The New Liver Lexicon

NASH by any other name would still be fatty liver (but going forward call it SLD) 

Mark W. Tengowski, D.V.M., M.S., Ph.D. – Director of Medical and Scientific Affairs at Clario

For scientists, nomenclature plays an instrumental role in communication, research, and treatment. For professionals in hepatology, the changing terminology for fatty liver disease has recently taken a pivotal shift. Spearheaded by the AASLD NAFLD Nomenclature consensus group, this international exercise is more than a mere change in acronyms. It seeks to provide a more precise representation of the disease in question and promote a clearer understanding for both clinical and research purposes. 

Understanding the Shifts 

Let’s delve into the details of these recent changes: 

• From Broad NAFLD to SLD: The overarching term for fatty liver disease is now Steatotic Liver Disease (SLD). This modern term encapsulates the vast spectrum of fatty liver diseases while maintaining specificity. 

• Refining NAFLD: Traditionally, Non-alcoholic Fatty Liver Disease (NAFLD) represented fatty liver without a significant alcohol history. The new terminology, Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD), adds depth to this definition by associating it with fatty liver and at least one cardiovascular risk factor. 

• Accounting for Alcohol: The term MetALD is introduced for MASLD individuals who have a history of high alcohol consumption. This distinction ensures a clear differentiation between fatty liver conditions induced by metabolic dysfunction and those aggravated by alcohol. 

• The Enigmatic Cryptogenic SLD: For those with fatty liver diseases that don’t fit into the aforementioned categories, having no apparent metabolic parameters or discernible cause for their liver fat, the term Cryptogenic SLD is now in play. 

• NASH to MASH: To better capture the essence of Non-Alcoholic Steatohepatitis (NASH) as it relates to metabolic dysfunctions, the term has been updated to Metabolic Dysfunction-Associated Steatohepatitis (MASH). This change, while subtle, solidifies the association of the disease with metabolic irregularities. 

Why the Change?

One might ask, why the need for these nuanced shifts in terminology? The consensus group’s undertaking of the Delphi exercise provided significant justifications: 

• Diagnostic Precision: The updated terms enable more accurate diagnoses. By specifying conditions like MASLD and MetALD, clinicians can pinpoint the root causes and associated risk factors of fatty liver diseases in their patients. 

• Clinical Trials and Research: For researchers, the updated nomenclature is indispensable. It ensures that clinical trial subjects are categorized more effectively, leading to more accurate study results and ultimately better patient care. 

• Increased Awareness and Adaptation: As the medical community worldwide becomes accustomed to these terms, the benefits will ripple out. A unified understanding of these diseases can lead to better communication among professionals, more informed patients, and advanced research. 

A robust and precise nomenclature system is paramount in a world where science and medicine are advancing at lightning speed. The transition from terms like NASH to the more descriptive SLD and MASH is a reflection of the scientific community’s commitment to understanding, treating, and communicating about these diseases with utmost clarity. With the embrace of this modernized terminology, both the diagnostic and research facets of hepatology are poised for accelerated progress.