NAFLD, it’s been a fun ride. And MAFLD, it feels like we hardly knew ya.

Enter MASLD, the newest name in what feels like the ever-shifting nomenclature of liver steatosis. An international panel has endorsed replacing “nonalcoholic fatty liver disease” (NAFLD) with “metabolic dysfunction-associated steatotic liver disease” (MASLD), creating a downstream cascade of new diagnostic entities (and abbreviations). 

MASLD has become not only the most common chronic liver disease in the world but also one of the most common chronic diseases overall, affecting an estimated 30-40% (!) of the world’s population. This fact alone contradicts the implication that NAFLD refers to an uncommon diagnosis of exclusion. Furthermore, both “alcoholic” and “fatty” have stigmatizing overtones leading to their removal from the updated diagnostic names. Meanwhile, older diagnostic criteria assumed that most liver pathology resulted from a single cause, but clinicians often encounter multiple liver insults in the same patient.

Source: Rinella et al. Hepatology. 2023

So the fatty liver has become the steatotic liver, and “steatotic liver disease” (SLD) is now the preferred umbrella term for MASLD and ALD (alcohol-related liver disease), as well as for cases of steatosis caused by drugs and genetic factors, and for cases without clear etiology (cryptogenic SLD). A diagnosis of MASLD refers to liver steatosis in the presence of only a single metabolic risk factor (e.g., overweight, hyperglycemia, T2DM, HTN, dyslipidemia). Other causes of steatosis must be excluded, but notably, a diagnosis of MASLD does not require the absence of viral hepatitis, as a diagnosis of NAFLD did. Nor does a diagnosis of MASLD require the absence of alcohol use: Patients with MASLD who drink more alcohol than the recommended maximum (20-30 g daily) but less than the threshold for diagnosis of ALD (50-60 g daily) now will be said to have MetALD (MASLD and increased alcohol consumption).

Source: Rinella et al. Hepatology. 2023
Source: Rinella et al. Hepatology. 2023

Among patients with inflammatory steatosis, MASH (metabolic dysfunction-associated steatohepatitis) will replace NASH (nonalcoholic steatohepatitis). Those with nonprogressive disease at the other end of the clinical spectrum will be said to have MASL (metabolic dysfunction-associated liver) rather than NAFL (nonalcoholic fatty liver). Meanwhile, the recently coined term MAFLD (metabolic dysfunction-associated fatty liver disease) has been retired, with most of these patients folded into the MASLD category.

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