Nutritional Support in Chronic Liver Disease

Anne S Henkel; Alan L Buchman

Disclosures

Nat Clin Pract Gastroenterol Hepatol. 2006;3(4):202-209. 

In This Article

Nutritional Assessment

Considering the complications created by malnutrition, a thorough nutritional assessment should be performed for every patient with chronic liver disease. This, however, might not be easily accomplished.

There are several factors that complicate the evaluation of nutritional status in patients with cirrhosis. Many of the commonly used markers of malnutrition are not useful parameters for the prediction of malnutrition in this patient population. Weight, for example, is not a reliable indicator of malnutrition, because the presence of ascites and edema will increase the measured weight, whereas lean body mass might actually be reduced. Also, many of the laboratory tests that are typical markers of nutritional status are less reliable in patients with cirrhosis. For example, concentrations of albumin and prealbumin could be low because of low levels of synthesis, rather than because of poor nutritional status. Other parameters must be used in the evaluation of these patients. A commonly used method is anthropometry. Anthropometric measurements include triceps skin-fold thickness and midarm circumference, which assess fat storage and skeletal muscle mass, respectively. This method is, however, also not without its problems. Potential limitations of anthropometry include poor interobserver reproducibility and overestimation of these values because of the THIRD-SPACING of fluid.[11]

Subjective global assessment (SGA) is a technique that combines multiple elements of nutritional assessment to classify the severity of malnutrition.[37] These components are weight loss during the previous 6 months, changes in dietary intake, gastrointestinal symptoms, functional capacity, metabolic demands, signs of muscle wasting, and the presence of presacral or pedal edema. SGA has been shown to have an interobserver reproducibility rate of 80%,[38] and is useful in predicting outcome following liver transplantation.[3]

The assessment of muscle function measuring hand-grip strength and respiratory-muscle strength has also been used in nutritional evaluation; however, these measurements tend to be more useful when taken serially.[39] Hand-grip strength is a highly sensitive test and might actually overestimate the prevalence of malnutrition. Nonetheless, hand-grip strength seems to be a good predictor of complications in patients with advanced liver disease. A recent study compared SGA, the prognostic nutritional index, and hand-grip strength as predictors of outcome in patients with cirrhosis.[40] In this study, decreased hand-grip strength accurately predicted a poor clinical outcome that was related to a higher rate of complications, including ascites, hepatic encephalopathy, spontaneous bacterial peritonitis, and hepatorenal syndrome, whereas SGA and the prognostic nutritional index did not. The prevalence of malnutrition was highest when measured by hand-grip strength, suggesting that hand-grip strength could be the most sensitive technique. Figueiredo et al. showed that decreased handgrip strength before transplantation is associated with longer stays in the intensive-care unit and more postoperative infections.[17]

Depletion of body cell mass (BCM) is a useful estimation of nutritional status.[41] Decreased BCM before transplantation has been shown to correlate with a threefold increase in post-transplant mortality rates.[5,6] ISOTOPE DILUTION, measurement of WHOLE-BODY POTASSIUM, and in vivo neutron activation analysis are arguably the most accurate methods currently available to assess body composition; however, these techniques are costly and labor intensive, making them less practical for routine nutritional screening. BIOELECTRICAL IMPEDANCE is a more readily available tool for estimating BCM. Although this is a reliable tool in many patient populations, the accuracy of these measurements in patients with cirrhosis can be affected by fluid retention.[42] Pirlich et al., however, showed that estimation of BCM using bioelectrical impedance correlated closely with BCM measured by total body potassium in patients with and without ascites.[43] Figueiredo et al. studied whether the traditionally measured nutritional parameters correlate with BCM. Although depleted BCM correlated most closely with arm-muscle circumference and hand-grip strength, most parameters, nonetheless, did not correlate well with depleted BCM.[44]

An evaluation of the status of energy metabolism might be a reasonable component of a nutritional assessment, because there seems to be a correlation between hypermetabolism and malnutrition.[6,31] This evaluation can be accomplished using indirect calorimetry, a widely accepted tool that is used to estimate REE. Indirect calorimetry measures the consumption of oxygen and production of carbon dioxide, and REE is calculated using the Weir equation: [kcal/d = [3.941 × VO2(l/day)] + 1.106 × VCO2(l/day)].[45] The measured REE is compared with the predicted energy expenditure, as calculated using the Harris-Benedict equation.[46] A patient is generally considered to be hypermetabolic if the measured REE is more than 10-20% greater than the predicted REE.[30,31] In transplant recipients, hypermetabolism is associated with a decreased survival rate after transplantation.[5] The use of indirect calorimetry enables the calculation of the nonprotein respiratory quotient, defined as the ratio of energy produced by carbohydrate metabolism to energy generated by fat oxidation, which confirms whether a patient has an altered pattern of fuel consumption.

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