Sarcopenia in end-stage liver disease and after liver transplantation

Sarcopenia occurs in 30-70% of patients with end-stage liver disease and is associated with inferior pre- and post-liver transplant outcomes such as prolonged intubation times, long intensive care and hospitalization times, heightened risk of post-transplant infection, reduced health-related quality of life, and increased rates of mortality. The pathogenesis of sarcopenia is multifactorial and involves biochemical disturbances such as hyperammonemia, low serum concentrations of branched-chain amino acids (BCAAs) and low serum levels of testosterone, as well as chronic inflammation, inadequate nutritional status, and physical inactivity. Prompt recognition and accurate assessment of sarcopenia are critical and require imaging, dynamometry, and physical performance testing for the assessment of its subcomponents: muscle mass, muscle strength, and muscle function, respectively. Liver transplantation mostly fails to reverse sarcopenia in sarcopenic patients. In fact, some patients develop de novo sarcopenia after undergoing liver transplantation. The recommended treatment of sarcopenia is multimodal and includes a combination of exercise therapy and complementary nutritional interventions. Additionally, new pharmacological agents (e.g. myostatin inhibitors, testosterone supplements, and ammonia-lowering therapy) are under investigation in preclinical studies. Here, we present a narrative review of the definition, assessment, and management of sarcopenia in patients with end-stage liver disease prior to and after liver transplantation.