Sarcopenia and metabolic dysfunction associated steatotic liver disease: Time to address both.

Abstract

Sarcopenia and metabolic dysfunction associated steatotic liver disease (MASLD) are closely intertwined. Sarcopenia, traditionally a disease of the older adult and chronic disease population, has been closely studied as one of the pathophysiologic conditions at play in the development of MASLD. They share similar risk factors of insulin resistance and physical inactivity. Given similar pathophysiology along the liver-muscle axis, sarcopenia has been studied as a risk factor for MASLD, and vice versa. Current research suggests a bidirectional relationship. Given the chronicity of MASLD as a chronic inflammatory liver disease, it can break down muscle mass and lead to sarcopenia, while sarcopenia promotes intramuscular lipid accumulation that releases cytokines that can aggravate inflammation in the liver. However, for the longest time, a lack of consensus definition for MASLD and sarcopenia made it difficult to study their relationship and outcomes. A recent nomenclature update to diagnosing MASLD has made it easier for researchers to identify cohorts for study. However, no gold standard technique to measure muscle mass or consensus sarcopenia definition has been identified yet. Future studies are needed to reach a consensus and reduce diagnostic variation. With similar pathophysiology and shared risk factors between the two diseases, future research may also identify potential therapeutic targets along the liver-muscle axis that would benefit both sarcopenia and MASLD in order to maximize their outcomes.