Journal of Parenteral and Enteral Nutrition

Anthropometry is a technique in which simple measuring instruments are used to describe human form. By applying the measurement directly or through use of additional calculations, the practitioner can partition the body into fat and fat-free components. Quantifying these two body spaces provides information on the amount and rate of change over time in whole body energy supply and protein mass. These data can then be used in association with other indices of energy and protein metabolism. Whereas anthropometry is simple, practical, and inexpensive, the technique is limited to a qualitative tool by several sources of error. A thorough understanding of the strengths, limitations, and appropriate applications of anthropometry is essential when applying the method in clinical practice. (Journal of Parenteral and Enteral Nutrition 11:36S-41S,1987)

The measurement of body composition by multiple isotope dilution provides an accurate and precise measure of both the nutritional state and the response to nutritional support. A multiple isotope dilution technique has been developed that permits measurement of the three major components of body composition: body fat, extracellular mass (ECM), and body cell mass (BCM). Normal body composition was defined by data obtained in 25 healthy volunteers. Malnutrition is characterized by a loss of BCM and an expansion of the ECM, and as a result the lean body mass is not significantly different from normal. The loss of body weight with malnutrition therefore often reflects the loss of body fat. The utility of body composition measurements was demonstrated by determining the effect of total parenteral nutrition on body composition to determine the relationship between caloric intake and the change in the BCM. A statistically significant relationship was developed which demonstrated that a caloric intake in the range of 30-40 cal/kg/day is required for maintenance. To restore a depleted or malnourished BCM requires a caloric intake in excess of that required for maintenance. The measurement of body composition by multiple isotope dilution is complex and time consuming, and requires specialized laboratory facilities and specially trained personnel. As a result, these measurements are not suited for routine patient management, but should rather be reserved for research purposes. (Journal of Parenteral and Enteral Nutrition 11:42S-47S, 1987)

Whole body nitrogen can be measured by neutron activation analysis with an acceptable radiation dose; it is an index of body protein which, in normal subjects, is 65% cellular protein and 35% extracellular connective collagen. Whole body potassium can be measured by whole body counting without irradiating the subject; it is an index of body cell mass.

We measured whole body nitrogen, potassium, extracellular water, intracellular water, and fat-folds. The differences between 37 malnourished patients and five normal subjects suggested that the patients had 9 kg less cell mass than normal, but no difference in extracellular mass. Measurements were made on eight patients before and after 14 days of total parenteral nutrition; balance of nitrogen intake and excretion also was measured. The changes were consistent with mean increases of 3 kg of cellular mass and 3 kg of fat with no change of extracellular mass.

The accuracy and sensitivity of the whole body measurements need further confirmation for use in patients with changing body composition. Where tissue wasting is largely from the cellular compartment, potassium could be a more sensitive index of wasting than nitrogen. Multielement analysis of nitrogen, potassium, chlorine, and carbon will probably be valuable in elucidating body composition in malnutrition. (Journal of Parenteral and Enteral Nutrition11:48S-50S, 1987)

Nutritional inadequacies profoundly affect the content and distribution of water and electrolytes in muscle tissue. However, most changes in tissue water and electrolytes are nonspecific and reflect the degree of sickness; they cannot be used for evaluation of malnutrition, except to indicate whether there is a loss or excess of intracellular ions, such as potassium and magnesium. In patients without disturbances in potassium metabolism, muscle cell potassium and protein are strongly correlated, but this relationship does not hold true in patients with potassium depletion. Accumulation and loss of potassium occur in parallel with changes in muscle glycogen, independent of other muscle constituents, eg, magnesium. Potassium depletion and excess, as well as changes in muscle glycogen, must be considered when evaluating the relation of lean body mass and total body protein content to total body potassium. (Journal of Parenteral and Enteral Nutrition 11:51S-54S, 1987)

Four relatively new techniques that apply electromagnetic or sound waves promise to play a major role in the study of human body composition and in clinical nutritional assessment. Computerized axial tomography, nuclear magnetic resonance, infrared interactance, and ultrasonography provide capabilities for measuring the following: total body and regional fat volume; regional skeletal muscle volume; brain, liver, kidney, heart, spleen, and tumor volume; lean tissue content of triglyceride, iron, and high-energy intermediates; bone density; and cardiac function. Each method is reviewed with regard to basic principles, research and clinical applications, strengths, and limitations. (Journal of Parenteral and Enteral Nutrition 11:64S-69S,1987)

Theoretically, a large number of tests of immunologic functions could be used for nutritional assessment. However, many of these immunologic tests require specialized laboratory skills and take a long time to perform. These tests provide little additional information to the clinician concerning the nutritional status of the patient, compared to the data that can be obtained from a few simple, selected immunologic measurements. Only a few immunologic tests are sufficiently simple, reproducible, and reliable indicators of nutritional status to be of practical value for routine nutritional assessment. These are the total lymphocyte count and skin tests. At present, all of the other immunologic measurements that have been reviewed should be considered as research tools for nutritional assessment. Immunological tests can be affected by many clinical variables unrelated to nutrition, such as specific pathologic conditions, immunodepressive therapies, accidental or surgical trauma, and infection, and this fact should be considered when using immunological tests to assess nutritional status. Malnutrition suppresses the acute-phase response of plasma proteins. The measurement of the acute-phase response of selected acute-phase proteins can be a functional measurement of nutritional status. (Journal of Parenteral and Enteral Nutrition 11:70S-72S, 1987)

The use of the creatinine height index (CHI) as a measure of protein nutrition is reviewed. Any such cross-sectional measurement is inherently limited. Using published values for urinary creatinine excretion per kilogram body weight in adult subjects of varying age and values for "ideal" weight as a function of height, we have derived normal values for expected creatinine excretion in men and women of varying height. These permit the derivation of an age-corrected CHI. Possible explanations for the normal decrease in creatinine excretion with age include (1) decreasing lean body mass with age, (2) decreasing proportion of muscle in lean body, and (3) lower meat intake in older persons. Diet has an important influence if meat intake is substantial of if consumption of a creatine-free diet is prolonged. Creatinine metabolism and extrarenal excretion are minor, except in subjects with reduced renal function. Application of a correction for constant extra-renal clearance of creatinine in patients with chronic renal failure probably is not valid. Further observations of creatinine excretion in normal subjects of varying age and height are needed. (Journal of Parenteral and Enteral Nutrition 11:73S-78S, 1987)

Classical balance techniques are a powerful, sensitive, and usually accurate technique for assessing the nutritional or metabolic response to changes in nutritional intake or to metabolic or physiological perturbations. Balances are particularly sensitive for examining transient or short-term responses to nutritional or metabolic stimuli. A major factor responsible for the precision and sensitivity of this technique is the precise control of the activities and environment of an individual during a classical metabolic balance study (eg, the carefully defined dietary intake, degree of exercise, and environmental temperature to prevent sweating); these same factors may enhance the precision and sensitivity of other metabolic or nutritional investigations that may be carried out concurrently with a balance study. Finally, for nitrogen balance studies, the measurement of nitrogen (eg, by the Kjeldahl technique) can be very accurate and sensitive.

Despite these advantages, there are important limitations and errors that are inherent in the balance technique. The errors tend to overestimate intake and underestimate output, thereby leading to erroneously positive balances. These errors include losses of food on cooking and eating utensils and dishware, losses of feces or urine on toilet paper or in collection containers, and losses through sweat, exfoliated skin, hair and nail growth, saliva, menses, blood sampling, toothbrushing, semen, and, for nitrogen, from flatus and respiration. Cumulative balance measurements are particularly likely to be falsely positive. The magnitude of unmeasured losses vary among healthy individuals, with the magnitude of the nitrogen intake (for nitrogen), in altered environmental conditions (eg, with sweating), and possibly in disease states. Balance studies are also expensive and time consuming. Finally, the fate and intermediary metabolism of the compounds ingested or infused into the subject and the sources of the output of nitrogen or minerals are poorly defined by the balance technique. Balances are probably most helpful when they are performed in conjunction with other techniques for studying nutrition or metabolism, when the intake is not too high (eg, equal to or less than 12-15 g/day for nitrogen), and when the same individual is studied before and after a perturbation in their nutritional or metabolic status. Classical balance techniques are so complicated and expensive that they are primarily of value for research studies. (Journal of Parenteral and Enteral Nutrition 11:79S-85S, 1987)

Indirect calorimetry with the ventilated-hood open circuit is a useful and accurate technique to measure energy expenditure in acutely ill patients. This approach should be useful to evaluate the energy and the nutrient needs of a patient under acute conditions. The measurement of energy expenditure is of obvious importance in assessing protein-calorie malnutrition. A better understanding of energy balance and nitrogen balance in critically ill patients is needed to determine the best caloric and nutrient intake to avoid tissue depletion. It is foreseen that this method will become more widely used when reliable equipment is made available. (Journal of Parenteral and Enteral Nutrition11:86S-89S, 1987)

The measurement of gas exchange for use in indirect calorimetry is a clinical research tool struggling to find its proper place in the care of acutely ill and nutritionally depleted patients. Some investigators have proposed that it should be used as part of the nutritional assessment. Unfortunately, in common with many other measurements for nutritional assessment, the information provided must be integrated with other information. It is recognized that factors other than malnutrition may influence the level of the metabolic rate. Despite the lack of precision and specificity, the measurement of energy expenditure provides an important reference for determining patients' requirements for energy intake. As with many other procedures in clinical medicine, the more severely ill the patient, the less the accuracy of standard formulas for estimating energy expenditure. Thus, actual measurements of energy expenditure assume special value. (Journal of Parenteral and Enteral Nutrition11:90S-94S, 1987)

Protein synthesis and degradation are particularly sensitive to malnutrition and catabolic states. Intracellular protein degradation is determined by the conformation, molecular weight, isoelectric point, and carbohydrate content of the proteins. ATP-stimulated endoproteases appear to catalyse the rate-limiting steps. In the liver, proteolysis is reduced by amino acids and/or insulin, whereas glucagon stimulates protein degradation, probably due to depletion of intracellular gluconeogenic amino acids. In the muscle, protein degradation is promoted by interleukin-1 and inhibited by Ep-475, which specifically inactivates cathepsin B,H, and L. Myofibrillar alkaline protemase activity increases postoperatively and in patients suffering from malignant tumors, whereas normal proteinase values were observed in these patients following total parenteral nutrition. Increased alkaline proteinase activity is also observed in diabetes mellitus and is normalized by insulin. Extracellular proteolysis has been reported in patients with hypercatabolic acute renal failure and in patients with sepsis or acute pancreatitis. Plasma fractions obtained from hypercatabolic patients with postoperative acute renal failure were proteolytic. Plasma proteinase activity decreases during hemodialysis due to elimination of a metallo-proteinase. Plasma α2-macroglobulin decreases in patients with acute renal failure and also during acute pancreatitis. Proteolytic degradation of parathyroid hormone by sera obtained from patients with acute pancreatitis has been observed. Also, there is a decrease of high molecular weight kininogen during experimental acute pancreatitis. Granulocyte elastase increases postoperatively, mainly in patients with sepsis. Sepsis also causes increased proteolytic activity in the urine.

In conclusion, intracellular protein degradation can supply important precursors for hepatic and renal gluconeogenesis during malnutrition. Selective and nonspecific proteolysis may occur in patients with severe injury, sepsis, or acute renal failure, and result in the consumption of various plasma proteins. (Journal of Parenteral and Enteral Nutrition 11:98S-103S, 1987)

The influence of the clinical condition and the intravenous intake on parameters of fat metabolism has been analyzed. Compared to normal subjects, the correlation between plasma concentrations and the turnover rate of glycerol and free fatty acids varies in the opposite direction in nutritionally depleted and severely injured patients. The significance of plasma concentrations as an index of fat mobilization should be interpreted in relation to the clinical condition. Kinetic measurements are particularly interesting in hypermetabolic patients. Plasma triglyceride and cholesterol concentrations are markedly affected by surgical procedures. Any delay (in treatment) following the injury and the type of intravenous regimen used have an important influence on plasma lipid levels and should be taken into account when groups of patients are studied. The infusion of exogenous fat emulsions significantly affects not only plasma triglyceride levels but also phospholipid and cholesterol concentrations and will modify the plasma lipoprotein pattern. Measurements of plasma clearance and oxidation of fat can be used to evaluate individual tolerance and the metabolic utilization of lipids, but these procedures cannot be easily applied in routine clinical practice. Regular monitoring of plasma triglyceride, cholesterol, and phospholipid concentrations during and after cessation of fat infusion is recommended for each patient who is receiving daily fat infusions so that the safe rate of infusion for that individual can be determined. (Journal of Parenteral and Enteral Nutrition 11:104S-108S, 1987)

The different uses of nutritional assessment are briefly reviewed. The parameters of nutritional assessment should be determined according to the use for which they are intended, such as nutritional epidemiology, preoperative assessment of nutritional risk, or nutritional monitoring during parenteral or enteral feeding. The roles of some nutritional variables that are used to identify and monitor high-risk patients during nutritional repletion are examined. The main questions that confront the clinician are as follows: (1) are the nutritional indicators of surgical risk altered by poor intake of nutrients? (2) can these indicators be normalized with adequate feeding or are they abnormal as a result of the metabolic impact of the disease? (3) are these variables simple indicators of surgical risk or are they directly involved in the host-defense mechanism? The importance is stressed of an integrated assessment of the patient's status when nutritional support is considered. This involves not only the static evaluation of the nutritional support according to standard parameters. but also a prospective and dynamic evaluation of nutrient requirements, length of hospital stay, and the curability of the basic disease. (Journal of Parenteral and Enteral Nutrition 11:115S-121S, 1987)

The prevalence of protein-calorie malnutrition (PCM) and micronutrient deficiency (MND) at the time of admission and discharge from hospital was evaluated in 91 patients consecutively admitted to the Surgery Clinic of the University Hospital of Rome.

Anthropometric parameters and circulating levels of vitamins (A, E, C, B1, and B2) and visceral proteins [retinol-binding protein (RBP, prealbumin (PA), and transferrin] were measured. Twenty-one patients (23%) had moderate to severe PCM, and 70 patients (77%) had normal nutritional status (NNS) at admission. Two patients with PCM died in the hospital. At discharge, the prevalence of PCM was unchanged in the remaining 19 patents. Single or multiple MND was observed initially in 71% of patients with PCM and in 36% with apparently normal nutritional status. Despite vitamin supplementation, MND was present at the time of discharge in 73% of patients with PCM and 44% with NNS.

Nutritional status at the time of admission was assessed in hospitals in six different Italian cities. The criterion for admission to the study was the diagnosis of chronic (>1 yr duration) illness (excluding cancer and multiple organ disorders). Two hundred eighty-four patients (145 males, 139 females), ages 25-88 yr, were selected. The findings indicated a high prevalence of MND (64%). Also, in disorders that usually do not have significant alterations of digestion or absorption, such as uncomplicated cardiorespiratory disease, the prevalence of MND was high (9-38%). The prevalence of MND was not related to body mass index (BMI). PCM was more common among patients with chronic gastrointestinal disease. There was a high level of obesity among cardiac patients (BMI>24-25), even though one-third of them had MND. The prevalence of MND was not related to anthropometric indicators of PCM. (Journal of Parenteral and Enteral Nutrition 11:122S-125S, 1987)

Malnutrition in gastrointestinal disease can result from several pathogenetic mechanisms. The resulting clinical and laboratory features of malnutrition vary according to the specific pathogenetic factors involved. Many of the causes of malnutrition in gastroenterology are similar to those found in other acute and chronic diseases. However, certain disorders, specific to gastroenterology, may alter nutritional indices independent of the usual causes of malnutrition. These include small bowel bacterial overgrowth and protein-losing enteropathy. The impact of these disorders on the indexes of nutritional status is discussed. (Journal of Parenteral and Enteral Nutrition 11:126S-129S, 1987)

A population of 70 patients with liver cirrhosis, most of whom were nonalcoholic, was studied. Distribution of ideal body weight and body mass index was below the median of controls, but very few patients were below the cut-off points for normalcy. Distribution of triceps skinfold and arm muscle circumference was also below the median and, in most patients, was also below the cut-off points. Serum visceral protein concentrations and anthropometric parameters each were reciprocally correlated with one another, but no correlation was observed between visceral proteins and anthropometric parameters. Serum visceral proteins appeared to correlate better with the degree of liver damage than with the degree of malnutrition. Therefore, anthropometric parameters seem preferable to serum visceral proteins for the assessment of nutritional status in patients with liver cirrhosis. (Journal of Parenteral and Enteral Nutrition11:130S-134S, 1987)

This paper reviews various parameters that are used to assess the nutritional and functional status of cancer patients. Available information shows that the nutritional status of cancer patients is correlated with their overall prognosis and outcome. However, little information exists concerning the use of nutritional indexes to evaluate the effectiveness of nutritional rehabilitation of cancer patients. It is emphasized that we should concentrate on developing nutritional parameters to assess the functional improvement of patients rather than their body structure and composition. (Journal of Parenteral and Enteral Nutrition11:13S-137S, 1987)