Showing papers on "Body water published in 2003"

Fluid balance and endurance exercise performance

Abstract: Dehydration alters cardiovascular, thermoregulatory, central nervous system, and metabolic functions. One or more of these alterations will degrade endurance exercise performance when dehydration exceeds 2% of body weight. These performance decrements are accentuated by heat stress. To minimize the adverse consequences of body water deficits on endurance exercise performance, it is recommended that fluid intake be sufficient to minimize dehydration to less than 2% of body weight loss. This can usually be achieved with fluid intakes of under 1 L x h(-1).

Icodextrin Improves the Fluid Status of Peritoneal Dialysis Patients: Results of a Double-Blind Randomized Controlled Trial

Abstract: Worsening fluid balance results in reduced technique and patient survival in peritoneal dialysis. Under these condi- tions, the glucose polymer icodextrin is known to enhance ultrafiltration in the long dwell. A multicenter, randomized, double-blind, controlled trial was undertaken to compare ico- dextrin versus 2.27% glucose to establish whether icodextrin improves fluid status. Fifty patients with urine output 750 ml/d, high solute transport, and either treated hypertension or untreated BP 140/90 mmHg, or a requirement for the equiv- alent of all 2.27% glucose exchanges, were randomized 1:1 and evaluated at 1, 3, and 6 mo. Members of the icodextrin group lost weight, whereas the control group gained weight. Similar differences in total body water were observed, largely ex- plained by reduced extracellular fluid volume in those receiv- ing icodextrin, who also achieved better ultrafiltration and total sodium losses at 3 mo (P 0.05) and had better maintenance of urine volume at 6 mo (P 0.039). In patients fulfilling the study's inclusion criteria, the use of icodextrin, when compared with 2.27% glucose, in the long exchange improves fluid removal and status in peritoneal dialysis. This effect is appar- ent within 1 mo of commencement and was sustained for 6 mo without harmful effects on residual renal function.

Fluid status in CAPD patients is related to peritoneal transport and residual renal function: evidence from a longitudinal study

Abstract: Background. Both peritoneal transport characteristics as well as residual renal function are related to outcome in patients treated with continuous ambulatory peritoneal dialysis (CAPD). It has been suggested that part of this relationship might be explained by an effect of both parameters on the fluid state in CAPD patients or by the relationship between inflammation and peritoneal transport. Methods. In the present study, the relationship between fluid state [extracellular water (ECW) (sodium bromide); total body water (TBW) (deuterium oxide)] with peritoneal transport characteristics (2.27% glucose dialysateuplasma creatinine [DuP (creat)] ratio), residual renal function (residual glomerular filtration rate [rGFR] by urine collection) and C-reactive protein (CRP) was assessed in 37 CAPD patients in a crosssectional and longitudinal design, with 25 patients completing the study. Results. In the cross-sectional part ECW, corrected for height (ECW:height), was inversely related to rGFR (rs0.40, Ps0.016), whereas during the longitudinal part, DuP[creat] was related to the change in ECW (rs0.40, Ps0.05). Neither DuP[creat] nor rGFR were related to CRP, whereas a significant relationship was observed between ECW:height and CRP (rs0.58, Ps0.0001). Patients were dichotomized according to rGFR (- 2o r) 2m lumin). Despite a higher daily peritoneal glucose prescription (216.3"60.0 vs 156.5"53.0 gu24 h; Ps0.004) and peritoneal ultrafiltration volume (1856"644 vs 658"781 mlu24 h, respectively; Ps0.0001), the patients with a rGFR - 2m lumin showed a higher ECW:height compared with the group with rGFR ) 2m lumin (12.5"3.8 vs 9.2"2.2 lum, respectively; Ps0.003). Results for TBW were comparable. Conclusion. Fluid state was significantly related to peritoneal transport characteristics and rGFR. The larger ECW:height in CAPD patients with a negligible rGFR existed despite a higher peritoneal ultrafiltration volume and higher peritoneal glucose prescription. These findings raise doubts as to whether fluid state in CAPD patients with a diminished rGFR can be adequately controlled on standard glucose solutions without an additional sodium and fluid restriction. The preliminary finding of a relationship between CRP and fluid state might suggest a relationship between overhydration and inflammation.

Validity of six field and laboratory methods for measurement of body composition in boys.

Abstract: Objective: To determine the validity of the following six body composition methods against a reference method (three-component model): air displacement plethysmography (BODPOD); estimation from body density using BODPOD; skinfold thickness using the Slaughter equations; bioelectrical impedance, both leg-leg (TANITA) and hand—foot (Bodystat) approaches; and total body water. Research Methods and Procedures: Forty-two healthy white 10- to 14-year-old boys (mean age, 12.9 ± 1.0 years) were enrolled in this study. Measures of body fat percentage and body fat mass derived from the three-component model were used as the reference method. Validity of all of the other methods was assessed by comparison against the reference by calculation of biases and limits of agreement. Results: Mean body fatness measured using the reference method was 16.4 ± 11.6% and 8.7 ± 7.0 kg. Estimates of fatness from total body water had the narrowest limits of agreement relative to the reference (+0.9 ± 5.0% body fat; +0.5 ± 2.9 kg fat mass). For all other methods tested, we observed large biases and very wide limits of agreement. Discussion: This study suggests that the validity of newer field and laboratory methods for estimation of body composition is poor in adolescent boys. For applications where high accuracy of estimation at the individual level is essential, only reference methods would be acceptable.

Creatine Supplementation Increases Total Body Water Without Altering Fluid Distribution.

Abstract: OBJECTIVE: To examine the effects of oral creatine (Cr) monohydrate supplementation on muscle Cr concentration, body mass, and total body water (TBW), extracellular water (ECW), and intracellular water (ICW) volumes. DESIGN AND SETTING: After an overnight fast, urinary Cr and creatinine concentrations, muscle Cr concentration, body mass, TBW, ECW, and ICW were measured, and subjects were randomly assigned to either a Cr or a placebo (P) group. The Cr group ingested 25 g/d of Cr for 7 days (loading phase) and 5 g/d for the remaining 21 days (maintenance phase), whereas the P group ingested a sucrose P using the same protocol. All the measures were reassessed immediately after the loading and maintenance phases. SUBJECTS: Sixteen men (age = 22.8 +/- 3.01 years, height = 179.8 +/- 7.1 cm, body mass = 84.8 +/- 11.2 kg) and 16 women (age = 21.8 +/- 2.51 years, height = 163.4 +/- 5.9 cm, body mass = 63.6 +/- 14.0 kg) involved in resistance training volunteered to participate in this study. MEASUREMENTS: Muscle Cr concentration was determined from the vastus lateralis muscle using a percutaneous needle-biopsy technique. Total body water, ECW, and ICW volumes were assessed using deuterium oxide and sodium bromide dilution analyses. RESULTS: The Cr group experienced a significant increase in muscle Cr concentration, body mass, and TBW. The P group experienced a small but significant increase in TBW only. CONCLUSIONS: The Cr supplementation protocol was effective for increasing muscle Cr concentrations, body mass, and TBW; however, fluid distribution was not changed.

Interactions between serum leptin, the insulin-like growth factor-I system, and sex, age, anthropometric and body composition variables in a healthy population randomly selected.

Abstract: Summary objective Leptin secretion is influenced by many factors and the GH/IGF axis plays an important role in the regulation of body composition, but the physiological interactions between leptin and the IGF-I system remain unknown In this study we investigated the relationship between leptin, the IGF-I system, and sex, age, anthropometric and body composition variables in a group of healthy adults randomly selected design A cross-sectional study patients The study included 268 subjects, representative of the whole population of the city of L’Hospitalet de Llobregat in sex and age distribution: 134 men aged 41·4 years, range 15–70 years; and 134 women, aged 40·7 years, range 15–70 years measurements Body mass index (BMI) was calculated, and body composition was determined by using a bioelectrical impedance analyser Serum leptin concentrations were determined by using a radioimmunoassay (RIA) Serum total IGF-I concentrations, after acid–ethanol extraction, were also measured by RIA Serum free IGF-I concentrations were determined by an enzymoimmunometric assay Serum IGFBP3 concentrations were determined by RIA Plasma basal TSH concentrations were determined by a specific electrochemiluminescence assay results In men the BMI was similar in all decades and waist/hip ratio increased in the last three decades Fat-free mass decreased by decade We observed an increase in leptin in the fourth decade with a decrease in IGF-I, free IGF-I and IGFBP3 throughout the decades Basal TSH showed an increase in the last two decades In women, BMI, waist/hip ratio and fat mass increased significantly in the last decades Leptin concentrations increased in the last decades and total IGF-I, free IGF-I and IGFBP3 decreased by decade without changes in basal TSH concentration In men, there was a positive correlation between leptin and BMI, waist/hip ratio, total body water, fat-free mass and fat mass, and these anthropometric and body composition variables showed a negative correlation with free IGF-I and IGFBP3, without any correlation with total IGF-I In women, there was a positive correlation between leptin and BMI, waist/hip ratio, total body water, fat-free mass, and fat mass, which showed a negative correlation with total IGF-I and IGFBP3, without any correlation with free IGF-I In men, total IGF-I was negatively correlated with waist/hip ratio without any correlation with the other variables and free IGF-I was negatively correlated with BMI and waist/hip ratio, and IGFBP3 did not show any correlation In women, total IGF-I, free IGF-I and IGFBP3 were negatively correlated with BMI, waist/hip ratio and fat mass The multiple linear regression analysis produced a model that explained 60·5% of leptin variability in men and 40% in women Notably, only age, BMI, fat mass and waist/hip ratio brought an independent significant contribution to leptin variability The final model also explained 28·2% and 60·4% of total IGF-I variability and 17·2% and 27·4% of free IGF-I variability in men and women, respectively Age and leptin contributed to free IGF-I variability in men, and age and fat mass were significantly and independently associated with total IGF-I in women conclusions In this well-characterized population of controls randomly selected without chronic disease or drug administration and with biochemically confirmed euthyroidism, we found that both men and women had a significant correlation between leptin levels and the IGF-I system, and anthropometric and body composition variables, but that leptin did not regulate the IGF-I system, and that the IGF-I system did not regulate leptin synthesis and secretion

Comparison of body composition methods in overweight and obese children.

Abstract: The objective of the present study was to investigate the accuracy of percent body fat (%fat) estimates from dual-energy X-ray absorptiometry, air-displacement plethysmography (ADP), and total body...

Body composition during normal pregnancy: reference ranges

Abstract: Maternal body composition undergoes a deep adaptative change during the course of pregnancy. Fat mass, fat-free mass, and total body water (TBW) increase in different ways and their effects on pregnancy outcome represent a field of major interest in perinatal medicine. The aim of this study was to evaluate the changes in maternal body composition [maternal weight, TBW, intracellular water (ICW) and extracellular water (ECW)] during healthy pregnancy by using bioimpedance analysis (BIA). A total of 170 healthy pregnant women, aged 22-44 years, volunteered to participate in our study. The BIA measurements were carried out with a Tefal BIA scale determining resistance and reactance. Lukaski's multiple-regression equation was used to estimate TBW and ICW and ECW were computed using the prediction formula of Segal. The evaluations were performed at 10-38 weeks' gestation, every 3-4 weeks, and hematocrit was determined at every time interval. Analysis of variance and multiple comparisons of Bonferroni were performed to compare variables among the different study intervals. Second-order polynomial interpolation was used to obtain percentile values for each bioimpedance parameter. Percentile bioimpedance values of the healthy population are provided at each study time, by showing the mean value and the 5th, 25th, 75th, 95th percentiles. Moreover, normal reference ranges for TBW are provided for each gestational age, in relation to maternal weight gain. Reactance, TBW, and ICW enhance slightly during the course of gestation. Tetrapolar BIA could be an easy and practical tool for evaluating changes of maternal body components during pregnancy. It could also provide indirect proof of the normal hemodilution occurring in normal pregnancies. Moreover, fat mass deposition, and not only fluid retention, seems to be responsible for the mother's gestational weight gain, since reactance is an indirect parameter in estimating fat mass amount.

Total body water estimation using bioelectrical impedance: a meta-analysis of the data available in the literature

Abstract: Bioelectric impedance analysis (BIA) is commonly used in clinical settings and field studies for estimating total, extracellular, and intracellular water compartments. The objective of the present study was to carry out a meta-analysis of published reports in which total body water (TBW) was estimated using BIA techniques and comparisons were made with reference values. We identified 16 reports conducted among healthy and obese adults and individuals with chronic renal failure. Based on the weighted mean difference, we found that those studies using only multi-frequency BIA did not significantly overestimate the TBW compared with the reference values. Thus, among BIA techniques, multi-frequency BIA seems to be a more accurate method for estimating the TBW compartment for healthy and obese adults and for those with chronic renal failure.

Total energy expenditure and body composition changes following peripheral blood stem cell transplantation and participation in an exercise programme.

Abstract: The purpose of this investigation was to assess changes in total energy expenditure (TEE), body weight (BW) and body composition following a peripheral blood stem cell transplant and following participation in a 3-month duration, moderate-intensity, mixed-type exercise programme. The doubly labelled and singly labelled water methods were used to measure TEE and total body water (TBW). Body weight and TBW were then used to calculate percentage body fat (%BF), and fat and fat-free mass (FFM). TEE and body composition measures were assessed pretransplant (PI), immediately post-transplant (PII) and 3 months post-PII (PIII). Following PII, 12 patients were divided equally into a control group (CG) or exercise intervention group (EG). While there was no change in TEE between pre- and post-transplant, BW (P<0.01) and FFM (P<0.05) significantly decreased during the same period. Participation in the exercise programme led to increases in TEE to levels that were both higher than pre- and post-transplant measures (P<0.01). By PIII, the exercising patients also showed gains in FFM (P<0.01) in association with a reduction in %BF (P<0.05). Exercise has a functionally important role in preserving and increasing skeletal mass in the rehabilitation phase of cancer patients.

Body composition and components of energy expenditure in children with end-stage liver disease.

Abstract: Background: Better understanding of body composition and energy metabolism in pediatric liver disease may provide a scientific basis for improved medical therapy aimed at achieving optimal nutrition, slowing progression to end-stage liver disease (ESLD), and improving the outcome of liver transplantation. Methods: Twenty-one children less than 2 years of age with ESLD awaiting liver transplantation and 15 healthy, aged-matched controls had body compartment analysis using a four compartment model (body cell mass, fat mass, extracellular water, and extracellular solids). Subjects also had measurements of resting energy expenditure (REE) and respiratory quotient (RQ) by indirect calorimetry. Nine patients and 15 control subjects also had measurements of total energy expenditure (TEE) using doubly labelled water. Results: Mean weights and heights were similar in the two groups. Compared with control subjects, children with ESLD had higher relative mean body cell mass (33 ± 2% vs 29 ± 1% of body weight, P < 0.05), but had similar fat mass, extracellular water, and extracellular solid compartments (18% vs 20%, 41% vs 38%, and 7% vs 13% of body weight respectively). Compared with control subjects, children with ESLD had 27% higher mean REE/body weight (0.285 ± 0.013 vs 0.218. ± 0.013 mJ/kg/24h, P < 0.001), 16% higher REE/unit cell mass (P < 0.05); and lower mean RQ (P < 0.05). Mean TEE of patients was 4.70 ± 0.49 mJ/24h vs 3.19 ± 0.76 in controls, (P < 0.01). Conclusions: In children, ESLD is a hypermetabolic state adversely affecting the relationship between metabolic and non-metabolic body compartments. There is increased metabolic activity within the body cell mass with excess lipid oxidation during fasting and at rest. These findings have implications for the design of appropriate nutritional therapy.

Dehydration in stressed ruminants may be the result of a cortisol-induced diuresis.

Abstract: The effect on water and electrolyte balance of stress, simulated by intravenous infusion of cortisol, was studied using 24 18-mo-old Merino wethers (37.0 +/- 0.94 kg mean body weight [BW]) over 72 h. The sheep were allocated to one of four groups: 1) no water/no cortisol (n = 6); 2) water/no cortisol (n = 4); 3) no water/cortisol (n = 6); and 4) water/cortisol (n = 4). Animals allocated to the two cortisol groups were given 0.1 mg x kg BW(-1) x h(-1) of hydrocortisone suspended in isotonic saline to simulate stress for the duration of the experiment. Total body water, plasma cortisol, osmolality and electrolytes, and urine electrolytes were determined at 24-h intervals for 72 h. In the presence of cortisol, total body water was maintained in the face of a water deprivation insult for 72 h. Water deprivation alone did not induce elevated plasma concentrations of cortisol, in spite of a 13% loss of total body water between 48 and 72 h. Infusion of cortisol was found to increase urine output (P = 0.003) and decrease total urinary sodium output (P = 0.032), but had no effect on plasma electrolyte levels or water intake. Water deprivation was found to increase plasma sodium concentrations (P = 0.037). These results indicate that sheep given cortisol to simulate stress suffer from a loss of body water in excess of that associated with a loss of electrolytes, and support the hypothesis that elevated physiological concentrations of cortisol induce a diuresis in ruminants that contributes to dehydration.

Body composition estimated by bioelectrical impedance in the Swedish elderly. Development of population-based prediction equation and reference values of fat-free mass and body fat for 70- and 75-y olds.

Abstract: Objective: To develop a bioelectrical impedance (BIA) prediction equation for fat-free mass (FFMBIA) and present reference values of FFM and body fat (BF) for healthy Swedish elderly from population-based representative samples. Subjects: This study is based on 823 (344 males, 479 females) participants from two systematic samples of birth cohorts in Goteborg aged 70 (cohort H70V, 201 males and 299 females) and 75 (cohort NORA75, 143 males and 180 females). Methods: Body composition was measured with BIA (BIA-101, RJL system, Detroit) in both cohorts and was estimated by a four-compartment (4C) model from total body water (TBW) and total body potassium (TBK) in a sub-sample of the NORA75 cohort. The FFMBIA was validated against the FFM from the 4C model (FFM4C). Results: The FFMBIA correlated well with FFM4C (r=0.95, SEE=2.64 kg). The FFMBIA (kg) in 70-y-old males and females were 58.5±5.4 and 43.4±4.4, and for 75-y-old males and females were 56.1±4.7 and 42.5±4, respectively. The body fat in kg (FM) among 70-y-old males and females were 25.2±8.1 and 25.7±8.4, and for 75-y-old males and females were 21.7±7.1 and 22.8+7.2, respectively. The percent body fat (BF%) among 70-y-old males and females were 29.5±5.8 and 36.3±6.4, and for 75-y-old males and females were 27.3±6 and 34.1±6.1, respectively. Conclusion: The FFM, FM and BF% from this study might be used as reference values for Swedish elderly aged 70 and 75 y. Sponsorship: See acknowledgement.

Effect of licorice on the reduction of body fat mass in healthy subjects.

Abstract: The history of licorice, as a medicinal plant, is very old and has been used in many societies throughout the millennia. The active principle, glycyrrhetinic acid, is responsible for sodium retention and hypertension, which is the most common side-effect. We show an effect of licorice in reducing body fat mass. We studied 15 normalweight subjects (7 males, age 22–26 yr, and 8 females, age 21–26 yr), who consumed for 2 months 3.5 g a day of a commercial preparation of licorice. Body fat mass (BFM, expressed as percentage of total body weight, by skinfold thickness and by bioelectrical impedance analysis, BIA) and extracellular water (ECW, percentage of total body water, by BIA) were measured. Body mass index (BMI) did not change. ECW increased (males: 41.8±2.0 before vs 47.0±2.3 after, p<0.001; females: 48.2±1.4 before vs 49.4±2.1 after, p<0.05). BFM was reduced by licorice: (male: before 12.0±2.1 vs after 10.8±2.9%, p<0.02; female: before 24.9±5.1 vs after 22.1±5.4, p<0.02); plasma renin activity (PRA) and aldosterone were suppressed. Licorice was able to reduce body fat mass and to suppress aldosterone, without any change in BMI. Since the subjects were consuming the same amount of calories during the study, we suggest that licorice can reduce fat by inhibiting 11β-hydroxysteroid dehydrogenase Type 1 at the level of fat cells.

Weaning Mass Affects Changes in Body Composition and Food Intake in Harbour Seal Pups during the First Month of Independence

Abstract: In phocid seals, the transition to nutritional independence is abrupt, with females abandoning their offspring after weaning and returning to sea. We hypothesized that body size at weaning may play an important role in the nature of this transition. We studied the changes in body composition and water flux of newly weaning harbour seals over the first 4–6 wk postweaning. Thirty‐three pups were dosed with deuterium oxide to estimate total body water (TBW) and a subset of 24 was dosed twice to estimate changes in body composition and water flux. All pups lost body mass over the study period, but TBW increased during the period of mass loss, indicating continued lean tissue growth. Combined data from this and our early study indicated that heavy (>median mass) pups were relatively fatter (41.0% vs. 37.1%) and had significantly greater total body energy at weaning than did light (≤ median mass) pups. Percentage TBW declined linearly over time in light pups but was constant in heavy pups for the first...

Studies on human body composition during the first 4 months of life using magnetic resonance imaging and isotope dilution.

Abstract: Assessing body composition during infancy requires data for the so-called reference infant. Currently available data for this purpose need to be updated and extended using methods based on principles different from those used previously to define the reference infant. Thus, magnetic resonance imaging was applied to full-term healthy boys (n = 25) and girls (n = 21), 4-131 d old, to estimate adipose tissue volume (ATV) and the amounts of s.c. and non-s.c. adipose tissue (AT). Total body water was estimated using isotope dilution. Total body fat (TBF), fat free weight (FFW) and the degree of hydration in FFW were calculated. Increases in weight, TBF, and FFW with age agreed with current reference data, although when compared with the reference, a slightly more rapid increase in % TBF was observed for boys. The degree of hydration in FFW was 78.9 +/- 4.5% (n = 45). Both sexes showed significant increases with age in s.c. ATV (14.7 and 13.0 mL/d for boys and girls, respectively) and in non-s.c. ATV (1.58 and 1.26 mL/d, respectively). Subcutaneous ATV was 90.5 +/- 1.8% (boys) and 91.1 +/- 1.9% (girls) of total ATV. In conclusion, a pronounced increase with age in the amount of AT was demonstrated involving a considerable gain in s.c. fat during early life. Except for % TBF in boys, changes in body composition with age agreed with current reference data.

A longitudinal comparison of body composition by total body water and bioelectrical impedance in adolescent girls.

Abstract: Previous studies have assessed the ability of bioelectrical impedance analysis (BIA) to estimate body composition cross-sectionally, but less is known about the ability of BIA to detect changes in body composition longitudinally over the adolescent growth period. Body composition was assessed by isotopic dilution of H(2)(18)O and BIA in 196 initially nonobese girls enrolled in a longitudinal study. Two prediction equations for use in our population of girls were developed, one for use premenarcheally and one for use postmenarcheally. We compared estimates from our equation with those derived from several published equations. Using longitudinal data analysis techniques, we estimated changes in fat-free mass (FFM) and percentage body fat (%BF) over time from BIA, compared with changes in FFM and % BF estimated by H(2)(18)O. A total of 422 measurements from 196 girls were available for analysis. Of the participants, 26% had one measurement of body composition, 43% had two measurements of body composition and 31% had three or more measurements of body composition. By either H(2)(18)O or BIA, the mean %BF at study entry was 23% (n = 196) and the mean %BF at 4 y postmenarche was 27% (n = 133). In our cohort, the best predictive equations to estimate FFM by BIA were: PREMENARCHE: FFM = -5.508 + (0.420 x height(2)/resistance) + (0.209 x weight) + (0.08593 x height) + (0.515 x black race) - (0.02273 x other race). POSTMENARCHE: FFM = -11.937 + (0.389 x height(2)/resistance) + (0.285 x weight) + (0.124 x height) + (0.543 x black race) + (0.393 x other race). Overall, we found that BIA provided accurate estimates of the change in both FFM and %BF over time.

Regulation of body composition by androgens.

Abstract: Human body can be viewed simplistically as being composed of fat-free and fat mass. With more sophisticated techniques, body composition can be broken down into fat mass, skeletal muscle mass, nonmuscle lean mass, visceral mass and bone mineral content. Similarly, it is possible to obtain estimates of total body water and intracellular and extracellular water contents. Regardless of the model of body composition assessment, it is evident that androgens are important determinants of body composition; there is no body compartment that is not directly or indirectly affected by androgens. The effects of androgens on skeletal muscle mass have received the greatest attention in recent literature; however, growing body of evidence suggests that androgens also regulate fat mass, bone mineral content, nonmuscle soft tissues and body water.

Dehydration of football referees during a match

Abstract: Objectives: To study hydration status in referees (main) and assistant referees (linesmen) during official football matches. Methods: Twelve male football referees were evaluated; all were volunteers. Before and after each match, the referee and one of the assistants were weighed without clothes and a blood sample was taken. Total water loss was determined for each subject from the change in body weight. The main haematological variables were analysed in the blood samples. Total plasma protein concentration and osmolarity were also determined. Variation in plasma volume was determined from changes in packed cell volume and a combination of changes in packed cell volume and haemoglobin concentrations. Results: During a match, total body water loss was 1.60 (0.13) litres, equivalent to 2.05 (0.18)% of body weight. Body weight was reduced by 1.55 (0.12)%, showing that water ingestion during the interval replaces only 24.4% of the body fluids lost during the match. The assistants lost 0.79 (0.19) litre of water, equivalent to 1.05 (0.25)% of body weight. The referees showed a significant decrease in plasma volume of 4.99 (1.33)%. The assistants showed a non-significant increase in plasma volume. The reduction in plasma volume observed in the referees correlated significantly with total body water loss ( r = 0.9623). From these data, it is possible to predict that a dehydration of 1% reflects a reduction in plasma volume of nearly 2.5%. Conclusions: Referees are moderately dehydrated after a football match (2%), whereas assistants show a non-significant dehydration of 1% of their body weight.

Changes in fluid compartments and body composition in obese women after weight loss induced by gastric banding

Abstract: Background/Aims: Surgical gastric banding procedures induce considerable and rapid weight losses in obese subjects. Nevertheless changes in lean mass and body fluids following these surgical treatments are not well known. Methods: We studied 6 obese women aged 38–42 years, before, and 8 and 24 weeks after laparoscopic adjustable silicone gastric banding (LAP-BANDTM). Fat-free mass (FFM) and fat mass (FM) were investigated using dual energy X-ray absorptiometry (DEXA), while total body water (TBW) and extracellular water (ECW) were assessed by dilution methods. Results: The subjects showed a total weight loss of 16% of initial weight; the weight reduction was greater during the first 8 weeks. FFM decrease after 24 weeks was very limited and represented only 14% of the weight loss. The mean FFM changes per week were similar in the two periods of observation (0–8 and 8–24 weeks after LAP-BAND). TBW showed a global reduction of 2.2 ± 1.8 litres mainly due to a decline in intracellular water (ICW), while ECW remained constant during weight loss. As a consequence, the ECW/ICW ratio increased after LAP-BAND. Conclusion: LAP-BAND seems to achieve satisfactory weight losses while sparing FFM and causing only mild body fluid alterations.

Effects of growth hormone on fluid homeostasis. Clinical and experimental aspects.

Abstract: Regulation of body fluid homeostasis appears simple at first sight since daily sodium and water intake equals daily sodium and water output. The mechanisms enabling the body to excrete exactly the ingested and metabolically produced amounts of water and sodium are, however, complex and not completely understood. The factors regulating body fluid homeostasis may grossly be divided into humoral and physical factors. The former comprises among others the renin–angiotensin–aldosterone system (RAAS), arginine vasopressin (AVP), atrial natriuretic factor (ANF), and prostaglandins. The physical factors relate primarily to renal function and factors regulating osmotic pressure. Approximately 60% of body weight is water, which may be subdivided into intracellular volume (ICV) (40%) in which potassium and phosphate are the predominant cation and anion, respectively, and extracellular volume (ECV) (20%) dominated by sodium and chloride. ECV may further be subdivided into interstitial volume(15%) and plasma volume (PV) (5%) [1]. In principle ECV constitutes the internal environment, which is responsible for the transport of ions, nutrients and hormones vital to the cells. This term was introduced by the French physiologist, Claude Bernard, in 1885. The osmotic concentrations of ECV and ICV are equal under steady-state conditions, but any change result in an osmotic gradient and an immediate flux of water along this gradient until equilibrium is restored [2]. Hence a considerable passage of water occurs across the cell membrane, exemplified by the fact that the water content of an erythrocyte is exchanged 100 times per second without any netmovement of water [3]. Water passes mainly the cell membrane through protein channels, which in turn are influenced by osmotic differences generated by facilitated diffusion and active transport across the cell membrane. A normal subject ingests 2100ml water daily and synthesizes additionally 200ml by oxidation. Daily fluid output in a normal subject includes 700ml from the skin and lungs, 200ml from faeces, and sweat and a urinary output of 1400ml [4]. Between 5 and 10% of total body water is exchanged daily in healthy adults [1]. Total body water (TBW) is traditionally estimated by isotopic dilution. ECV and PV may also be estimated using this principle, whereas ICV assessment is calculated indirectly by combining measurements of TBW and ECV. The role of GH in this complex system is not fully established, but several reports suggest that it is important in body fluid regulation. More than 70 years ago anterior pituitary extracts were shown to induce fluid retention in rats [5] and two decades later GH-induced sodium and fluid retention was also demonstrated in man [6–8]. The sodiumand water-retaining effects of GH have subsequently been confirmed in several studies in normal man, in acromegalic patients and in GH-deficient patients [9–15]. Despite methodological heterogeneity most authors seem to agree that body fluid volume is decreased in GH-deficient adults and that GH treatment normalizes body fluid volume in these patients. There is also agreement that GH causes volume expansion, when administered in pharmacological doses to normal subjects and when secreted in excess in active acromegaly. Regarding the underlying mechanisms attention has focused on direct cellular action of GH [14] and a possible GH-induced stimulation of the renin–angiotensin– aldosterone system (RAAS) [8]. More recently other hormonal systems such as ANF [15], the prostaglandins [16], IGF-I [17], and nitric oxide [18] have been suggested to be involved. At present the sodium and fluidretaining effect of GH seems indisputable, whereas the underlying mechanisms appear to be diverse. www.elsevier.com/locate/ghir Growth Hormone & IGF Research 13 (2003) 55–74

Validation of air-displacement plethysmography for estimation of body fat mass in healthy elderly subjects.

Abstract: Air-displacement plethysmography (ADP) is a non-invasive method for body composition analysis that divides the body into fat-free mass (FFM) and fat mass (FM) (= 2 compartment model, 2C). It places low demands on subject performance and is therefore most convenient in the elderly. To validate ADP against dual energy X-ray absorptiometry (DEXA) and to compare it to a four-compartment model of body composition (4C; fat mass, total body water, bone mineral content and residual mass) in the elderly. Body composition was assessed by ADP, DEXA and bioelectrical impedance analysis (BIA) in 26 healthy elderly subjects (15 women, 11 men) aged 60–82 years. Despite a high correlation of %FM assessed by ADP and DEXA we observed significant differences between the results of these methods for both sexes (2.5 ±3.4%; bias ± SD). Deviations of %FMADP from %FMDEXA were dependent on bone mineral content (BMCDEXA) fraction of FFM. A low BMCDEXA was related to an overestimation of DEXA-derived %FM by ADP. There was a systematic bias between results from ADP and the 4C model. 76% of its variance was explained by the assumption of a fixed density of FFM. 96% of the variance in the density of FFM was explained by water content and only 4% by BMCDEXA of FFM. When compared to a 4C model, overestimation of %FMADP increases with increasing water fraction of FFM. Although there is a tendency for overestimation of %FMADP,ADP is a valid method for body composition measurement in the elderly. The bias in %FMADP is mainly related to water content of FFM and indicates that a correction factor for TBW may improve the accuracy of the ADP measurements in the elderly.