Non-alcoholic fatty liver disease classification

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Vamsikrishna Gunnam M.B.B.S [2]Parth Vikram Singh, MBBS [3]

Overview

Non-alcoholic fatty liver (NAFLD) disease may be classified based on clinical presentation into non-alcoholic fatty liver and non-alcoholic steatohepatitis.

Clinical Classification

Non-alcoholic fatty liver disease may be classified based on clinical presentation into non-alcoholic fatty liver and non-alcoholic steatohepatitis.^[1]^[2]^[3]

Based on clinical presentation
Non-alcoholic fatty liver	Non-alcoholic steatohepatitis
Benign	Aggressive
Non-progressive	Can progress to cirrhosis Rarely can give rise to hepatocellular carcinoma
Based on Etiology
Primary NAFLD	If the cause of the liver disease was unknown.
Secondary NAFLD	If the cause of the liver disease is secondary to: Surgery for morbid obesity An adverse drug effect Conditions such as abetalipoproteinemia or Wilson’s disease

Steatotic liver disease may be subclassified according to the presence of cardiometabolic risk factors, alcohol intake, and other causes of hepatic steatosis.^[4]

Category	Definition
MASLD	Hepatic steatosis with at least 1 cardiometabolic risk factor, alcohol intake less than 140 g/week in women and less than 210 g/week in men, and no other known cause of hepatic steatosis
Metabolic dysfunction and alcohol-related liver disease (MetALD)	Hepatic steatosis with metabolic dysfunction and alcohol intake of 140-350 g/week in women or 210-420 g/week in men
Alcohol-associated liver disease	Alcohol intake greater than 350 g/week in women or greater than 420 g/week in men
Cryptogenic steatotic liver disease	Hepatic steatosis without cardiometabolic risk factors and without an identifiable cause
Specific-etiology steatotic liver disease	Hepatic steatosis due to another identifiable cause, such as drug-induced liver injury, iron overload, genotype 3 hepatitis C, Wilson disease, lysosomal acid lipase deficiency, hypobetalipoproteinemia, inborn errors of metabolism, celiac disease, malnutrition, or HIV infection

One standard drink is approximately equivalent to 10 g of alcohol, corresponding approximately to 12 oz of beer, 5 oz of wine, or 1.5 oz of 80-proof distilled spirits.

Histopathological classification

Histological classification of NAFLD includes grading and staging.

Grade: Depending on degree of steatosis and necro-inflammatory activity
Stage: Depending on degree of fibrosis.

Grading

NAFLD activity score is employed for grading steatohepatitis of NASH. NAS represents the sum of scores for steatosis, lobular inflammation, and ballooning.^[5]

Component	Range	Score
Steatosis	<5%	0
	5-33%	1
	34-66%	2
	>66%	3
Lobular Inflammation	None	0
	<2 focci	1
	2-4	2
	>4	3
Hepatocyte -Balloning	None	0
	Few ballooned cells	1
	Many ballooned cells	2
Interpretation	0-2	Non-diagnostic
	3-4	Borderline
	5-8	Diagnostic

Staging

Based on liver biopsy histology, liver fibrosis in MASLD is scored using a 5-stage scale:

Stage	Histologic description
F0	Absence of fibrosis
F1	Perisinusoidal or portal fibrosis
F2	Perisinusoidal and portal or periportal fibrosis
F3	Septal and bridging fibrosis
F4	Cirrhosis

References

↑ Hashimoto E, Tokushige K, Ludwig J (2015). “Diagnosis and classification of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis: Current concepts and remaining challenges”. Hepatol Res. 45 (1): 20–8. doi:10.1111/hepr.12333. PMID 24661406.
↑ Cobbina E, Akhlaghi F (2017). “Non-alcoholic fatty liver disease (NAFLD) – pathogenesis, classification, and effect on drug metabolizing enzymes and transporters”. Drug Metab Rev. 49 (2): 197–211. doi:10.1080/03602532.2017.1293683. PMC 5576152. PMID 28303724.
↑ Monteiro JM, Monteiro GM, Caroli-Bottino A, Pannain VL (2014). “Nonalcoholic fatty liver disease: different classifications concordance and relationship between degrees of morphological features and spectrum of the disease”. Anal Cell Pathol (Amst). 2014: 526979. doi:10.1155/2014/526979. PMC 4333905. PMID 25763333.
↑ Tilg H, Petta S, Stefan N, Targher G (January 2026). “Metabolic Dysfunction-Associated Steatotic Liver Disease in Adults: A Review”. JAMA. 335 (2): 163–174. doi:10.1001/jama.2025.19615. PMID 41212550 Check |pmid= value (help).
↑ Vizuete J, Camero A, Malakouti M, Garapati K, Gutierrez J (2017). “Perspectives on Nonalcoholic Fatty Liver Disease: An Overview of Present and Future Therapies”. J Clin Transl Hepatol. 5 (1): 67–75. doi:10.14218/JCTH.2016.00061. PMC 5411359. PMID 28507929.

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[pmid24661406-1] Hashimoto E, Tokushige K, Ludwig J (2015). “Diagnosis and classification of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis: Current concepts and remaining challenges”. Hepatol Res. 45 (1): 20–8. doi:10.1111/hepr.12333. PMID 24661406.

[pmid28303724-2] Cobbina E, Akhlaghi F (2017). “Non-alcoholic fatty liver disease (NAFLD) – pathogenesis, classification, and effect on drug metabolizing enzymes and transporters”. Drug Metab Rev. 49 (2): 197–211. doi:10.1080/03602532.2017.1293683. PMC 5576152. PMID 28303724.

[pmid25763333-3] Monteiro JM, Monteiro GM, Caroli-Bottino A, Pannain VL (2014). “Nonalcoholic fatty liver disease: different classifications concordance and relationship between degrees of morphological features and spectrum of the disease”. Anal Cell Pathol (Amst). 2014: 526979. doi:10.1155/2014/526979. PMC 4333905. PMID 25763333.

[pmid41212550-4] Tilg H, Petta S, Stefan N, Targher G (January 2026). “Metabolic Dysfunction-Associated Steatotic Liver Disease in Adults: A Review”. JAMA. 335 (2): 163–174. doi:10.1001/jama.2025.19615. PMID 41212550 Check |pmid= value (help).

[pmid28507929-5] Vizuete J, Camero A, Malakouti M, Garapati K, Gutierrez J (2017). “Perspectives on Nonalcoholic Fatty Liver Disease: An Overview of Present and Future Therapies”. J Clin Transl Hepatol. 5 (1): 67–75. doi:10.14218/JCTH.2016.00061. PMC 5411359. PMID 28507929.

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