Energy expenditure and substrate metabolism in ethanol-induced liver cirrhosis

Sarcopenia in Chronic Liver Disease: A Metabolic Perspective

Sarcopenia, a condition of low muscle mass, quality, and strength, is commonly found in patients with chronic liver disease (CLD) and is associated with adverse clinical outcomes including reduction in quality of life, increased mortality, and complications. A major contributor to sarcopenia in CLD is the imbalance in muscle protein turnover wherein changes in various metabolic factors such as hyperammonemia, amino acid deprivation, hormonal imbalance, gut dysbiosis, insulin resistance, chronic inflammation, etc. have important roles. In particular, hyperammonemia is a key mediator of the liver-gut axis and is known to contribute to sarcopenia by various mechanisms including increased expression of myostatin, increased phosphorylation of eukaryotic initiation factor 2a, cataplerosis of α-ketoglutarate, mitochondrial dysfunction, increased reactive oxygen species that decrease protein synthesis and increased autophagy-mediated proteolysis. Skeletal muscle is a major organ of insulin-induced glucose metabolism, and sarcopenia is closely linked to insulin resistance and metabolic syndrome. Patients with liver cirrhosis are in a hypermetabolic state that is associated with catabolism and depletion of amino acids, particularly branched-chain amino acids. Sarcopenia can have significant implications for nonalcoholic fatty liver disease, the most common form of CLD worldwide, because of the close link between metabolic syndrome and sarcopenia. This review discusses the potential metabolic derangement as a cause or effect of sarcopenia in CLD, as well as interorgan crosstalk, which that might help identifying a novel therapeutic strategies.

Hepatogenous diabetes: Knowledge, evidence, and skepticism

The diabetogenic potential of liver cirrhosis (LC) has been known for a long time, and the name "hepatogenous diabetes" (HD) was coined in 1906 to define the condition. Diabetes mellitus (DM) that develops as a consequence of LC is referred to as HD. In patients with LC, the prevalence rates of HD have been reported to vary from 21% to 57%. The pathophysiological basis of HD seems to involve insulin resistance (IR) and pancreatic β-cell dysfunction. The neurohormonal changes, endotoxemia, and chronic inflammation of LC initially create IR; however, the toxic effects eventually lead to β-cell dysfunction, which marks the transition from impaired glucose tolerance to HD. In addition, a number of factors, including sarcopenia, sarcopenic obesity, gut dysbiosis, and hyperammonemia, have recently been linked to impaired glucose metabolism in LC. DM is associated with complications and poor outcomes in patients with LC, although the individual impact of each type 2 DM and HD is unknown due to a lack of categorization of diabetes in most published research. In fact, there is much skepticism within scientific organizations over the recognition of HD as a separate disease and a consequence of LC. Currently, T2DM and HD are being treated in a similar manner although no standardized guidelines are available. The different pathophysiological basis of HD may have an impact on treatment options. This review article discusses the existence of HD as a distinct entity with high prevalence rates, a strong pathophysiological basis, clinical and therapeutic implications, as well as widespread skepticism and knowledge gaps.

Assessment of resting energy expenditure in patients with cirrhosis

BACKGROUND

Malnutrition affects 20% to 50% of patients with cirrhosis. It may be associated with serious complications and has a direct impact on prognosis. Resting energy expenditure (REE) is an important parameter to guide the optimization of therapy and recovery of nutritional status in patients with cirrhosis. However, the REE of patients with cirrhosis is still unclear, casting doubt upon the optimal nutritional management approach.

AIM

To identify the best method that predicts the REE of cirrhotic patients, using indirect calorimetry (IC) as the gold standard.

METHODS

An observational study was performed on 90 patients with cirrhosis. REE was assessed by IC, bioelectrical impedance analysis (BIA), and predictive formulas, which were compared using Bland-Altman plots and the Student’s t-test.

RESULTS

REE values measured by IC (1607.72 ± 257.4 kcal) differed significantly from those determined by all other methods (BIA: 1790.48 ± 352.1 kcal; Harris & Benedict equation: 2373.54 ± 254.9 kcal; IOM equation: 1648.95 ± 185.6 kcal; Cunningham equation: 1764.29 ± 246.2 kcal), except the Food and Agriculture Organization of the United Nations, World Health Organization, and United Nations University (FAO/WHO/UNU) (1616.07 ± 214.6 kcal) and McArdle (1611.30 ± 241.8 kcal) equations. We found no significant association when comparing IC and 24-h dietary recall among different Child-Pugh classes of cirrhosis.

CONCLUSION

The IOM and FAO/WHO/UNU equations have the best agreement with the CI. These results indicate a possibility of different tools for the clinical practice on cirrhotic patients.

ESPEN guideline on clinical nutrition in liver disease

This update of evidence-based guidelines (GL) aims to translate current evidence and expert opinion into recommendations for multidisciplinary teams responsible for the optimal nutritional and metabolic management of adult patients with liver disease. The GL was commissioned and financially supported by ESPEN. Members of the guideline group were selected by ESPEN. We searched for meta-analyses, systematic reviews and single clinical trials based on clinical questions according to the PICO format. The evidence was evaluated and used to develop clinical recommendations implementing the SIGN method. A total of 85 recommendations were made for the nutritional and metabolic management of patients with acute liver failure, severe alcoholic steatohepatitis, non-alcoholic fatty liver disease, liver cirrhosis, liver surgery and transplantation as well as nutrition associated liver injury distinct from fatty liver disease. The recommendations are preceded by statements covering current knowledge of the underlying pathophysiology and pathobiochemistry as well as pertinent methods for the assessment of nutritional status and body composition.

Pre-Transplant Aerobic Capacity and Prolonged Hospitalization After Liver Transplantation

Introduction

Patients with end stage liver disease (ESLD) referred for liver transplantation (LT) are forwarded to pulmonary evaluation before being operated. ESLD is associated with muscle wasting, reduced exercise tolerance and aerobic capacity.

Objectives

We assessed the association between aerobic capacity (AC), liver disease severity and postoperative LT outcomes in a series of LT candidates in a university affiliated hospital in Brazil.

Methods

Pre-LT oxygen uptake at peak (pre-VO_2peak), liver disease severity, and early pos-LT outcomes such as length of intensive care unit (ICU) stay, <5 and ≥5 days and hospitalization, <20 and ≥20 days and postoperative mortality were compared. Pre-VO_2peak was measured through the cardiopulmonary exercise testing (CPET). Severity of liver disease was estimated by the Model for End-Stage Liver Disease (MELD) categorization into MELD < 18 and MELD ≥ 18 groups. Student's t-test was used to compare these groups. A logistic regression model was built to verify the effect of those variables on the length of ICU stay, length of hospitalization and postoperative mortality.

Results

A total of 47 patients were include in analysis. Pre-VO_2peak was similar to that of healthy sedentary individuals (75 ± 18%) and worse in the MELD ≥ 18 group as compared to the MELD < 18 group (19.51 ± 7.87 vs 25.21 ± 8.76 mL/kg/min, respectively; p = 0.048). According to the multivariate analysis, only a lower pre-VO_2peak (<20.09 ± 4.83 mL/kg/min) was associated to a greater length of hospitalization (p = 0.01).

Conclusions

In LT candidates, a reduced pre-VO_2peak may predict a higher risk of greater pos-LT length of hospitalization. The length of ICU stay and postoperative mortality were not associated with variables studied. This finding should be evaluated in other studies before making specific recommendations about a routine use of CPET in LT candidates.

Sarcopenia and a physiologically low respiratory quotient in patients with cirrhosis: a prospective controlled study

Patients with cirrhosis have increased gluconeogenesis and fatty acid oxidation that may contribute to a low respiratory quotient (RQ), and this may be linked to sarcopenia and metabolic decompensation when these patients are hospitalized. Therefore, we conducted a prospective study to measure RQ and its impact on skeletal muscle mass, survival, and related complications in hospitalized cirrhotic patients. Fasting RQ and resting energy expenditure (REE) were determined by indirect calorimetry in cirrhotic patients (n = 25), and age, sex, and weight-matched healthy controls (n = 25). Abdominal muscle area was quantified by computed tomography scanning. In cirrhotic patients we also examined the impact of RQ on mortality, repeat hospitalizations, and liver transplantation. Mean RQ in patients with cirrhosis (0.63 ± 0.05) was significantly lower (P < 0.0001) than healthy matched controls (0.84 ± 0.06). Psoas muscle area in cirrhosis (24.0 ± 6.6 cm(2)) was significantly (P < 0.001) lower than in controls (35.9 ± 9.5 cm(2)). RQ correlated with the reduction in psoas muscle area (r(2) = 0.41; P = 0.01). However, in patients with cirrhosis a reduced RQ did not predict short-term survival or risk of developing complications. When REE was normalized to psoas area, energy expenditure was significantly higher (P < 0.001) in patients with cirrhosis (66.7 ± 17.8 kcal/cm(2)) compared with controls (47.7 ± 7.9 kcal/cm(2)). We conclude that hospitalized patients with cirrhosis have RQs well below the traditional lowest physiological value of 0.69, and this metabolic state is accompanied by reduced skeletal muscle area. Although low RQ does not predict short-term mortality in these patients, it may reflect a decompensated metabolic state that requires careful nutritional management with appropriate consideration for preservation of skeletal muscle mass.

Resting energy expenditure and substrate metabolism in Chinese patients with acute or chronic hepatitis B or liver cirrhosis

OBJECTIVE

Patients with liver disease usually have an imbalanced nutrient and energy metabolism that leads to malnutrition and seriously affects their prognosis. Therefore, it is of great clinical interest to understand the resting energy expenditure (REE) and oxidation rates of glucose, fat, and protein in these patients.

METHODS

A total of 315 patients with liver diseases caused by hepatitis B virus were categorized into three groups: 20 acute hepatitis patients, 142 chronic hepatitis patients and 153 liver cirrhosis patients. The REE and the oxidation rates of glucose, fat and protein were assessed by indirect heat measurement. Energy intake data were also collected which were compared with the REE results.

RESULTS

The REE per kg (REE/kg) were 27.34 ± 5.46 kJ/kg, 21.67 ± 5.01 kJ/kg and 19.07 ± 4.45 kJ/kg in acute, chronic hepatitis and liver cirrhosis patients (p=0.000), respectively. Respiratory quotient (RQ) tended to be lower in patients with chronic hepatitis and liver cirrhosis than that in acute hepatitis patients (p=0.023). Energy, protein and carbohydrate intakes were lower in liver cirrhosis patients.

CONCLUSION

These data demonstrated that Chinese patients with chronic hepatitis B and liver cirrhosis had lower energy expenditure and abnormal substrate metabolism. Patients with chronic hepatitis and cirrhosis had a higher protein oxidation rate and a lower carbohydrate oxidation rate compared with acute hepatitis patients.

Insulin resistance in liver cirrhosis. Positron-emission tomography scan analysis of skeletal muscle glucose metabolism

BACKGROUND

Insulin resistance and glucose intolerance are a major feature of patients with liver cirrhosis. However, site and mechanism of insulin resistance in cirrhosis are unknown. We investigated insulin-induced glucose metabolism of skeletal muscle by positron-emission tomography to identify possible defects of muscle glucose metabolism in these patients.

METHODS

Whole body glucose disposal and oxidation were determined by the combined use of the euglycemic-hyperinsulinemic clamp technique (insulin infusion rate: 1 mU/kg body wt per min) and indirect calorimetry in seven patients with biopsy-proven liver cirrhosis (Child: 1A, 5B, and 1C) and five healthy volunteers. Muscle glucose uptake of the thighs was measured simultaneously by dynamic [18F]fluorodeoxyglucose positron-emission tomography scan.

RESULTS

Both whole body and nonoxidative glucose disposal were significantly reduced in patients with liver cirrhosis (by 48%, P < 0.001, and 79%, P < 0.0001, respectively), whereas glucose oxidation and the increase in plasma lactate were normal. Concomitantly, skeletal muscle glucose uptake was reduced by 69% in liver cirrhosis (P < 0.003) and explained 55 or 92% of whole body glucose disposal in cirrhotics and controls, respectively. Analysis of kinetic constants using a three-compartment model further indicated reduced glucose transport (P < 0.05) but unchanged phosphorylation of glucose in patients with liver cirrhosis.

CONCLUSIONS

Patients with liver cirrhosis show significant insulin resistance that is characterized by both decreased glucose transport and decreased nonoxidative glucose metabolism in skeletal muscle.

Metabolic responses to lipid infusions in patients with liver cirrhosis

Energy expenditure, whole body substrate oxidation rates and arterial substrate concentrations were measured in 14 patients with liver cirrhosis and 13 control subjects before and during sequential infusions of a long chain (LCT) or a medium chain triglyceride emulsion (MCT) without and with concomitant insulin plus glucose infusions. Resting energy expenditure, basal substrate oxidation rates and the arterial concentrations of glucose, lactate, triglycerides and ketones were normal, whereas plasma free fatty acids and glycerol were both increased in patients with liver cirrhosis. The arterial plasma triglyceride and free fatty acid concentrations as well as whole body lipid oxidation rate rose in response to LCT in both groups and the maximum lipid oxidation rate was 1.1 or 1.3 mg/kg fat free mass x min in controls and in cirrhotics, respectively (n.s.). Concomitantly, glucose oxidation rate fell to 65% of basal values in controls (p < 0.01), but remained nearly unchanged in the cirrhotic group (89% of the basal value; n.s.). The increase in plasma ketones was reduced to 67% of control values in liver cirrhosis (p < 0.01). Only a slight effect on energy expenditure was observed in both groups. When compared to controls, liver cirrhosis impaired insulin-induced increases in glucose disposal (-30%, p < 0.01) and in non oxidative glucose metabolism (-93%, p < 0.01). Concomitantly, normal increases in energy expenditure, glucose oxidation rate and the arterial plasma lactate concentrations and normal decreases in lipolysis, lipid oxidation and ketogenesis were observed in patients with liver cirrhosis. When lipids were given together with glucose, energy expenditure and lipid oxidation increased in controls, but glucose was the preferred fuel oxidised and lipid-induced thermogenesis was reduced in the cirrhotic group. Using a 50% MCT-emulsion, plasma free fatty acid concentrations further increased, but energy expenditure and lipid oxidation remained unchanged in both groups and further increases in plasma ketones were only observed in controls. Infusing glycerol in a subgroup of patients showed no thermogenic effect and a reduced glycerol clearance in liver cirrhosis.

Protein-calorie malnutrition in liver cirrhosis

The purpose of this article is to present detailed data on the nutritional assessment in cirrhotic patients. The exact frequency and types of malnutrition, its associations with the aetiology of liver disease, liver dysfunction and clinical staging in liver cirrhosis are unknown. A new classification system is presented which may help to suggest some interventional guidelines. Physical (anthropometry, 24-h urinary creatinine excretion, bioelectrical impedance analysis (BIA), total body potassium counting, ultrasound examination) and metabolic (indirect calorimetry) assessment of nutritional status was therefore performed in 123 patients with liver cirrhosis, who were considered as potential candidates for liver transplantation. Data were related to the clinical, biochemical, histological and prognostic data of liver disease. Of our patients 65% showed some signs of protein-calorie malnutrition as indicated by low body cell mass, reduced serum albumin concentrations or abnormal skinfold thickness. Of these 34% were considered as "kwashiorkor-like" (normal body composition, serum albumin less than 35 g/l), and 18% were "marastic" (reduced body weight, body cell mass, and fat mass). However, 49% of the malnourished group had reduced body cell mass in association with increased fat mass and frequently presented with a normal body weight ("mixed" or "obese" type). Protein-calorie malnutrition did not correlate with the aetiology of the disease and biochemical parameters of liver function. Malnutrition was observed at all clinical stages but was more frequently seen at advanced stages. We conclude that malnutrition associated with liver cirrhosis is not a clear phenomenon. Its clinical presentation is heterogenous and not reflected by the histological or biochemical parameters of liver disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Pathophysiology and clinical basis of prevention and treatment of complications of chronic liver disease

Chronic liver failure is characterized by the appearance of jaundice, ascites, encephalopathy and/or gastrointestinal bleeding. Acute episodes of hepatic decompensation are frequently precipitated by additional events, e.g. septicaemia, diuretic therapy or excessive protein intake. Identification, correction and treatment of these precipitating factors are first steps in the management of chronic liver failure. Nutritional support is important in the treatment of cirrhotic patients, because malnutrition is one of the major determinants of patient outcome. Management of encephalopathy reduces the appearance of gut-derived nitrogenous toxins and corrects imbalances in amino acid metabolism. Treatment of ascites is salt restriction supported by gentle and incremental administration of diuretics. Ursodesoxycholic acid has become a new and promising modality in the management of cholestatic liver diseases. If conservative therapy fails to recompensate liver function, liver transplantation may be indicated.