Bromide Dilution Research Articles

Body-water compartments measured by bio-electrical impedance spectroscopy in patients with chronic obstructive pulmonary disease

It was previously demonstrated that single frequency bio-electrical impedance (BIA) measurement at 50 kHz is a useful method to assess total body water (TBW) in patients with chronic obstructive pulmonary disease (COPD). In the present study it was examined whether bio-electrical impedance spectroscopy (BIS) could predict extracellular water (ECW) and improve the prediction of TBW in these patients. TBW and ECW (corrected bromide space) were measured by deuterium and bromide dilution. In 37 COPD patients prediction equations were obtained using BIS (5–500 kHz) measurements, and these were cross validated in a second group of 40 COPD patients. All patients were in a clinically stable condition. TBW predicted by BIS was not significantly different from actual TBW and demonstrated a comparable standard error of estimate (SEE) as found previously in healthy subjects (♂ correlation coefficient: r = 0.88, SEE: 2.3 L, ♀ r = 0.85, SEE: 2.9 L). Predicted ECW using BIS-measurements was not significantly different from measured ECW (♂ r = 0.75, SEE: 1.4 L, ♀ r = 0.73, SEE: 1.2 L), but the error in the prediction was relatively large and the correlation between predicted and actual ECW relatively low compared to most studies in healthy subjects. Predicted TBW using BIS was comparable to actual TBW, but presented no improvement of theprediction of TBW using BIA at 50 kHz and a patient specific regression equation. The error of the prediction of ECW by BIS limits the ability to predict fluid shifts in individual patients with clinically stable COPD.

Body composition and energy expenditure of patients with chronic cardiac failure.

Patients with acute cardiac failure have excess body water, and it is commonly assumed that this is also so in patients with stable chronic cardiac failure (CCF). To investigate this, we measured total body water (TBW) using stable isotope dilution and single-frequency bioelectrical impedance (BIA), and also extracellular volume (ECV) using bromide dilution in 12 patients with CCF and eight matched control subjects. TBW [kg(-1) bodyweight] was similar in the two groups [median 18O dilution 53.2% (range 46.5-57.1%) in patients vs. 54.8% (47.9-62.7) in control subjects; BIA 56.6% (42.7-73.1) vs. 58.0% (52.0-68.6)]. ECV was also similar in the two groups [0.25 Lkg(-1) (0.20-0.29) vs. 0.25 (0.19-0.35)]. There was a strong correlation between stable isotope and BIA measurements of TBW for all subjects (r = 0.76), but BIA overestimated TBW by a mean difference of 2.4 kg (limits of agreement of -4.1 kg to +8.9 kg). Body fat content was similar in the two groups, whether measured by skinfold anthropometry, whole-body densitometry or by 18O dilution. Resting energy expenditure (REE), calculated from indirect calorimetry, and total energy expenditure (TEE), calculated from the ratio of 2H to 18O elimination rate after drinking doubly labelled water, were also similar in the two groups. It is concluded that the patients with stable CCF in this study had normal ECV and TBW, and so excess body water did not account for their persistent symptoms.

Predicting body cell mass with bioimpedance by using theoretical methods: a technological review.

The body cell mass (BCM), defined as intracellular water (ICW), was estimated in 73 healthy men and women by total body potassium (TBK) and by bioimpedance spectroscopy (BIS). In 14 other subjects, extracellular water (ECW) and total body water (TBW) were measured by bromide dilution and deuterium oxide dilution, respectively. For all subjects, impedance spectral data were fit to the Cole model, and ECW and ICW volumes were predicted by using model electrical resistance terms RE and Rt in an equation derived from Hanai mixture theory, respectively. The BIS ECW prediction bromide dilution was r = 0.91, standard error of the estimate (SEE) 0.90 liter. The BIS TBW prediction of deuterium space was r = 0.95, SEE 1.33 liters. The BIS ICW prediction of the dilution-determined ICW was r = 0.87, SEE 1.69 liters. The BIS ICW prediction of the TBK-determined ICW for the 73 subjects was r = 0.85, SEE = 2.22 liters. These results add further support to the validity of the Hanai theory, the equation used, and the conclusion that ECW and ICW volume can be predicted by an approach based solely on fundamental principles.

Changes in Body Composition in HIV-infected (HIV+) Children with Growth Failure(GF). ♦ 464

In order to assess alterations in body composition in prepubertal children with HIV-associated GF, measurement of body fat (BF) and fat free mass (FFM) by dual energy x-ray absorptiometry; total body water (TBW) and extracellular water (ECW) by D2O and bromide dilution respectively; and body cell mass (BCM) by total body40 K (TBK) counting were performed. Eighteen HIV+ children with GF, 16 HIV+ children with normal growth, and 54 healthy children were studied.Table

Deuterium and Bromide Dilution, and Bioimpedance Spectrometry Independently Show That Growth Hormone-Deficient Adults Have an Enlarged Extracellular Water Compartment Related to Intracellular Water

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.

The prediction of total body water and extracellular water from bioelectric impedance in obese children.

To assess the reliability of bioelectric impedance analysis (BIA) for predicting total body water (TBW) and extracellular water (ECW) in obese children. Comparison of five prediction models based on: (i) body weight (Wt), (ii) the impedance (Z) index (ZI = height2/Z), (iii) the association of Wt and ZI, (iv) the body surface area (SA) to impedance ratio (SA:Z) and, (v) the body volume (V) to impedance ratio (V:Z). Thirty obese and 25 control children of 11.2 +/- 1.8 y of age. TBW and ECW were assessed by deuterium and bromide dilution; Z was measured at frequencies of 5,50 and 100 kHz. In controls, Wt explained 11% more variance of TBW than ZI (r2 = 0.977, SEE = 0.9 I, CV = 3.8%) and the association of Wt and ZI improved the prediction of TBW only slightly (r2 = 0.982, SEE = 0.8 I, CV = 3.5%). The SA:Z and V:Z indexes explained 6 and 33% less variance of TBW respectively as compared to Wt alone. In obese subjects, ZI explained 4% more variance of TBW than Wt (r2 = 0.914, SEE = 1.8 I, CV = 6.4%) and the SA:Z ratio was the most accurate predictor of TBW (r2 = 0.959, SEE = 1.2 I, CV = 4.4%). However, the increase in the explained variance of TBW associated to the use of the SA:Z ratio was of only 1% as compared to the association of ZI and Wt. The V:Z ratio explained 9% less of variance of TBW as compared to ZI. In both control and obese subjects, the association of Wt and ZI offered the best prediction of ECW (r2 = 0.807, SEE = 1.564 I and r2 = 0.826, SEE = 1.035 I, respectively). However, the values of CV were much higher in controls than in obese children (17.5% vs 8.4%) owing to their lower ECW and greater variability in ECW%. ZI was the most accurate predictor of TBW on the pooled sample (n = 55; r2 = 0.910, SEE = 1.932 I; CV = 7.4%). However, it was a poor predictor of ECW on the same sample owing to its high CV (n = 55; r2 = 0.866, SEE = 1.806 I, CV = 17.0%). The body surface area to impedance ratio is the most accurate predictor of TBW in obese children but the association of ZI and Wt may be of more interest when BIA is used to estimate both TBW and ECW. The impedance index offers a good prediction of TBW but not of ECW in children with different levels of fatness.

Analysis of body water compartments in relation to tissue depletion in clinically stable patients with chronic obstructive pulmonary disease

Tissue depletion often occurs in patients with chronic obstructive pulmonary disease (COPD), even in those that are weight-stable. Limited data are available, however, about changes in body water compartments in chronic wasting diseases such as COPD. The purpose of this study was to measure body composition in severe COPD patients with special attention to fat-free mass (FFM) depletion and the distribution of body water compartments. Total body water (TBW) and extracellular water (ECW) were measured by deuterium and sodium bromide dilution techniques, respectively, in 38 COPD patients (age: 65 +/- 9 y, forced expiratory volume in 1 s: 38 +/- 14% of predicted) in a stable clinical condition. FFM was calculated by assuming a hydration coefficient of 73%. Underweight patients [body mass index (BMI; in kg/m2) < or = 21] were characterized by a significantly lower percentage fat mass than normal-weight patients, but no significant difference was found in the ratio of ECW to intracellular water (ICW)(BMI < or = 21: 0.72 +/- 0.12, BMI > 21: 0.71 +/- 0.16; NS). When the study population was divided into depleted patients (FFM/height2 < or = 15 kg/m2) and nondepleted patients (FFM/height2 > 15 kg/m2), there was no significant difference in the percentage fat mass, but the ECW-ICW ratio was significantly higher in the depleted patients (0.78 +/- 0.16) than in the nondepleted patients (0.66 +/- 0.12, P < 0.05); this was most pronounced in women. In conclusion, it was found that COPD patients with extreme FFM wasting are characterized by an increased ECW-ICW ratio despite a relatively spared fat mass.

Water balance and acute mountain sickness before and after arrival at high altitude of 4,350 m.

The present study is a first attempt to measure water balance and its components at altitude by using labeled water and bromide dilution and relating the results with acute mountain sickness (AMS). Water intake, total water output, and water output in urine and feces were measured over a 4-day interval before and a subsequent 4-day interval after transport to 4,350 m. Total body water and extracellular water were measured at the start and at the end of the two intervals. There was a close relationship between energy intake and water intake, and the relationship was unchanged by the altitude intervention. Subjects developing AMS reduced energy intake and water intake cor respondingly. The increase in total body water (TBW) in subjects developing AMS was accompanied by a reduction in total water loss. They did not show the increased urine output, compensating for the reduced evaporative water loss at altitude. Subjects showed a significant increase in TBW after 4 days at altitude. Subjects with AMS showed the biggest shifts in extracellular water relative to TBW. In conclusion, fluid retention in relation to AMS is independent of a change in water requirements due to altitude exposure. Subjects developing AMS were those showing a fluid shift of at least 1 liter from the intracellular to the extracellular compartment or from the extracellular to the intracellular compartment.

Progressive cellular dehydration and proteolysis in critically ill patients

Summary Background According to a recent hypothesis, the profound loss of body protein that occurs in critically ill patients is triggered and maintained by cell shrinkage secondary to cellular dehydration. We tested this hypothesis by studying sequential changes in intracellular water, total body protein, total body potassium, and intracellular potassium in patients receiving intensive care for blunt trauma or sepsis. Methods Nine patients with multiple blunt trauma and 11 with severe sepsis were studied in an intensive care unit for 21 days. Intracellular water was measured in two ways—by subtraction of extracellular water (bromide dilution) from total body water (tritium dilution), and by bioimpedance spectroscopy. Total body protein was measured by whole-body neutron activation analysis and total body potassium by whole-body counting. Findings Over the study period intracellular water decreased by 15-20%, total body protein by 15%, and total body potassium by about 20%. Intracellular potassium concentration did not change, and was similar to that in healthy adult volunteers. In the trauma patients, sequential measurements of the ratio of potassium to protein in lost tissue indicated that cells were losing water in quantities greater than would be expected from protein losses. Interpretation The loss of protein and potassium from body stores in major trauma or sepsis is accompanied by progressive cellular dehydration. This insight opens up new therapeutic options for limiting the loss of body protein in critically ill patients.

Multifrequency bioelectric impedance measurements for predicting body water compartments in duchenne muscular dystrophy

Body hydration and extra- to intra-cellular water ratio (ECWICW) have been studied in 12 duchenne muscular dystrophy (DMD) patients and 15 healthy controls. Subjects underwent total body water (TBW) and extracellular water (ECW) assessment by deuterium and bromide dilution, respectively. Multifrequency bioelectric impedance analysis (MFBIA) was performed on all subjects with the aim to establish its accuracy in predicting TBW and ECW in DMD. Body hydration was lower (51.8 ± 2.8 vs 58.5 ± 5.9%, P < 0.01) and the ECW: ICW ratio higher (1.15 ± 0.25 vs 0.70 ± 0.23, P < 0.001) in DMD than in control subjects. Hence, control-generated formulae for predicting TBW and ECW from MFBIA gave inaccurate results in DMD subjects. Population-specific formulae were developed to obtain an accurate prediction of body water compartments in DMD patients.

Energetics of Water−Dodecyl Surfactant−Macrocyclic Compound Ternary Systems

Enthalpies of dilution and osmotic coefficients of sodium dodecyl sulfate (NaDS) and dodecyltrimethylammonium bromide (DTAB) in water + 18-crown-6 ether (CR) and water + β-cyclodextrin (CD) at a fixed cosolvent concentration were measured at 298 and 310 K, respectively, as functions of the surfactant concentration (mS). Enthalpies of transfer ΔH (W → W + S) of CR (0.03 m) from water to NaDS and DTAB aqueous solutions as functions of mS were also determined at 298 K. From the enthalpies of dilution the apparent (LΦ,S) and partial (L2,S) molar relative enthalpies of both surfactants were calculated. Despite CR forms inclusion complexes with the anionic surfactant only, the L2,S vs mS profiles are similar and the enthalpies of micellization are lower than those in water by about −5 kJ mol-1. In the case of CD as a cosolvent, the L2,S vs mS profile for DTAB is similar to that for NaDS in the postmicellar region but very different in the premicellar one. The trends in the premicellar region are discussed in te...

Physical activity, body composition and bone density in ballet dancers

The main purpose of the present study was to examine factors that affect bone mineral density (BMD) in female ballet dancers. Training history, Ca intake, body composition, total body BMD (TBMD) and site-specific BMD, and bone mineral content were described in twenty-four female ballet dancers (mean age 22.6 (SD 4.5) years). Training history was determined by questionnaires, Ca intake by 7 d dietary record, BMD and bone mineral content by dual-energy X-ray absorptiometry (DXA), total body water by 2H dilution, extracellular water by bromide dilution, body fat by underwater weighing (UWW; two-component model), DXA, and the four-component (4C) model. Dancers had a significantly lower body mass index (BMI 18.9 (SD 1.0) kg/m2) than controls (21.3 (SD 1.9) kg/m2), with significantly lower percentage body fat (17.4 (SD 3.9) v. 24.4 (SD 5.1)) but comparable fat-free mass. Mean TBMD (1.147 (SD 0.069) g/cm2) was significantly higher (6%) compared with that of a reference population. These high values could be attributed to the high BMD of legs and pelvis, the weight-bearing sites of the dancer's body. No relationship was found between age, start of ballet classes, period (years) of dancing, Ca intake, and BMD (total and site-specific). However, TBMD was positively related to BMI, and negatively related to the age of menarche. BMD of the legs was significantly related to BMI, and negatively related to the age of menarche. BMD of the legs was significantly related to daily period (h) of training. Depending on the method used the percentage body fat ranged from 16.4 (by DXA) to 18.3 by the 4C model. These differences were significantly related to the TBMD. Percentage body fat by the different methods was not significantly different, except for DXA and 4C model. The present study showed that, despite the factors that have a negative effect on BMD, such as low body mass and late menarche, BMD in female ballet dancers was relatively high. These high values were probably caused by high levels of weight-bearing physical activity.

Multi-frequency impedance for the prediction of extracellular water and total body water

The relationship between total body water (TBW) and extracellular water (ECW), measured by deuterium oxide dilution and bromide dilution respectively, and impedance and impedance index (height2/impedance) at 1, 5, 50 and 100 kHz was studied. After correction for TBW, ECW was correlated only with the impedance index at 1 and 5 kHz. After correction for ECW, TBW was best correlated with the impedance index at 100 kHz. The correlation of body-water compartments with impedance values obtained with modelling programs was lower than with measured impedance values. Prediction formulas for ECW (at 1 and 5 kHz) and TBW (at 50 and 100 kHz) were developed. The prediction errors for ECW and TBW were 1.0 and 1.7 kg respectively (coefficient of variation 5%). The residuals of both ECW and TBW were related to the ECW/TBW value. Application of the prediction formulas in a population, independently measured, revealed a slight overestimation of TBW and ECW, which could be largely explained by differences in the validation group in body-water distribution and in body build. The ratio of impedance at 1 kHz to impedance at 100 kHz was correlated with body-water distribution (ECW/TBW). The relation is however not strong enough to be useful as a predictor. It is concluded that an independent prediction of ECW and TBW, using impedance at low and high frequency respectively, is possible, but that the bias depends on the body-water distribution and body build of the measured subject.

Determination of intracellular water by multifrequency bioelectrical impedance.

Body composition was measured in 57 healthy males by 40K measurements and by multifrequency bioelectrical impedance. Intracellular resistance (Ricf) was calculated from the impedance values using the Cole-Cole model. From total body potassium, intracellular water (ICW) was calculated. In addition, in 14 subjects, total body water (TBW) and extracellular water (ECW) was measured using deuterium oxide dilution and bromide dilution, respectively. Prediction formulas from the literature from impedance at different frequencies were used to predict TBW and ECW, and ICW was calculated as the difference of predicted TBW and ECW. Predicted and measured values of TBW, ECW and ICW did not always show the same values as measured. Generally the ICW from potassium was well correlated with calculated ICW from impedance values, correlation coefficients varying from 0.68 to 0.79, depending on the used prediction formula. From the impedance index H2/Ricf, body weight and age, ICW from potassium was predicted with stepwise multiple regression. The prediction formula was ICW = 0.37065.H2/Ricf - 0.132.age + 0.105.weight + 12.2. The prediction error was 1.9 kg and the explained variance 0.69. The residuals of this prediction formula were dependent on the level of ICW as measured by potassium. The same phenomenon was observed when ICW was calculated as the difference of predicted TBW and ECW. The results show that multifrequency impedance is able to predict ICW, however, the prediction is influenced by body water distribution.

Distal versus proximal electrode placement in the prediction of total body water and extracellular water from multifrequency bioelectrical impedance.

In 48 normal weight subjects, 25 females and 23 males, body impedance was measured at multiple frequencies. Two different electrode placements were used, one the commonly used distal electrode placement, in which the source electrodes are on the dorsal sides of the hand and foot and the sensor electrodes are on ankle and wrist, and a second placement, in which the sensor electrodes are placed more proximally, at the knee and elbow. Theoretically a proximal electrode placement could result in more precise estimates of body water compartments. Total body water (TBW) and extracellular water (ECW) were determined using deuterium oxide dilution and bromide dilution, respectively. The aim of the study was to investigate whether proximal electrode placement results in a more precise estimation of TBW and ECW using multifrequency impedance analysis. Correlation coefficients of impedance and the impedance index stature2 /impedance) with TBW and ECW were not or were only slightly higher using proximal impedance values, resulting in slight improvement of the estimation error for TBW (0.13 kg) and ECW (0.04 kg). The differences between measured and predicted values (residuals) of TBW and ECW were not correlated with TBW and ECW, but they were correlated with body fat and body water distribution (ECW/TBW). These correlations did not differ between distal and proximal impedance measurements. It is concluded that proximal impedance measurements do not substantially improve the prediction of body water compartments. © 1995 Wiley-Liss, Inc.

Validity of Predicted Total Body Water and Extracellular Water Using Multifrequency Bioelectrical Impedance in an Ethiopian Population

Total body water (TBW) and extracellular water (ECW) were measured by deuterium oxide dilution and bromide dilution, respectively, in a group of 24 male and 20 female healthy Ethiopians, living in the capital Addis Ababa. Body weight, body height, skinfolds and total body impedance at 1 and at 100 kHz were also measured. TBW and ECW were predicted from impedance values at 1 and 100 kHz, respectively, using prediction equations developed in a Dutch adult population. ECW was overestimated by 1.3 +/- 1.0 kg (p < 0.05) and 0.6 +/- 0.8 kg (p < 0.05) in males and females, respectively. TBW was accurately predicted in males (0.1 +/- 1.9 kg, n.s.), but overestimated in females (1.0 +/- 1.3 p < 0.05). TBW/height and ECW/height were substantially lower in the Ethiopians compared to values recently published in Dutch and Italian adult subjects, indicating a different, more slender body build of the Ethiopians. After correcting for these differences in body build and for the slight differences in body water distribution (ECW/TBW), the differences between measured and predicted TBW and ECW decreased and were no longer significant. The results indicate that the validity of predicted body water from impedance depends on the body build of the subjects, which should be taken into account to avoid systematic errors when applying prediction formulas from a reference population to another population under study.

Relationship between nutrition, weight change, and fluid compartments in preterm infants during the first week of life

This study was conducted to investigate the redistribution of fluid compartments and to examine the factors contributing to the variability of early weight loss in premature infants. Fourteen preterm infants (mean +/- SD: birth weight, 1473 +/- 342 gm; gestational age, 30.7 +/- 2.4 weeks) were studied at 1 and 7 days of age. Total body water was measured by deuterium oxide dilution, extracellular volume by bromide dilution, and intracellular volume by the difference between total body water and extracellular volume. There were significant changes in body fluid distribution per concurrent weight from birth to age 1 week. Extracellular volume decreased by 11%, and intracellular volume increased by 8.5% with no change in total body water. Infants were then grouped according to postnatal weight loss (group 1 (n = 7) > 10% and group 2 (n = 7) < 5% of birth weight). In group 1 there was a significant loss of both weight (mean +/- SD: 15.6% +/- 3.7%) and extracellular volume (15.9% +/- 9% of birth weight), with no change in intracellular volume. In group 2 there was no significant weight loss (1.4% +/- 1.8%), but a significant loss of extracellular volume (13.0% +/- 5.4% of birth weight) and a significant increase in intracellular volume. Other differences between the groups were a lower energy intake in group 1 than in group 2 (mean +/- SD: 177 +/- 46 vs 269 +/- 45 kilojoules/kg per day; p < 0.005) and a higher physiologic stability index in group 1 (p < 0.05). We conclude that significant postnatal weight loss as a result of the contraction of the extracellular compartment occurs only in less stable infants whose energy intake is inadequate. With adequate energy intake, weight loss is minimal because of the expansion of the intracellular compartment, which may be related to the onset of growth.

Predicting total body water and extracellular fluid volumes from bioelectrical measurements of the human body.

Two biological impedance analyzers, a 50 kHz (RJL) and 20-100 kHz (BMA) instrument, and a total body electrical conductivity (TOBEC) instrument were used to estimate total body water (TBW), extracellular (ECF) and intracellular (ICF) fluid volumes by repeated measurements of 16 normal men (19-38 years old) to assess which, if any, would provide the best estimates. At 3-week intervals, TBW was determined by deuterium dilution, ECF by bromide dilution, ICF by difference (TBW-ECF) and lean body mass by density. Prediction equations were obtained by regression; predicted values for the body fluid volumes were calculated and the results were statistically evaluated. Both the TOBEC and the BMA provided rapid and reliable estimates for body fluid volumes with standard errors of the estimates of about 0.5-1.1 L for ECF, 1.0-1.8 L for TBW, and 1.0-1.3 L for ICF. Part of the error was attributable to standard tracer-dilution methods.

Body cell mass and leucine metabolism in cirrhosis

To investigate the influence of body composition on leucine metabolism, leucine turnover and oxidation were measured in six patients with stable biopsy-proven cirrhosis and in six age- and gender-matched controls using [1−14C]leucine tracer. Fat-free body mass and body cell mass were estimated from quantified measurements of H218O and bromide dilution. Although there were no differences in body weight, body surface area, body mass index, or fat-free body mass between study groups, body cell mass was decreased in cirrhotic patients (37.6 ± 0.1 vs. 46.4 ± 1.8 kg; P < 0.05). Leucine turnover did not significantly differ between groups in absolute values or when corrected for body weight or fat free body mass. However, cirrhotic patients had accelerated leucine turnover based on body cell mass (171.3 ± 8.2 vs. 143 ± 7.6 μmol · kg−1 · h−1; P < 0.03). Plasma leucine levels were decreased in cirrhosis (76.9 ± 9.7 vs. 117.9 ± 8.1 μmol/L; P < 0.001) and correlated with an expanded extracellular water compartment (r = −0.91; P < 0.001) and leucine oxidation (r = 0.91; P < 0.01) in the cirrhotic patients but not in the control subjects. These data indicate that body composition and fluid compartments are important factors influencing leucine metabolism in cirrhosis and should be considered in future studies.

Body cell mass and leucine metabolism in cirrhosis

To investigate the influence of body composition on leucine metabolism, leucine turnover and oxidation were measured in six patients with stable biopsy-proven cirrhosis and in six age- and gender-matched controls using [1-14C]leucine tracer. Fat-free body mass and body cell mass were estimated from quantified measurements of H2(18)O and bromide dilution. Although there were no differences in body weight, body surface area, body mass index, or fat-free body mass between study groups, body cell mass was decreased in cirrhotic patients (37.6 +/- 0.1 vs. 46.4 +/- 1.8 kg; P less than 0.05). Leucine turnover did not significantly differ between groups in absolute values or when corrected for body weight or fat free body mass. However, cirrhotic patients had accelerated leucine turnover based on body cell mass (171.3 +/- 8.2 vs. 143 +/- 7.6 mumol.kg-1.h-1; P less than 0.03). Plasma leucine levels were decreased in cirrhosis (76.9 +/- 9.7 vs. 117.9 +/- 8.1 mumol/L; P less than 0.001) and correlated with an expanded extracellular water compartment (r = -0.91; P less than 0.001) and leucine oxidation (r = 0.91; P less than 0.01) in the cirrhotic patients but not in the control subjects. These data indicate that body composition and fluid compartments are important factors influencing leucine metabolism in cirrhosis and should be considered in future studies. (Gastroenterology 1992 Apr;102(4 Pt 1):1325-33)