations
  • If you are the patient
  • FAQ
  • Related calculators
  • References

Formula

NAS = steatosis (0–3) + lobular inflammation (0–3) + hepatocyte ballooning (0–2)
steatosis
0–3, by percentage of hepatocytes with fat.
lobular inflammation
0–3, by inflammatory foci per 200× field.
hepatocyte ballooning
0–2, by the extent of ballooned hepatocytes.
  • The sum is unweighted — each feature contributes its raw grade, so ballooning (max 2) contributes less to the ceiling than steatosis or inflammation (max 3 each).
  • Fibrosis stage (0–4) is recorded alongside the NAS but is never added into it.
  • The total loses information: report the three component grades, not just the sum.

Interpreting the result

Read the components before the total. In the derivation study, biopsies scoring 0–2 were mostly diagnosed as not steatohepatitis, those scoring 5–8 mostly as definite steatohepatitis, and 3–4 was a borderline zone — but these are correlations, not cut-offs, and the authors warned against using the NAS to make the diagnosis. The single most important check is ballooning: a NAS of 5 built from steatosis 3, inflammation 2 and ballooning 0 is not steatohepatitis, because steatohepatitis requires ballooning. For trials and clinical management, the composite 'at-risk NASH' target — the population in whom treatment is directed — is usually defined as NAS ≥ 4 together with fibrosis stage F2–F3, which is why the activity score and the separate fibrosis stage must always be read as a pair.

ScoreBandWhat it meansAction
0–2Low activityMostly diagnosed as 'not steatohepatitis' in the derivation cohortInterpret with the fibrosis stage and the pattern; a low NAS does not exclude significant fibrosis
3–4Borderline activityBorderline range — neither clearly steatohepatitis nor clearly notDiagnosis rests on the overall pattern; NAS ≥ 4 with F2–F3 is the usual at-risk NASH trial definition
5–8High activityMostly diagnosed as definite steatohepatitis in the derivation cohort — but only when ballooning is presentConfirm ballooning is present; report the fibrosis stage separately and manage accordingly

What the NAFLD Activity Score (NAS) needs (3 inputs)

Steatosis (0–3)
The proportion of hepatocytes containing fat, estimated at low-to-medium power: 0 for under 5%, 1 for 5–33%, 2 for 34–66%, 3 for over 66%. Note that steatosis can paradoxically fall as disease advances toward cirrhosis.
Lobular inflammation (0–3)
The number of inflammatory foci per 200× (20× objective) field: 0 for none, 1 for fewer than 2, 2 for 2–4, 3 for more than 4. Portal inflammation is scored separately and is not counted here.
Hepatocyte ballooning (0–2)
Ballooned, swollen hepatocytes: 0 for none, 1 for a few, 2 for many or prominent. This is the pivotal feature — steatohepatitis is not diagnosed in its absence — and it is also the least reproducible between observers.

What it returns

NAS total (0–8)
The unweighted sum of the three activity grades. It is an activity index, not a fibrosis stage and not a diagnosis of NASH.
Component grades
The individual steatosis, inflammation and ballooning scores, which carry more information than the total — two biopsies with the same NAS can be histologically very different.

How it is calculated

The NAS is one part of the broader NASH CRN histological scoring system, which grades the features of fatty liver disease and, separately, stages fibrosis. The three features chosen for the activity score — steatosis, lobular inflammation and ballooning — were the ones the network found could be graded reproducibly and that captured the activity of the disease. They are summed without weighting to give the 0–8 total. Crucially, the system was validated against pathologists' independent diagnoses and the activity score was found to correlate with, but not define, the diagnosis of steatohepatitis: the diagnosis is a pattern judgement that depends heavily on ballooning and the zonal distribution of injury, which a simple sum cannot represent.

Facts & figures

The three activity components
FeatureGradesBasis
Steatosis0–3< 5% / 5–33% / 34–66% / > 66% of hepatocytes
Lobular inflammation0–3None / < 2 / 2–4 / > 4 foci per 200× field
Hepatocyte ballooning0–2None / few / many

Total 0–8. Fibrosis (0–4) is scored separately and is not part of the NAS.

NAS total vs the pathologist's diagnosis (derivation)
NASPredominant diagnostic category
0–2Not steatohepatitis
3–4Borderline
5–8Definite steatohepatitis

Correlations from the Kleiner cohort, not diagnostic thresholds. Ballooning must be present for a diagnosis of steatohepatitis at any total.

Evidence

Derivation — NASH Clinical Research Network

2005 · n = 976

50 adult liver biopsies scored independently by nine pathologists to design the feature definitions, then applied to 976 biopsies from the NASH CRN. Steatosis, lobular inflammation and ballooning were the features that could be graded reproducibly and were combined into the unweighted 0–8 activity score, with fibrosis staged separately.

The activity score correlated with the independent diagnosis of steatohepatitis (higher scores, higher likelihood of a 'definite' diagnosis) but did not define it. Interobserver agreement was substantial for steatosis and fibrosis and only moderate for ballooning and inflammation.

Clarification of what NAS does and does not mean

2011

A subsequent NASH CRN analysis (Brunt and colleagues) compared the NAS with the pathologists' diagnostic categorisation across the cohort, directly testing whether the number could stand in for the diagnosis.

NAS and the histopathological diagnosis carried distinct meanings: some biopsies with a high NAS were not steatohepatitis and some with a lower NAS were, confirming that the score measures activity and must not be used as a diagnostic threshold.

How it compares

NAFLD Activity Score (NAS) vs Fibrotic NASH Index (FNI)

They are the reference and its surrogate — the NAS is read from the biopsy that the blood-based FNI is trying to predict, so use FNI to decide who needs a biopsy and the NAS to score the biopsy once taken.

The FNI estimates the probability that a biopsy would show at-risk NASH, which is defined by a NAS of at least 4 together with fibrosis of at least F2. In other words the NAS (plus the separate fibrosis stage) is the ground truth the FNI is calibrated against. They are not alternatives: one is a non-invasive triage score, the other is the histological measurement it is a stand-in for.

Open the Fibrotic NASH Index (FNI) calculator →

NAFLD Activity Score (NAS) vs FIB-4

Orthogonal measurements — the NAS grades activity on biopsy while FIB-4 estimates fibrosis from blood, so they capture different axes of the same disease and neither substitutes for the other.

FIB-4 is a non-invasive estimate of advanced fibrosis and says nothing about inflammation or ballooning; the NAS grades exactly those activity features and deliberately excludes fibrosis. A patient can have a high FIB-4 with a modest NAS (advanced but quiescent disease) or a high NAS with a low FIB-4 (active but not yet fibrotic), which is precisely why activity and stage are recorded separately.

Open the FIB-4 calculator →

NAFLD Activity Score (NAS) vs SAF score (Steatosis, Activity, Fibrosis)

The SAF score reports activity as ballooning plus inflammation only (0–4) and keeps steatosis and fibrosis as separate axes — arguably a cleaner separation than the NAS, which folds steatosis into the activity total.

Bedossa's SAF system grades Steatosis (0–3), Activity (ballooning 0–2 plus lobular inflammation 0–2, total 0–4) and Fibrosis (0–4) as three independent components. Because steatosis is a marker of fat load rather than of injurious activity, excluding it from the activity term is conceptually tidier than the NAS, which adds it in. Many European centres report SAF; the NASH CRN NAS remains the more widely used framework in trials.

Pearls & pitfalls

  • The NAS is an activity score, not a diagnosis. A total of 5 is not steatohepatitis if ballooning is 0, and the diagnosis is always a pattern judgement.
  • Fibrosis is not in the NAS. A patient can have a low activity score and advanced fibrosis at the same time — read the separate fibrosis stage every time.
  • The total hides the components. Steatosis 3 + inflammation 2 + ballooning 0 and steatosis 1 + inflammation 2 + ballooning 2 both score 5 but mean very different things.
  • Ballooning is the least reproducible feature between pathologists, and it is the one the diagnosis hinges on — treat borderline ballooning cautiously.
  • Steatosis can fall as disease advances. 'Burnt-out' NASH cirrhosis may show little fat and a deceptively low NAS.
  • Biopsy sampling variability is real: a 1.5 cm core samples about 1/50,000th of the liver, and activity is patchy, so a single NAS carries genuine uncertainty.
  • The at-risk NASH population targeted by treatment is defined by NAS ≥ 4 and fibrosis F2–F3 together — the activity score alone does not identify it.

Critical actions

  • Always report the fibrosis stage alongside the NAS; the two answer different questions and management follows the stage as much as the activity.
  • Confirm hepatocyte ballooning is present before a biopsy with a high NAS is treated as steatohepatitis.
  • Record the three component grades, not only the total, so that change over time is interpretable.
  • When using the NAS to judge treatment response, look for the trial-standard ≥ 2-point reduction without worsening of fibrosis, rather than any change in the total.
  • Interpret a low NAS in context — it does not exclude significant fibrosis or a prior diagnosis of steatohepatitis.

Why this score exists

The NASH CRN was explicit about what they had built and what they had not. The activity score was intended as a tool for measuring change — in trials and over serial biopsies — and they cautioned specifically against its use as a diagnostic device or as a way of grading severity in place of the pathologist's overall assessment. The diagnosis of steatohepatitis, they argued, is a gestalt that weighs the pattern of injury, particularly ballooning and its zonal distribution, in a way that an unweighted sum cannot. Much of the later confusion around the NAS — biopsies labelled NASH on the strength of a number, or a fall in the score read as more than it is — comes from using it for the diagnostic job its own authors said it was not designed to do.

About the creator

  • David E. Kleiner

    First author, 2005 derivation study

    Led the NASH Clinical Research Network pathology committee that designed and validated the histological scoring system.

  • Arun J. Sanyal

    Senior author

    Co-founded the NASH CRN whose network produced the score.

Limitations

  • It grades activity only — it does not stage fibrosis, estimate prognosis, or diagnose steatohepatitis, all of which require separate assessment.
  • It requires a liver biopsy, which carries sampling variability and a small procedural risk, and cannot be derived from blood or imaging.
  • Interobserver agreement is only moderate for ballooning and lobular inflammation, the features that matter most for the diagnosis.
  • The unweighted total obscures the components and can equate biopsies of very different clinical meaning.
  • Steatosis, and therefore the NAS, can decline as disease progresses to cirrhosis, understating advanced disease.
  • It was designed to measure change, so a single cross-sectional value is less informative than a paired before-and-after comparison.

If you are the patient

The NAFLD Activity Score is not a blood test or a scan — it is a number a specialist doctor (a pathologist) works out by looking at a small sample of your liver under the microscope after a biopsy. They grade three things: how much fat is in the liver cells, how much inflammation there is, and whether liver cells are swollen ('ballooned'). Added together these give a score from 0 to 8 that describes how active the fatty liver disease is. It is important to know two things. First, this score is about activity, not scarring — the amount of scarring (fibrosis) is measured on its own scale and matters just as much for your outlook. Second, the number on its own does not diagnose the more serious form of the disease; the pathologist decides that from the overall picture, especially whether the liver cells are ballooned. So your team reads this score together with the scarring stage and the whole biopsy, not in isolation.

Frequently asked questions

What is the NAFLD Activity Score (NAS)?#

The NAS is a histological score, from 0 to 8, that a pathologist calculates from a liver biopsy by adding grades for steatosis (0–3), lobular inflammation (0–3) and hepatocyte ballooning (0–2). Developed by the NASH Clinical Research Network, it measures the activity of metabolic fatty liver disease and is used mainly to track change in clinical trials.

Does a NAS of 5 or more mean NASH?#

Not necessarily. In the derivation cohort most biopsies scoring 5–8 were diagnosed as definite steatohepatitis, but that is a correlation, not a rule. Steatohepatitis requires hepatocyte ballooning, so a biopsy scoring 5 with a ballooning grade of 0 is not steatohepatitis. The diagnosis is made on the overall pattern by the pathologist, not on the number.

Is fibrosis part of the NAS?#

No. Fibrosis is staged separately from 0 to 4 in the same NASH CRN system and is deliberately excluded from the NAS. This is important because activity and fibrosis can diverge — a patient can have advanced fibrosis with only modest activity, or high activity with little fibrosis — so the two must always be read together.

What is 'at-risk NASH' in terms of the NAS?#

At-risk NASH, the population in whom treatment and trials are focused, is usually defined as a NAS of at least 4 combined with fibrosis stage F2 or F3. It therefore depends on both the activity score and the separate fibrosis stage, not on the NAS alone.

How is the NAS different from the SAF score?#

Both grade fatty liver histology, but the SAF score reports Activity as ballooning plus lobular inflammation only (0–4) and keeps Steatosis and Fibrosis as separate axes, whereas the NAS folds steatosis into its 0–8 activity total. Excluding steatosis from the activity term, as SAF does, is conceptually cleaner, but the NAS remains the more common framework in trials.

Can the NAS be calculated without a biopsy?#

No. The NAS is a histological score and can only be read from a liver biopsy. Non-invasive tools such as the Fibrotic NASH Index, FAST or MAST are designed to estimate the probability that a biopsy would show at-risk NASH, but they produce a probability, not a NAS.

Related calculators

  • Fibrotic NASH Index (FNI) — At-risk NASH probability from AST, HbA1c and HDL
  • FIB-4 Index — Liver fibrosis scoring index
  • NAFLD Fibrosis Score — Advanced fibrosis probability in MASLD/NAFLD
  • APRI — AST to platelet ratio — liver fibrosis

References

Original / primary reference

  1. Kleiner DE, Brunt EM, Van Natta M, et al. Design and validation of a histological scoring system for nonalcoholic fatty liver disease. Hepatology. 2005;41(6):1313-1321.

Validation / interpretation

  1. Brunt EM, Kleiner DE, Wilson LA, et al. Nonalcoholic fatty liver disease (NAFLD) activity score and the histopathologic diagnosis in NAFLD: distinct clinicopathologic meanings. Hepatology. 2011;53(3):810-820.
  2. Bedossa P, Poitou C, Veyrie N, et al. Histopathological algorithm and scoring system for evaluation of liver lesions in morbidly obese patients (SAF score). Hepatology. 2012;56(5):1751-1759.
  3. Sanyal AJ, Chalasani N, Kowdley KV, et al. Pioglitazone, vitamin E, or placebo for nonalcoholic steatohepatitis (PIVENS). N Engl J Med. 2010;362(18):1675-1685.

Clinical practice guidelines & nomenclature

  1. Rinella ME, Lazarus JV, Ratziu V, et al. A multisociety Delphi consensus statement on new fatty liver disease nomenclature. Hepatology. 2023;78(6):1966-1986.
  2. EASL-EASD-EASO Clinical Practice Guidelines on the management of metabolic dysfunction-associated steatotic liver disease (MASLD). J Hepatol. 2024;81(3):492-542.
  3. Rinella ME, Neuschwander-Tetri BA, Siddiqui MS, et al. AASLD Practice Guidance on the clinical assessment and management of nonalcoholic fatty liver disease. Hepatology. 2023;77(5):1797-1835.

Further reading

  1. Tavaglione F, De Vincentis A, Jamialahmadi O, et al. Development and Validation of a Score for Fibrotic Nonalcoholic Steatohepatitis (FNI). Clin Gastroenterol Hepatol. 2023;21(6):1523-1532.e1.

Last updated July 30, 2026. Clinical knowledge base written and curated by GastroAGI Team from primary medical literature.

Written from primary literature and not yet independently clinically reviewed.

For use by qualified healthcare professionals. This calculator supports clinical judgement and does not replace it.