Sarcopenia and Frailty in Liver Cirrhosis.

Skeletal muscle is the largest organ in the body, and skeletal muscle atrophy results from a shift in the balance of protein synthesis and degradation toward protein breakdown. Primary sarcopenia is defined as a loss of skeletal muscle mass and strength or physical function due to aging, and secondary sarcopenia is defined as a loss of skeletal muscle mass and strength or physical function due to underlying diseases. Liver cirrhosis (LC) is one of the representative diseases which can be complicated with secondary sarcopenia. Muscle mass loss becomes more pronounced with worsening liver reserve in LC patients. While frailty encompasses a state of increased vulnerability to environmental factors, there is also the reversibility of returning to a healthy state with appropriate intervention. Several assessment criteria for sarcopenia and frailty were proposed in recent years. In 2016, the Japan Society of Hepatology created assessment criteria for sarcopenia in liver disease. In Japan, health checkups for frailty in the elderly aged 75 years or more started in April 2020. Both sarcopenia and frailty can be adverse predictors for cirrhotic patients. In this review article, we will summarize the current knowledge of sarcopenia and frailty in LC patients.