Steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is one of the most common causes of chronic liver disease in the developed world.

It is a spectrum of disease, ranging from hepatic fat accumulation without inflammation to steatohepatitis, fibrosis, cirrhosis, and end-stage liver disease.

MASLD is considered the hepatic manifestation of metabolic syndrome and is associated with obesity, dyslipidemia, and type 2 diabetes mellitus.

The diagnosis of MASLD is based on exclusion of other etiologies of steatotic liver disease, such as alcohol use, and supportive laboratory tests and imaging. Liver biopsy and histology is the gold standard for diagnosis, and is performed for patients at higher risk of fibrosis or steatohepatitis.

Lifestyle modification, including weight loss, physical activity, and dietary changes, is the first-line therapy. There are no licensed drug treatments, although use of pioglitazone or vitamin E may be considered for selected patients.

Steatotic liver disease (SLD) is an overarching term to encompass the various etiologies of steatosis.[1]Kanwal F, Neuschwander-Tetri BA, Loomba R, et al. Metabolic dysfunction-associated steatotic liver disease: update and impact of new nomenclature on the American Association for the Study of Liver Diseases practice guidance on nonalcoholic fatty liver disease. Hepatology. 2024 May 1;79(5):1212-9. https://www.doi.org/10.1097/HEP.0000000000000670 http://www.ncbi.nlm.nih.gov/pubmed/38445559?tool=bestpractice.com ​ To more accurately reflect the pathogenesis of fatty liver, a new nomenclature has been suggested.​[1]Kanwal F, Neuschwander-Tetri BA, Loomba R, et al. Metabolic dysfunction-associated steatotic liver disease: update and impact of new nomenclature on the American Association for the Study of Liver Diseases practice guidance on nonalcoholic fatty liver disease. Hepatology. 2024 May 1;79(5):1212-9. https://www.doi.org/10.1097/HEP.0000000000000670 http://www.ncbi.nlm.nih.gov/pubmed/38445559?tool=bestpractice.com [2]American Association for the Study of Liver Diseases. New MASLD nomenclature. Jun 2023 [internet publication]. https://www.aasld.org/new-masld-nomenclature ​​

Metabolic dysfunction-associated steatotic liver disease (MASLD) previously known as nonalcoholic fatty liver disease (NAFLD), is the evidence of SLD (imaging or histologic) in the absence of secondary causes of hepatic fat accumulation, such as significant alcohol consumption.​[1]Kanwal F, Neuschwander-Tetri BA, Loomba R, et al. Metabolic dysfunction-associated steatotic liver disease: update and impact of new nomenclature on the American Association for the Study of Liver Diseases practice guidance on nonalcoholic fatty liver disease. Hepatology. 2024 May 1;79(5):1212-9. https://www.doi.org/10.1097/HEP.0000000000000670 http://www.ncbi.nlm.nih.gov/pubmed/38445559?tool=bestpractice.com [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 May 1;77(5):1797-835. https://journals.lww.com/hep/fulltext/2023/05000/aasld_practice_guidance_on_the_clinical_assessment.31.aspx http://www.ncbi.nlm.nih.gov/pubmed/36727674?tool=bestpractice.com ​​​​ Pure MASLD encompasses patients with SLD and at least one of five cardiometabolic risk factors. MetALD describes those with MASLD who consume greater amounts of alcohol per week (140-350 g/week for females and 210-420 g/week for males) and have SLD and cardiometabolic risk factors.​[1]Kanwal F, Neuschwander-Tetri BA, Loomba R, et al. Metabolic dysfunction-associated steatotic liver disease: update and impact of new nomenclature on the American Association for the Study of Liver Diseases practice guidance on nonalcoholic fatty liver disease. Hepatology. 2024 May 1;79(5):1212-9. https://www.doi.org/10.1097/HEP.0000000000000670 http://www.ncbi.nlm.nih.gov/pubmed/38445559?tool=bestpractice.com [2]American Association for the Study of Liver Diseases. New MASLD nomenclature. Jun 2023 [internet publication]. https://www.aasld.org/new-masld-nomenclature ​​

MASLD can be categorized as metabolic dysfunction-associated steatotic liver (MASL), previously known as nonalcoholic fatty liver (NAFL), or metabolic dysfunction-associated steatohepatitis (MASH), previously known as nonalcoholic steatohepatitis (NASH), depending on histologic features. MASL is the presence of SLD without evidence of hepatocellular injury in the form of hepatocyte ballooning. MASH is the presence of SLD and inflammation with hepatocyte injury (e.g., ballooning), with or without fibrosis.[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 May 1;77(5):1797-835. https://journals.lww.com/hep/fulltext/2023/05000/aasld_practice_guidance_on_the_clinical_assessment.31.aspx http://www.ncbi.nlm.nih.gov/pubmed/36727674?tool=bestpractice.com ​ This distinction is important for prognosis because MASH may progress to cirrhosis and liver failure. The risk of MASL progressing to cirrhosis or liver failure is minimal.[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 May 1;77(5):1797-835. https://journals.lww.com/hep/fulltext/2023/05000/aasld_practice_guidance_on_the_clinical_assessment.31.aspx http://www.ncbi.nlm.nih.gov/pubmed/36727674?tool=bestpractice.com ​​

This topic focuses on MASLD. See also Alcohol-related liver disease.