Showing papers on "Body water published in 1997"

Bioimpedance analysis: evaluation of leg-to-leg system based on pressure contact foot-pad electrodes

Abstract: Conventional single frequency bioimpedance analysis (BIA) systems require technician placement of arm and leg gel electrodes, a suitable location for recumbent measurements, and a separate measurement of body weight. The aim of this study was to evaluate a new single frequency 50 kHz leg-to-

Body composition of spinal cord injured adults.

Abstract: The prevalence of diseases associated with obesity, such as cardiovascular disease and diabetes mellitus, is higher in the spinal cord injury (SCI) population. Specifically, the mortality rate for cardiovascular disease is 228% higher in the SCI population. In addition, 100% of SCI individuals have osteoporosis in the paralysed extremities. These diseases are related to physical activity level, the level of the spinal cord lesion, and time post injury. Physically active SCI men and women have above-average fat mass (16 to 24% and 24 to 32%, respectively, compared with 15% for able-bodied men and 23% for able-bodied women), while sedentary SCI individuals have 'at-risk' levels of body fat (above 25% and 32%, respectively). The proportions and densities of the 3 main constituents comprising the fat-free body (mineral, protein and water) are altered following SCI. Bone mineral content decreases by 25 to 50%, and the magnitude of reduction is dependent on the level, completeness and duration of SCI. Because of denervation resulting in skeletal muscle atrophy, total body protein reduces by 30%, and total body water relative to bodyweight decreases by 15% following SCI. Indirect methods based on 2-component body composition models assume constant proportions and densities of mineral, protein, and water in the fat-free body. As a result, prediction equations based on 2-component models yield invalid estimates of fat and fat-free mass in the SCI population. Therefore, future research needs to directly quantify the proportions and densities of the constituents of the fat-free body in the SCI population relative to age, sex, physical activity level, level of the spinal cord lesion and time post injury, and to develop equations based on multicomponent body composition models.

Peak exercise response in relation to tissue depletion in patients with chronic obstructive pulmonary disease

Abstract: In several studies a correlation between body weight and peak exercise capacity has been found in patients with chronic obstructive pulmonary disease (COPD). In the present study a thorough analysis of the relationship between body composition and peak exercise performance was executed in 62 patients with clinically stable COPD. This was based on the hypothesis that particularly muscle mass, as the largest constituent of both fat-free mass (FFM) and body cell mass, is related to exercise capacity. Body composition was assessed using deuterium and bromide dilution techniques, to measure total body water (TBW) and extracellular water. From these measurements FFM:TBW/0.73, the ratio of ECW/intracellular water (ICW) and ICW-index (ICW/height2) were calculated. Peak exercise performance was measured using an incremental cycle ergometry test. The transfer factor of the lung for carbon monoxide (TL,CO) intrathoracic gas volume (ITGV), maximal expiratory and inspiratory mouth pressure, forced expiratory volume in one second (FEV1), FFM-index (FFM/height2), body mass index (weight/height2) and ICW-index correlated strongly (p<0.01) to peak oxygen consumption (V'O2). The ratio ECW/ICW correlated only weakly, but significantly, with peak V'O2 (r=-0.25, p<0.05). Stepwise regression analysis demonstrated that FFM-index and TL,CO explained 53% of the variation in peak V'O2. The results of this study furthermore indicate that severe FFM depletion is related to a blunted tidal volume response to peak exercise, a decreased peak oxygen pulse and an early anaerobic metabolism in patients with COPD. Depletion of muscle mass, measurable by assessment of fat-free mass, significantly effects peak oxygen consumption, ventilatory response, the oxygen pulse and anaerobic energy metabolism in patients with chronic obstructive pulmonary disease.

Body Weight Set-Points: Determination and Adjustment

Abstract: It is proposed that body weight, like body water and body temperature, is physiologically regulated. In the case of body weight, coordinated adjustments in both the intake and expenditure of energy serve to stabilize the weights of individuals at a specified level and to resist their displacement from this level. Obese individuals also display these behavioral and metabolic adjustments to weight perturbations and thus appear to actively resist efforts to reduce their weight from the elevated levels they ordinarily display. Experimental studies of genetically transmitted and diet-induced forms of obesity in animals similarly suggest a view of obesity as a condition of body energy regulation at an elevated set-point. An individual's set-point for regulated body weight is apparently adjustable, shifting over a lifespan in conjunction with naturally occurring but still unspecified physiologic changes. Experimentally, the set-point for body weight can be adjusted by manipulation of specific hypothalamic sites. Lesions of the lateral hypothalamus, for example, cause a chronic reduction in the level at which laboratory animals regulate body weight. It thus appears that hypothalamic mechanisms play a primary role in setting the level at which individuals regulate body weight, and it is likely that the genetic, dietary and other lifespan influences on body weight are expressed through these mechanisms.

The Relationship Between Dehydration and Parotid Salivary Gland Function in Young and Older Healthy Adults

Abstract: Background Saliva is essential for the maintenance of oral health. The primary constituent of saliva is water and, traditionally, decreased body water homeostasis has been linked with salivary dysfunction. This is consistent with the greater prevalence of dehydration and salivary gland dysfunction among the elderly. However, this association between dehydration and salivary dysfunction has never been tested using objective criteria. The purpose of this study was to determine the effect of body dehydration upon parotid salivary flow rates in young and older healthy adults. Methods Twelve young (20-40 years) and 12 older (60-80 years) healthy subjects abstained from food and beverage intake for 24 h (dehydration) and then underwent intravenous rehydration to replace all lost weight. Unstimulated and stimulated parotid salivary flow rates, weight, hematocrit, hemoglobin, serum sodium, plasma protein, creatinine, serum, and urine osmolality values were assessed at baseline, 24 h, and 1 h after the completion of rehydration. Results All subjects experienced a significant decrease in weight and increased levels of hematocrit, hemoglobin, plasma protein, and creatinine during dehydration with few age-related differences. Intravenous fluid replacement increased weight and decreased hematocrit, hemoglobin, plasma protein, and creatinine back to baseline values, demonstrating that subjects were metabolically rehydrated. Unstimulated (young and older, p = .0001) and stimulated (young, p > .05; older, p = .03) parotid flow rates decreased during the 24-h dehydration period, yet did not completely return (young and older unstimulated, p .05) to baseline values after rehydration. Conclusions These findings suggest that body dehydration is associated with decreased parotid salivary gland flow rates, and that these changes are generally age-independent in healthy adults. Furthermore, although subjects were metabolically rehydrated, unstimulated salivary flow rates remained significantly lower than baseline levels.

Low-dose recombinant human growth hormone increases body weight and lean body mass in patients with short bowel syndrome.

Abstract: OBJECTIVE: The authors investigate the effects of low dose recombinant human growth hormone (rhGH) on body composition and absorptive capacity in patients with short bowel syndrome from Crohn's disease. SUMMARY BACKGROUND DATA: Patients with short bowel syndrome usually are malnourished because of malabsorption. The anabolic effects of high doses of rhGH have been tested in different clinical catabolic conditions, recently including patients with short bowel syndrome. The authors have investigated the effects of low-dose rhGH in short bowel syndrome in a placebo-controlled crossover clinical trial. METHODS: Ten patients were treated with daily subcutaneous doses of rhGH/placebo (0.5 international units/kg-1 per week-1 = 0.024 mg/kg-1 per day-1) for 8 weeks in a randomized, double-blind, placebo-controlled crossover clinical trial with a minimum of 12 weeks wash-out. Absorptive capacity and biochemical parameters were investigated in a metabolic ward before treatment and during first and last week of treatment. Body composition was determined by DEXA-Scan (Lunar DPX, Scanexport Medical, Helsingborg, Sweden), impedance analysis, and whole body potassium counting. RESULTS: Low-dose rhGH doubled serum levels of insulin-like growth factor-1 (IGF-1) and increased body weight, lean body mass, and total body potassium by 5% (p < 0.05). Fat-free mass and total body water increased by 6% (p = 0.008). Increases in IGF-1 levels correlated with increases in fat-free mass (r = 0.77, p < 0.02). No significant changes in absorptive capacity of water, energy, or protein were detected. CONCLUSION: Eight weeks of low-dose rhGH treatment leads to increases in body weight, lean body mass, and fat-free mass in patients with short bowel syndrome, correlated to increases in IGF-1 levels.

Bioimpedance spectroscopy technique: intra-, extracellular, and total body water.

Abstract: The purpose of this study was to test the validity of a multiple frequency bioimpedance spectroscopy (BIS) technique that estimates extracellular fluid volume (ECV), intracellular fluid volume (ICV), and total body water (TBW). Thirteen healthy males (mean +/- SD: age, 23 +/- 3 yr; body mass, 80.6 +/- 14.7 kg) had their TBW and ECV measured by ingesting dilution tracers (7.27 g deuterium oxide, 1.70 g sodium bromide; blood samples at 0 and 4 h). ICV was calculated as TBW minus ECV. Impedance was measured (50-500 kHz) at rest, on a nonconducting surface, with a BIS analyzer. Electrode placement, posture, exercise, food/fluid intake, and ambient temperature were controlled. Dilution measures (TBW, 51.00 +/- 9.30; ECV, 19.88 +/- 3.14; ICV, 31.12 +/- 6.80 L) and BIS volumes (TBW, 50.03 +/- 7.67; ECV, 20.95 +/- 3.33; ICV, 29.04 +/- 4.51 L) were significantly different for ECV (P < 0.01) and ICV (P < 0.05); some individual differences were large. The correlation coefficients of dilution versus BIS volumes (r = 0.93 to 0.96) were significant at P < 0.0001; SEEs were: TBW, 2.23 L; ECV, 1.26 L; and ICV, 1.71 L. We concluded that BIS is valid for between-subject comparisons of body fluid compartments, is appropriate in clinical settings where change in ECV/ICV ratio is important, and should be used by comparing the required level of accuracy to the inherent technique error/variance.

Changes in Body Composition after Gastrectomy: Results of a Controlled, Prospective Clinical Trial

Abstract: To elucidate mechanisms involved in weight development after gastrectomy we have prospectively determined changes in body composition during the first year after similar operations. A total of 75 patients were enrolled who had a "curative operation" for gastric carcinoma; 42 were randomized to have a total gastrectomy, 23 total gastrectomy with a gastric substitute, and 10 subtotal gastrectomy. All reconstructions were done with a Roux-en-Y loop of the jejunum. Body composition was assessed preoperatively and at 6 and 12 months after gastrectomy by determining total body potassium and total body water. From these estimates, body cell mass, extracellular water, fat-free extracellular solids, and body fat were calculated with knowledge of the actual body weight and length. Triceps skinfold, arm muscle circumference, and grip strength were also measured. Weight loss (10% of preoperative weight) occurred early after the operations, after which body weight stabilized. Body cell mass remained essentially unchanged over the entire study period in contrast to body fat, which decreased by 40% during the first 6 months after gastrectomy. In accordance with the selective loss of body fat, we recorded a significant decrease in triceps skinfold figures and only a minor decrease of arm muscle circumference without obvious deterioration in hand grip strength. Weight loss after gastrectomy seems to be characterized by selective loss of body fat in contrast to other known clinical situations associated with impaired nutritional intake. Our observations form a basis for future clinical research aimed at preventing weight loss after these operations.

Reference Values for Body Proportions and Body Composition in Adult Women With Ullrich-Turner Syndrome

Abstract: This cross sectional study was undertaken to establish reference values for adult women with Ullrich-Turner syndrome (UTS) verified cytogenetically by blood karyotyping and not treated with growth hormone during childhood and adolescence, with respect to anthropometric and body composition measurements, for future evaluations of growth promoting therapy. All members of the Danish Turner Association were invited, and 79 women with UTS participated. Forty-two had the 45,X karyotype and the other 37 had different karyotypes. Outcome measures were height, sitting height, arm span, length of hand and foot, biacromial and biiliac diameter, and hip, waist, and head circumference. Bioelectrical impedance was performed, and total body water, lean body mass, and fat mass were calculated. Results give a very distinct anthropometric picture of adult women with the UTS, with a mean height of 146.8±6.7 cm (mean±SD), sitting height of 78.6±3.6 cm, arm span measurements of 147.9±7.1 cm, being between 3 and 4 standard deviation scores (SDS) below average; with a mean hand length of 17.0±1.1 cm and foot length of 22.4±1.2 cm, being around 1.5 SDS below average; a mean weight of 56.3±12.8 kg, head circumference of 55.3±2.0 cm and biacromial diameter of 36.5±2.0 cm, being around 0 SDS; and finally, biiliacal diameter of 29.5±2.2 cm, being 1.4 SDS above average. The average body mass index (BMI) in the study was 26.3±5.3 kg/m2. As a group, females with UTS are overweight when compared with a group of “normal” women, with a higher fat mass, a lower lean body mass, but with a comparable amount of total body water (in %). This study presents the first comprehensive reference data on body proportions in the adult UTS. It shows that adult women with the Ullrich-Turner syndrome has a characteristic anthropometric shape. The data should be of use for future evaluations of growth hormone treatment or other growth promoting therapy in the UTS on anthropometric and body composition variables. Am. J. Med. Genet. 72:403–408, 1997. © 1997 Wiley-Liss, Inc.

Coffee Consumption and Total Body Water Homeostasis as Measured by Fluid Balance and Bioelectrical Impedance Analysis

Abstract: To investigate the impact of coffee consumption on fluid balance, 12 healthy volunteers were supplied with a standardized diet for 2 days after having abstained from consumption of methylxanthines for 5 days. During the first day, fluid requirement was met by mineral water. On the following day the same amount of fluid was supplied and the mineral water was in part replaced by 6 cups of coffee containing 642 mg of caffeine. This led to an increase in 24-hour urine excretion of 753 +/- 532 ml (p < 0.001), a corresponding negative fluid balance and a concomitant decrease in body weight of 0.7 +/- 0.4 kg (p < 0.001). Total body water as measured with bioelectrical impedance analysis decreased by 1.1 +/- 1.2 kg or 2.7% (p < 0.01). Urinary excretion of sodium and potassium was elevated by 80 +/- 62 mmol or 66% (p < 0.01) and 14 +/- 12 mmol or 28% (p < 0.01), respectively.

Influence of Sodium Replacement on Fluid Ingestion Following Exercise-Induced Dehydration

Abstract: This study investigated the hypothesis that addition of Na+ to a rehydration beverage would stimulate drinking and augment restoration of body water in individuals dehydrated during 90 min of continuous treadmill exercise in the heat. Following a 3.0 +/- 0.2% decrease in body weight (BW), 6 subjects sat in a thermoneutral environment for 30 min to allow body fluid compartments to stabilize. Over the next 3 hr, subjects rehydrated ad libitum using either flavored/artificially sweetened water (H2O-R) or a flavored, 6% sucrose drink containing either 25 (LNa(+)-R) or 50 (HNa(+)-R) mmol/L NaCl. Results demonstrated that rapid removal of the osmotic stimulus, during H2O-R, and the volume-dependent dipsogenic stimuli, during HNa(+)-R, are important factors in limiting fluid intake during rehydration, compared to LNa(+)-R. It was also found that the pattern of fluid replacement and restoration of fluid balance following dehydration is influenced by the dehydration protocol used to induce the loss in total body water and the sodium content of the rehydration beverage.

Energy expenditure, substrate oxidation, and body composition in subjects with chronic alcoholism: new findings from metabolic assessment.

Abstract: There is some controversy as to the effect of ethanol on body weight and alcohol energy contribution to body mass. The aim of this study was to evaluate the effect of alcohol addiction on resting energy expenditure (REE) and body composition. Twelve patients with current alcoholism (A) without severe liver disease or lipid and carbohydrate malabsorption were compared with a group of healthy social drinkers (B) matched for sex, age, and height. Their caloric intake was computed on the basis of a food diary. REE was measured with indirect calorimetry, and body composition was assessed by both anthropometry and bioimpedance. A significant decrease in fat mass in A compared with B was found (14.8 +/- 5.39 vs. 19.0 +/- 3.50 kg; p < 0.05). No significant differences were observed in fat-free mass (FFM) or in total body water between the two groups. A showed higher REE values normalized by FFM than B (35.5 +/- 2.97 vs. 33.0 +/- 2.95 kcal/kgFFM; p < 0.05). The nonprotein respiratory quotient was significantly lower in A than in B (0.76 +/- 0.03 vs. 0.86 +/- 0.03; p < 0.001), and A showed significantly higher lipid oxidation and lower carbohydrate oxidation than B (p < 0.05). The daily caloric intake provided only by food ingestion was found to be significantly higher in controls, but because the percentage of alcohol calories of total energy intake was 46.3 +/- 6.80 in alcoholics and 13.6 +/- 3.59 in controls (p < 0.0001), the total caloric intake, computed as food intake plus alcohol intake, was higher in alcoholics than in control subjects. No statistical differences were found in urinary nitrogen excretion and fecal loss between groups. Patients with alcoholism showed an increased REE over predicted values and a preferential lipid oxidation with respect to controls; these findings could be related to induction of microsomal ethanol oxidizing system and to mitochondrial function adaptation secondary to chronic alcohol abuse. In either case, the effects of such changes in energy metabolism may contribute to alcohol associated hepatic injury.

Assessment of total body water using bioelectrical impedance analysis in neonates receiving intensive care

Abstract: AIMS To determine the most suitable anthropometric and impedance measures and current frequency for the application of bioelectrical impedance to neonates receiving intensive care; and to derive predictive models for the estimation of total body water. METHODS Twenty eight babies (median gestational age 30.5 weeks, range 24–38; median birthweight 1.388 kg, range 0.690–3.510) were each studied once during the first week after birth. Total body water was first measured by the method of dilution of isotopic water (H218O). Bioelectrical measurements were made using the tetrapolar surface electrode method from four main distal limb positions (right hand–right foot; right hand–left foot; left hand–left foot; left hand–right foot), the left upper arm–left thigh position and the left scapula–right buttock position, and using six frequencies ((500, 250, 100, 50, 10 and 5 kHz). Regression models, to predict total body water, which were both independent and dependent of body weight on the day of study, were derived. RESULTS Resistance readings at 50 kHz obtained from the distal limb positions performed best. There was no difference between the distal limb positions. There was no difference in the goodness of fit of the models when using each of three indices of conductor length, foot, spine and sternum. The model total body water (litres) (TBW) = 0.016 + 0.674 bodyweight(kg)−0.038 wt2 + 3.84 foot length (cm)2/resistance (50 kHz in OHMS) performed best, accounting for 99.5% of the variation in TBW, with a 95% prediction interval of 165 ml. The model TBW = 0.144 + 15.518 foot length (cm)2/resistance (50 kHz in ohms) accounted for 96.4% of the variation and had a 95% prediction interval of 420 ml. CONCLUSIONS Bioelectrical impedance analysis is a simple, non-invasive method of estimating total body water in neonates receiving intensive care. It can be applied to both the assessment of changes in body water and body composition.

Use of bioelectric impedance analysis and dual-energy X-ray absorptiometry for monitoring the nutritional status of dialysis patients

Abstract: Despite recent technological advances, inadequate nutrition has been clearly identified as a significant risk factor to survival of patients undergoing chronic maintenance dialysis therapy. Although body density by underwater weight and residual lung volume, total body water by isotope dilution, bone mineral content, and total body potassium measurements will provide a very accurate multicompartmental analysis of body composition, they are not applicable to routine clinical or field work. Because of availability and simplicity, in addition to anthropometry, bioelectrical impedance and dual energy X-ray absorptiometry have received the most attention from the renal community. Several studies have validated the use of total body water by BEI as a surrogate for isotope dilution methods in dialysis patients, whereas others have established an excellent correlation with the volume of distribution of urea as measured by urea kinetic volume. Bioimpedance analysis has been extensively validated in stable healthy populations for measurement of lean body mass. Results are similar to those obtained with hydrodensitometry and total body potassium. Several studies in dialysis patients have compared lean body mass measurements by BEI and DEXA. Although the number of patients studied is relatively small, there is a high degree of correlation and concordance between the two methods. Nevertheless, selective equations for specific patient populations may be required with both methodologies for individual clinical applications. Longitudinal follow-up of body composition using BEI and DEXA in dialysis patients is contingent on a stable hydration status and/or accurate estimation of extracellular volume status for appropriate corrections. Consistency of technique and standardization of BEI and DEXA equipment is essential for reproducibility of results. Equations used in calculations must be age, sex, race, body habitus, and population specific whenever possible. Multiple compartment models including BEI, DEXA and isotopic dilution provide the best current "gold standard" for body composition analysis. BEI methodology is a practical bedside tool for assessment of total body water, and provides more consistent and reproducible results than anthropometry.

Assessment of total body water and lean body mass from anthropometry, Watson formula, creatinine kinetics, and body electrical impedance compared with antipyrine kinetics in peritoneal dialysis patients.

Abstract: Background. Indirect methods such as anthropometry ( A), Watson formula ( W ), creatinine kinetics (CK ), and body electrical impedance (BEI ) are increasingly applied to determine total body water ( TBW ) and lean body mass (LBM ) in dialysis patients. These Introduction methods share the disadvantage that they have been validated for healthy men only. We studied which of In every nutritional survey of maintenance dialysis these four commonly applied methods can best be used patients, protein and energy malnutrition and wasting routinely in CAPD patients. are mentioned, affecting at least one-third of this Methods. TBW estimates obtained from A, W, CK, population [1 ]. A large proportion of patients on and BEI were compared with those obtained by a gold chronic ambulatory peritoneal dialysis (CAPD) show standard (antypirine distribution volume, ADV) in signs of malnutrition, possibly due to losses of protein eight CAPD patients. In addition, several BEI equa- and decreasing dietary intake of protein and energy: tions to derive lean body mass (LBM ) were compared for instance 41.6% of 224 CAPD patients from six with LBM estimated by ADV in order to determine centres in an international study on nutritional assesswhich equation is the most valuable for the assessment ment [2 ]. No significant differences between the nutriof LBM by BEI in CAPD patients. tional status of haemodialysis and CAPD patients have Results. TBW as ADV was 41.4±6.6 (mean±SD) L. been found [3 ]. TBW estimated by W, A and CK underestimated ADV Malnutrition is associated with an increased morbidby a mean±SD of 2.3±13, 5±8.4 and 12.3±10.9% ity [4]. The same holds true for Kt/V [5 ], a urea respectively. TBW as measured by BEI overestimated kinetic parameter of dialysis adequacy, which is a ADV by 2.5±8.8%. The correlation coefficients strong predictor of serum albumin concentration and between ADV‐TBW and TBW estimated by the indir- hence a powerful predictor of death in CAPD [6 ]. ect methods were r=0.88 ( A), r=0.87 (BEI ), r=0.82 Accurate determination of total body water in dialysis (CK ), and 0.68 ( W ). patients is important for assessment of fluid excess, for LBM estimated by ADV was 56.7±8.9 dialysis prescription by Kt/V, and for assessment of (mean±SD) kg; LBM by different BEI equations body composition or nutritional status. Calculation of ranged from 49.9±7 to 58.1±10.7 kg. total body water ( TBW ) or volume of distribution The correlation coefficient between LBM by ADV ( V ) as 0.6 times body weight is inaccurate, and deterand LBM according to the various BEI equations mination of these variables by a tracer dilution method ranged from 0.81 to 0.93. is laborious, invasive, and not well suited for routine Conclusion. A and BEI: can be used to estimate TBW, patient care. Therefore, non-invasive and indirect but the considerable SD (or inaccuracy) makes indi- methods such as anthropometry ( A), Watson formula vidual predictions hazardous. Considering the correla- ( W ), creatinine kinetics (CK), and bioelectrical impedtion coefficients and difference between LBM by ADV ance ( BEI) are increasingly applied for this purpose. and LBM according to different BEI equations, In order to study which of these methods can routinely Deurenberg’s formula can be advocated for use in the best be used for estimation of TBW and lean body estimation of LBM by BEI. mass in peritoneal dialysis patients, we compared estimations obtained by these methods with antipyrine distribution volume. The use of antipyrine in the

Validation of Multi‐Frequency Bioelectrical Impedance Analysis in Detecting Changes in Fluid Balance of Geriatric Patients

Abstract: OBJECTIVES: Multi-Frequency Bioelectrical Impedance Analysis (MFBIA) is a quick, simple, and inexpensive method to assess body fluid compartments. This study aimed at determining the validity of MFBIA in detecting clinically relevant changes of fluid balance in geriatric patients. DESIGN: A prospective, observational study. SETTING: The 22-bed Geriatric Department of the University Hospital Nijmegen. PARTICIPANTS: Hospitalized patients were eligible if they did not have a pacemaker, were not suffering from terminal illnesses, and did not have psychogeriatric diseases likely to interfere with capacity to consent or comply. During a 16-months period, 218 patients were admitted, of whom 78 patients were eligible and 53 consented to participate. MEASUREMENTS: Each subject's fluid balance was diagnosed twice a week as dehydrated, overhydrated, or euvolemic, based on standardized physical examination, laboratory tests, and weight evaluation. Changes in fluid balance were quantified by measuring total body water (TBW) and extracellular fluid (ECF) applying deuterium-and bromide-dilution techniques. Impedance at 1, 5, 50, and 100 kHz and body weight were measured daily. Sensitivity and Guyatt's responsiveness indexes of MFBIA in detecting dehydration and overhydration were determined. RESULTS: In total, 1071 MFBIA measurements were performed, during which 14 transitions from dehydration to euvolemia and 13 transitions from overhydration to euvolemia were monitored. Rehydration of dehydrated patients caused an increase in TBW and ECF of 3.4 ± 1.8 L and 1.9 ± 1.9 L, respectively, which resulted in significant decreases in impedance of 133 ± 67 Ω at 1 kHz and 93 ± 61 Ω at 100 kHz (P = .001). Treatment of overhydrated patients caused a TBW and ECF loss of 3.8 ± 4.2 L and 3.1 ± 3.8 L, respectively, which resulted in significant increases in impedance of 104 ± 72 Ω at 1 kHz and 81 ± 68 Ω at 100 kHz (P < .001). Sensitivity of a single MFBIA in diagnosing dehydration and overhydration was 14% and 17%, respectively. Responsiveness indexes of weighing and MFBIA for dehydration and overhydration were similar at all frequencies and greater than one. CONCLUSION: The sensitivity of a single impedance measurement in detecting dehydration and overhydration was low. However, responsiveness of serial measurements to intra-individual changes in fluid balance was good. Therefore, this noninvasive technique may be used in clinical practice to improve monitoring fluid balance in geriatric patients, especially when daily weighing is difficult. J Am Geriatr Soc 45:1345–1351, 1997.

Total body water and body composition in chronic peritoneal dialysis patients.

Abstract: In this investigation, total body water (TBW) in ten chronic peritoneal dialysis patients was studied by deuterium (TBW-2H), skinfold thickness (TBW-ST), Watson formula (TBW-WA), 58% of body weight (TBW-58%), and bioelectrical impedance (TBW-BIA), and these results were compared with the reference oxygen18 (TBW-18O) method. We also analyzed the fat-free mass (FFM) by skinfold thickness (FFM-ST), bioelectrical impedance (FFM-BIA), oxygen18 (FFM-18O), and creatinine kinetics method (FFM-CK). In addition, resting metabolic rate was measured by indirect calorimetry. Compared with TBW-18O, TBW-58% and TBW-BIA were significantly different (P

Regulation of body fluid volume and electrolyte concentrations in spaceflight

Abstract: Despite a number of difficulties in performing experiments during weightlessness, a great deal of information has been obtained concerning the effects of spaceflight on the regulation of body fluid and electrolytes. Many paradoxes and questions remain, however. Although body mass, extracellular fluid volume, and plasma volume are reduced during spaceflight and remain so at landing, the changes in total body water are comparatively small. Serum or plasma sodium and osmolality have generally been unchanged or reduced during the spaceflight, and fluid intake is substantially reduced, especially during the first of flight. The diuresis that was predicted to be caused by weightlessness, has only rarely been observed as an increased urine volume. What has been well established by now, is the occurrence of a relative diuresis, where fluid intake decreases more than urine volume does. Urinary excretion of electrolytes has been variable during spaceflight, but retention of fluid and electrolytes at landing has been consistently observed. The glomerular filtration rate was significantly elevated during the SLS missions, and water and electrolyte loading tests have indicated that renal function is altered during readaptation to Earth's gravity. Endocrine control of fluid volumes and electrolyte concentrations may be altered during weightlessness, but levels of hormones in body fluids do not conform to predictions based on early hypotheses. Antidiuretic hormone is not suppressed, though its level is highly variable and its secretion may be affected by space motion sickness and environmental factors. Plasma renin activity and aldosterone are generally elevated at landing, consistent with sodium retention, but inflight levels have been variable. Salt intake may be an important factor influencing the levels of these hormones. The circadian rhythm of cortisol has undoubtedly contributed to its variability, and little is known yet about the influence of spaceflight on circadian rhythms. Atrial natriuretic peptide does not seem to play an important role in the control of natriuresis during spaceflight. Inflight activity of the sympathetic nervous system, assessed by measuring catecholamines and their metabolites and precursors in body fluids, generally seems to be no greater than on Earth, but this system is usually activated at landing. Collaborative experiments on the Mir and the International Space Station should provide more of the data needed from long-term flights, and perhaps help to resolve some of the discrepancies between U.S. and Russian data. The use of alternative methods that are easier to execute during spaceflight, such as collection of saliva instead of blood and urine, should permit more thorough study of circadian rhythms and rapid hormone changes in weightlessness. More investigations of dietary intake of fluid and electrolytes must be performed to understand regulatory processes. Additional hormones that may participate in these processes, such as other natriuretic hormones, should be determined during and after spaceflight. Alterations in body fluid volume and blood electrolyte concentrations during spaceflight have important consequences for readaptation to the 1-G environment. The current assessment of fluid and electrolyte status during weightlessness and at landing and our still incomplete understanding of the processes of adaptation to weightlessness and readaptation to Earth's gravity have resulted in the development of countermeasures that are only partly successful in reducing the postflight orthostatic intolerance experienced by astronauts and cosmonauts. More complete knowledge of these processes can be expected to produce countermeasures that are even more successful, as well as expand our comprehension of the range of adaptability of human physiologic processes.

Assessment of Fat-Mass Loss During Weight Reduction in Obese Women

Abstract: Methods for assessing body fat mass (FM) loss were compared in 32 obese (body mass index [BMI], 29 to 41 kg/m2) premenopausal women before and after a weight loss of 13.0 +/- 3.4 kg (mean +/- SD). A four-component (4C) model was used as the criterion. The other methods were as follows: three-component models (body density with total body water [3W] or bone minerals [3M]), underwater weighing, dual-energy x-ray absorptiometry ([DXA] XR-26, software 2.5.2; Norland, Ft Atkinson, WI), bioelectric impedance analysis (BIA) with an obese-specific equation [Segal et al), skinfolds (Durnin and Womersley), and an equation with BMI (Deurenberg et al). The 3W model (bias +/- SD, 0.5 +/- 0.4 kg), XR-26 (0.6 +/- 2.1 kg), and BMI equation (-0.3 +/- 2.1 kg) gave practically unbiased mean estimations of fat loss. All other methods underestimated fat loss by at least 1.6 kg (range of bias, -2.7 to -1.6 kg). The small bias (0.7 +/- 1.0 kg) between underwater weighing and model 4C before weight reduction indicates that the two-component assumptions were valid in premenopausal, weight-stable obese women. However, particularly the water fraction of the fat-free body component (4C model) was increased after weight reduction (before, 72.9% +/- 1.4%; after, 75.7% +/- 2.2%), making both underwater weighing and the 3M model uncertain for assessment of body composition changes. A general tendency for overestimating FM was seen before and more clearly after weight reduction. However, most methods underestimated fat loss, apparently because of unexpected changes in hydration of the fat-free body component.

Energy expenditure using isotope-labelled water (2H218O), exercise performance, skeletal muscle enzyme activities and plasma biochemical parameters in humans during 95 days of endurance exercise with inadequate energy intake.

Abstract: Two men, R.F. and M.S., pulled sledges each with starting masses of 222 kg, 2300 km across Antarctica. Exercise was performed for approximately 10 h each day for 95 days. Despite an average energy intake of 21.3 MJ · day−1 both subjects lost more than 25% of body weight. Energy expenditure was measured using energy balance data (EB) and isotope-labelled water (2H2 18O). Isotope doses were taken on day 0 and day 50 of the expedition. During the first 50 days both methods gave reasonable agreement, giving energy expenditures of 38.3 (EB) and 35.5 (2H2 18O) MJ · day−1 in R.F. and 28.6 (EB) and 29.1 (2H2 18O) MJ · day−1 in M.S. The isotope data for days 20–30 yielded exceptional values of 44.6 MJ · day−1 in R.F. and 48.7 MJ · day−1 in M.S. Estimates of energy expenditure between day 51 and day 96 were much lower and although the methods were in agreement for R.F. – 24.1 (EB) and 23.1 (2H2 18O) MJ · day−1, there was poor agreement for MS – 26.8 (EB) and 18.8 (2H2 18O) MJ · day−1. However, some practical difficulties occurred during this second period and there were also problems arising from marked increases in body water that made estimates of body mass and composition change difficult to interpret. The latter problems were probably due to malnutrition, which may have also been responsible for surprising increases in urinary excretion of 2H and 18O observed in both men at around day 81. These increases may reflect the release of label incorporated into molecules other than water which do not normally freely exchange with the body water pool under the circumstances of marked malnourishment. Following the expedition, both men showed declines in maximal O2 consumption (V˙O2 max , 53.6 to 41.2 ml O2 kg−1 · min−1 in R.F., 58.1–46.0 ml O2 kg−1 · min−1 in M.S.); maximal voluntary isometric force production in different muscle groups (up to 19.9% in R.F. and 55.8% in M.S.) and both cytoplasmic and mitochondrial skeletal muscle enzyme activities (up to 56% in R.F. and 63% in M.S.). Plasma samples taken during the expedition showed low glucose levels, inappropriately high insulin levels, and declines in testosterone and luteinizing hormone. Thyroxine, cholesterol, albumin and triglyceride levels remained normal.

The effects of high altitude trekking on body composition and resting metabolic rate.

Abstract: Resting metabolic rate (RMR) and body composition were evaluated in 12 healthy volunteers before and after 16 days of high altitude trekking and climbing. RMR was measured by indirect calorimetry and body composition by electrical impedance. A 29% reduction in energy intake during high altitude exposure was observed. Fat mass loss averaged about 2.2 kg (p < 0.05) and lean body mass about 1.1 kg, which was almost significant (p = 0.07). As expected, estimated RMR at the end of the expedition--calculated by predictive formulae including body fat and lean body mass as covariates--was significantly reduced by 119 kcal/day as a consequence of the reduction in body weight. Measured RMR values, on the contrary, did not show any significant decline. In conclusion our study showed that high altitude trekking induced a weight loss due approximately 2/3rds to fat mass and 1/3rd to lean body mass. Decreased energy efficiency, which was still present several days after returning to sea level, may have helped contribute to weight loss due to reduced energy intake.

Deuterium and bromide dilution, and bioimpedance spectrometry independently show that growth hormone-deficient adults have an enlarged extracellular water compartment related to intracellular water.

Abstract: GH has a strong influence on body composition. However, the effects of GH deficiency in adults on water compartments are not well understood. Therefore, extracellular water (ECW) and total body water were independently determined by deuterium and bromide dilution and by bioimpedance spectrometry in GH-deficient (GHD) adults and compared to those in controls, matched for age, sex, body weight, and height. The results show that the percent body fat was significantly (P < 0.05) higher, and total body water and intracellular water (ICW) were significantly lower in GHD adults for males, females, and both sexes combined. ECW was not significantly different between the two groups. ECW/ICW in GHD adults (0.42 ± 0.03) was significantly (P < 0.01) higher than that in controls (0.39 ± 0.02). There was a significant positive relation between the ECW/ICW ratio and the percent body fat. These results were confirmed by the bioimpedance spectrometry measurements.

Serum leptin levels during recombinant human GH therapy in adults with GH deficiency.

Abstract: Objective: Recent studies suggest an involvement of the obese (ob) gene and its product leptin in the regulation of body fat. Since adults with growth hormone deficiency (GHD) have a high body fat mass which can be normalized with recombinant human (rh) GH therapy, we investigated whether GH influences serum leptin directly or indirectly via its lipolytic effect. Design: Fourteen adults with GHD were treated with subcutaneous injections of rhGH given every evening for 52 weeks. Serum leptin, fat mass and body fat percentage were measured at baseline and after 4 and 52 weeks of treatment. Methods: Serum leptin was measured with a commercially available RIA. Total body water was determined by dilution of deuterium. Fat free mass was estimated by assuming a hydration of 73%. Fat mass was estimated by subtracting fat free mass from weight. Results: At baseline, serum leptin levels were exponentially related to body fat percentage (r=0.88; P<0.0005). rhGH treatment for 4 weeks did not significantly influence serum leptin levels, whereas treatment for 52 weeks significantly decreased serum leptin levels (15.6 6 2.9 to 10.8 6 2.1 mg/l; P o 0:020). Fat percentage was significantly decreased after 52 weeks of treatment (37.6 6 2.1 to 33.8 6 2.5%; P < 0:0005). The decrease in serum leptin could largely be explained by the decrease in body fat percentage, whereas the relation between leptin and body fat percentage did not change. Conclusions: The influence of GH on serum leptin is indirect, via its effect on body fat percentage.