Metabolic dysfunction–associated steatotic liver disease (MASLD) is a complex disease closely related to obesity and other cardiometabolic processes. It affects millions worldwide and is on track to markedly increase cases of end-stage liver disease requiring transplantation as well as cases of hepatocellular carcinoma in the coming years. Noninvasive assessments such as the Fibrosis-4 index are useful tools for identifying those at risk of clinically significant fibrosis and cirrhosis caused by MASLD. Other noninvasive tests, including liver stiffness measured with transient elastography, help to stratify risk, guide therapy, and inform surveillance and prognosis. Weight loss is the cornerstone of treatment for MASLD. The condition can progress to metabolic dysfunction–associated steatohepatitis (MASH), characterized by stage F2 or F3 fibrosis, and ultimately cirrhosis (stage F4 fibrosis). For patients with MASH who have comorbid obesity, bariatric surgery or pharmacologic approaches to weight loss should be considered. Progression to advanced fibrosis and cirrhosis (stage F3 or F4) is slow and depends on multiple factors. Screening for hepatocellular carcinoma with abdominal ultrasonography and alpha-fetoprotein testing every 6 months is indicated in patients with MASH-related cirrhosis.
Mitchell JT, Porter CL. Hepatitis Overview: Metabolic Dysfunction–Associated Steatotic Liver Disease. FP Essent. 2026;566:7-14.
Case 1. LG is a 53-year-old man presenting for routine chronic disease management. He received a type 2 diabetes diagnosis about 6 months ago, and laboratory tests at that time showed elevated levels of aspartate transferase (AST) and alanine transferase (ALT). He has no right upper quadrant pain. He has class II obesity, with a body mass index (BMI) of 38 kg/m2, and drinks alcohol socially about once a month. LG has no other risk factors for chronic liver disease. On examination, you find no palpable hepatomegaly. He is concerned about his liver and asks what he should do to be healthy again.
Diagnostic Criteria
In 2023, the American Association for the Study of Liver Diseases along with other professional organizations established a consensus statement with new nomenclature and diagnostic criteria for the diseases previously known as nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH).1 The diseases were renamed metabolic dysfunction–associated steatotic liver disease (MASLD) and metabolic dysfunction–associated steatohepatitis (MASH), respectively. The term nonalcoholic excludes many patients with both alcohol use and metabolic dysfunction contributing to liver disease; additionally, (non)alcoholic and fatty are stigmatizing.
MASLD can progress to MASH, characterized by steatosis causing hepatocellular injury.2 In brief, toxic lipid compounds accumulate in the liver, prompting an inflammatory response that ultimately damages hepatocytes.3 In addition to changing nomenclature, the consensus statement established MASLD as an affirmative diagnosis rather than a diagnosis of exclusion. Patients with evidence of steatosis on imaging and the presence of one or more cardiometabolic risk factors have MASLD. Female patients who consume 20 to 50 g of alcohol daily (1.5-3.5 standard drinks in the United States) or male patients who consume 30 to 60 g of alcohol daily (2-4 standard drinks) with concurrent MASLD have a separate condition known as metabolic dysfunction and alcohol-associated liver disease.4
Notably, the new definition of MASLD describes 99% of patients with NAFLD.4 Therefore, previous data applied to patients with NAFLD apply to patients with MASLD, and the terms can be used interchangeably when relying on data procured before the terminology change.
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