Sarcopenia (severe muscle depletion) is a prevalent muscle abnormality in patients with cirrhosis that confers poor prognosis both pre- and post-liver transplantation. The pathogenesis of sarcopenia is multifactorial and results from an imbalance between protein synthesis and breakdown. Nutritional, metabolic, and biochemical abnormalities seen in chronic liver disease alter whole body protein homeostasis. Hyperammonemia, increased autophagy, proteasomal activity, lower protein synthesis, and impaired mitochondrial function play an important role in muscle depletion in cirrhosis. Factors including cellular energy status, availability of metabolic substrates (e.g., branched-chain amino acids), alterations in the endocrine system (insulin resistance, circulating levels of insulin, insulin-like growth factor-1, corticosteroids, and testosterone), cytokines, myostatin, and exercise are involved in regulating muscle mass. A favored atrophy of type II fast-twitch glycolytic fibers seems to occur in patients with cirrhosis and sarcopenia. Identification of muscle biological abnormalities and underlying mechanisms is required to plan clinical trials to reverse sarcopenia through modulation of specific mechanisms. Accordingly, a combination of nutritional, physical, and pharmacological interventions might be necessary to reverse sarcopenia in cirrhosis. Moderate exercise should be combined with appropriate energy and protein intake, in accordance with clinical guidelines. Interventions with branched chain amino acids, testosterone, carnitine, or ammonia-lowering therapies should be considered individually. Various factors such as dose, type, duration of supplementations, etiology of cirrhosis, amount of dietary protein intake, and compliance with supplementation and exercise should be the focus of future large randomized controlled trials investigating both prevention and treatment of sarcopenia in this patient population.

Summary: Background: Sarcopenia is associated with both increased wait‐list mortality and mortality following liver transplantation.Aims: To determine the course of sarcopenia from transplant evaluation until 1 year post‐transplant, and its implications on hospitalisation and mortality following liver transplantation.Methods: Two hundred and ninety‐three transplant recipients from 2002 to 2006 had pre‐transplant CT scans analysed at the third lumbar region for sarcopenia, myosteatosis and abdominal visceral fat content. Half the recipients had post‐transplant CT scan for interpretation (161/293).Results: Sarcopenia was present in 146/293 (50%) of the patients pre‐transplant. There was a significant decrease in muscle mass (loss 2.0 ± 4.9 cm²/m²; P < 0.001), and an increase in myosteatosis while awaiting liver transplantation. There was no significant change in abdominal visceral fat. For every 1 cm²/m² decrease in muscle mass there was an increase in post‐transplant length of stay by 0.36 days (P = 0.005). Post‐transplant, 98/161 (61%) of patients with CT imaging had sarcopenia (25 de novo and 73 persistent), with continued increase in myosteatosis, lower Hounsfield units (−5.0 [IQR −8.6 to 0.1]; P < 0.001) and an increase in abdominal visceral fat (4.9 [IQR −4.4 to 15.6] cm²/m²; P < 0.001). There was no statistically significant difference in 1‐year mortality in patients with de novo sarcopenia compared to patients with sarcopenia both pre‐ and post‐transplant (HR 1.88; P = 0.088).Conclusions: Sarcopenia progresses up to 1 year following liver transplantation and is associated with an increase in post‐transplant length of stay.

Myosteatosis, or pathological excess fat accumulation in muscle, has been widely defined as a lower mean skeletal muscle radiodensity on computed tomography (CT). It is reported in more than half of patients with cirrhosis, and preliminary studies have shown a possible association with reduced survival and increased risk of portal hypertension complications. Despite the clinical implications in cirrhosis, a standardized definition for myosteatosis has not yet been established. Currently, little data exist on the mechanisms by which excess lipid accumulates within the muscle in individuals with cirrhosis. Hyperammonemia may play an important role in the pathophysiology of myosteatosis in this setting. Insulin resistance, impaired mitochondrial oxidative phosphorylation, diminished lipid oxidation in muscle and age-related differentiation of muscle stem cells into adipocytes have been also been suggested as potential mechanisms contributing to myosteatosis. The metabolic consequence of ammonia-lowering treatments and omega-3 polyunsaturated fatty acids in reversing myosteatosis in cirrhosis remains uncertain. Factors including the population of interest, design and sample size, single/combined treatment, dosing and duration of treatment are important considerations for future trials aiming to prevent or treat myosteatosis in individuals with cirrhosis.

Summary: Background: Recent advances in evaluation of body composition show body mass index to be inadequate in differentiating between body compartments in cirrhosis. Given the limitations of body mass index, body composition evaluation using computed tomography has been increasingly used as a non‐invasive clinical tool with prognostic value. Another factor influencing prognosis includes sex‐specific differences in body composition that are seen in cirrhosis.Aim: To review current knowledge regarding the frequency and clinical implications of abnormal body composition features in cirrhosis.Methods: We searched PubMed database and limited the literature search to full‐text papers published in English. Studies using inappropriate landmarks or demarcation of body composition components on computed tomography images were eliminated.Results: Sarcopenia is a well established factor affecting morbidity and mortality in cirrhosis. Other important body composition components that have been overlooked thus far include subcutaneous adipose tissue and visceral adipose tissue. Female patients with cirrhosis and low subcutaneous adiposity have a higher risk of mortality, whereas male patients with high visceral adiposity have a higher risk of hepatocellular carcinoma and recurrence following liver transplantation. Increased adipose tissue radiodensity has been associated with risk of decompensation and mortality.Conclusions: Further evaluation of body composition abnormalities may help with development of targeted therapeutic strategies and improve outcome in patients with cirrhosis. Moreover, recognition of these abnormalities could improve prioritisation for liver transplantation as our current method based solely on liver function might lead to risk misclassification.