Nutritional status assessment and body composition analysis in pre-end stage renal disease patients

Relationship of Demographic, Dietary, and Clinical Factors to the Hydration Status of Patients on Peritoneal Dialysis

Objectives

To establish which clinical factors are associated with an increased proportion of extracellular fluid (ECF) in peritoneal dialysis (PD) patients.

Design

A single-center, cross-sectional analysis of 68 stable PD patients.

Method

Bioelectrical impedance measurements (RJL, single frequency; RJL Systems, Clinton, Michigan, USA) of resistance and reactance were used to determine the proportion of ECF comprising total body water (TBW) in 68 stable PD patients attending for routine clearance and membrane studies. All patients underwent detailed dietetic, adequacy, and membrane function tests. Blood pressure and antihypertensive requirements were also documented.

Results

Significant gender differences in body composition were observed, such that women had lower absolute TBW and fat-free mass per kilogram body weight, but proportionately more ECF for a given TBW, mean ECF:TBW 0.5 ± 0.03 versus 0.44 ± 0.05, p < 0.005. In view of this, patients were split into two groups, defined as “over-” or “normally” hydrated, either by using the single discriminator (median ECF:TBW = 0.47) for the whole population, which resulted in groups distorted by gender, or by using different discriminators according to gender (women: 0.49, men 0.45). In both analyses, overhydrated patients were older, had significantly lower plasma albumin, less total fluid removal per kilogram body weight, and higher peritoneal solute transport. When split by a single discriminator, the overhydrated patients had lower sodium removal and significantly less intracellular fluid volume due to an excess of women in this group who also had less residual function and had been on dialysis longer. Using gender-specific discrimination, overhydrated patients were heavier due to expansion of the ECF volume: 20 ± 4.1 L versus 16 ± 3.3 L, p < 0.001. Stepwise multivariate analysis found age ( p = 0.001), albumin ( p = 0.009), and fluid losses per kilogram body weight ( p = 0.025) to be independent predictors of gender-adjusted hydration status. Sodium intake did not vary according to hydration status.

Conclusion

Gender influences the assessment of hydration status of PD patients when employing bioimpedance, such that women tend to have more ECF. Taking this into account, age, albumin, and achieved fluid removal appear to be independently associated with hydration status, whereas peritoneal solute transport is not. Advice on dietary sodium should take account of hydration status and achievable losses.

Accuracy of direct segmental multi-frequency bioimpedance analysis in the assessment of total body and segmental body composition in middle-aged adult population

BACKGROUND & AIMS

Body composition measurement is a valuable tool for assessing nutritional status and physical fitness in a variety of clinical settings. Although bioimpedance analysis (BIA) can easily assess body composition, its accuracy remains unclear. We examined the accuracy of direct segmental multi-frequency BIA technique (DSM-BIA) in assessing different body composition parameters, using dual energy X-ray absorptiometry (DEXA) as a reference standard.

METHODS

A total of 484 middle-aged participants from the Leiden Longevity Study were recruited. Agreements between DSM-BIA and DEXA for total and segmental body composition quantification were assessed using intraclass correlation coefficients and Bland-Altman plots.

RESULTS

Excellent agreements were observed between both techniques in whole body lean mass (ICC female = 0.95, ICC men = 0.96), fat mass (ICC female = 0.97, ICC male = 0.93) and percentage body fat (ICC female = 0.93, ICC male = 0.88) measurements. Similarly, Bland-Altman plots revealed narrow limits of agreements with small biases noted for the whole body lean mass quantification but relatively wider limits for fat mass and percentage body fat quantifications. In segmental lean muscle mass quantification, excellent agreements between methods were demonstrated for the upper limbs (ICC female≥0.91, ICC men≥0.87) and lower limbs (ICC female≥0.83, ICC male≥0.85), with good agreements shown for the trunk measurements (ICC female = 0.73, ICC male = 0.70).

CONCLUSIONS

DSM-BIA is a valid tool for the assessments of total body and segmental body composition in the general middle-aged population, particularly for the quantification of body lean mass.

Body Composition Assessed by Impedance Changes Very Early with Declining Renal Graft Function

BACKGROUND

Kidney transplant (Tx) restores renal filtration, although it does not achieve the function of two native kidneys, and with time it may variably involute back to chronic renal failure. We hypothesized that bioelectrical impedance analysis (BIA) might highlight differences for body compartments among Tx with different filtration rates, and we compared them with healthy controls.

METHODS

38 Tx patients (25 males, 13 females) were studied at 75.9 +/- 37.8 months postsurgery and divided into three groups: good creatinine clearance (CrCl, ml/min/1.73 m2; > 65.0), borderline (35.0 < CrCl < 60.0) and bad (CrCl < 35.0). BIA was assessed three times in a year. Total body water, extracellular water (ECW), intracellular water (ICW), Na:K exchange rate (Nae:Ke) and phase angle were studied. Healthy (n = 11) and hemodialysis (n = 11) groups were also studied.

RESULTS

BIA showed no differences between healthy controls and good Tx while both borderline and bad Tx presented a significantly higher ECW and lower ICW than either good Tx or normal controls. Only good CrCl was different from predialysis.

CONCLUSIONS

A good kidney graft manages to restore and maintain normal body composition, even with potential disturbances brought about by steroids and cyclosporine. With mild renal dysfunction a change in body compartments was observed, moving towards the composition of that with chronic renal failure patients.

Prospective nutritional surveillance using bioelectrical impedance in chronic kidney disease patients

Malnutrition is a well-known risk factor influencing survival in chronic maintenance dialysis patients. Chronic kidney disease (CKD) patients are also predisposed to malnutrition because of dietary restrictions and the catabolic effects of uremia. Therefore, a significant degree of malnutrition may be present before the initiation of renal replacement therapy. We consequently initiated a prospective evaluation of subjects attending the CKD clinic, where all patients are seen by a renal dietitian and nutritional, biochemical, and bioimpedance parameters are measured every 3 months. A total of 40 patients have completed 9 months of follow-up and are the subject of this report. Their mean age is 65 +/- 12 years, 48% female, 68% black, and 58% diabetic patients. The glomerular filtration rate did not change during follow-up (36 +/- 12 versus 34 +/- 14 mL/min/1.72 m 2 , at baseline and 9 months, respectively). Similarly, no differences between baseline and 9 months were noted in weight (88.0 +/- 20.3 versus 86.8 +/- 18.7 kg, respectively) or body mass index (30.6 +/- 5.8 versus 30.2 +/- 5.4 kg/m 2 , respectively). In addition, no differences between baseline and 9 months were noted in total body water (44.4 +/- 11.4 versus 44.6 +/- 10.8 L, respectively), body cell mass (25.3 +/- 7.4 versus 25.2 +/- 7.0 kg, respectively), and fat-free mass (59.2 +/- 16.6 versus 59.4 +/- 15.7 kg, respectively). The bioimpedance vector decreased with time in 25 subjects (62%), indicating a state of overhydration. Subjects were further analyzed by vector category. Body cell mass did not change in either group. As expected, total body water increased in the group with a decreasing bioimpedance vector. Because body cell mass did not increase, the greater total body water reflected an increase in extracellular volume (edema). In the group with stable vectors, no changes were noted with time in weight or total body water. These results indicate that CKD patients with stable renal function following a judicious dietary protein intake (0.6 to 0.8 g/kg normalized body weight/day) have no loss of body cell mass or fat-free mass over a 9-month period. Of note, a high proportion of patients (62%) developed clinically unrecognized fluid retention, which is promptly identified by a decreasing bioimpedance vector.

Bioimpedance analysis highlights changes in body composition at the early stages of impairment of kidney transplant function

OBJECTIVE

Kidney transplantation restores renal filtration, although it does not achieve the function of 2 native kidneys, and with time it may involute back to chronic renal failure. We hypothesized that bioelectrical impedance analysis (BIA) might highlight differences for body compartments among kidney transplants (Tx) with different filtration rates.

METHODS

Thirty transplantation patients (19 male, 11 female) were studied at 62.4+/-26.6 months postsurgery and were divided into 3 groups: good creatinine clearance (crCl, mL/min/1.73 m2; >65.0), borderline (35.0<crCl<60.0), and bad (crCl <35.0). BIA was assessed 3 times in 1 year. Total body water, extracellular water (ECW), intracellular water (ICW), Na:K exchangeable ratio (Nae:Ke), and phase angle were studied. Healthy (n=11) and hemodialysis (n=11) groups were studied as well.

RESULTS

BIA showed no differences between healthy controls and good Tx, whereas both borderline and bad Tx presented a significantly higher ECW and lower ICW than either good Tx or normal controls. Only good crCl was different from predialysis.

CONCLUSIONS

A good graft kidney manages to restore and maintain normal body composition, whereas with mild renal dysfunction a change in body compartments was observed, moving toward the body water composition of chronic renal failure patients.

Body composition and cardiovascular risk factors in pretransplant hemodialysis patients

BACKGROUND

Obesity, hyperlipemia and cardiovascular complications contribute to a significant proportion of morbidity and mortality of renal transplant patients and have negative effects on renal survival. Aim of the present study was to evaluate the main abnormalities in body composition and the prevalence of some cardiovascular risk factors in a population of hemodialyzed (HD) patients awaiting renal transplantation.

METHODS

We studied 151 HD patients, all included in a waiting list for renal transplantation, 97 males and 54 females, with mean age 47.4+/-12 years. Patients were divided into three groups according to their body mass index (BMI) (kg/m2): 18.5 to 24.9 (normoweight, NW); 25.0 to 29.9 (overweight, OW); > or =30 (obese, OB). The body composition measurements were obtained the day after the mid-week HD session using bioelectrical impedance analysis (BIA).

RESULTS

We found that 47 patients were NW (31%), while 56 were OW (37%), and 48 were OB (32%). BIA-measured body cell mass was (BCM) significantly increased in the OW as compared with the NW group (P<0.001), but, of note, no significant difference was found in OB group in comparison with the OW. Total cholesterol and triglycerides plasma levels were significantly elevated in OW and OB patients with respect to NW (P<0.05) and an increased prevalence of diabetes was seen in OB patients (NW: 6%, OW: 5%, OB: 12%).

CONCLUSIONS

These data show that a large proportion of patients awaiting renal transplant are overweight or obese and a consistent part of them have other cardiovascular risk factors associated. Furthermore, obese HD patients have a BCM lower than predicted on the basis of BMI and show an altered metabolic profile. A better understanding of the characteristics of patients included in the renal transplant waiting list is crucial in order to design prospective studies that aim to define the proper risk profile for the selection of patients.

Body composition analysis by bioelectrical impedance in chronic maintenance dialysis patients: comparisons to the National Health and Nutrition Examination Survey III

OBJECTIVE

To compare bioelectrical impedance analysis derived parameters in chronic maintenance dialysis patients to those obtained in National Health and Nutrition Examination Survey (NHANES) III.

DESIGN

Cross-sectional nutritional surveillance study.

SETTING

Hospital-based, not-for-profit chronic maintenance dialysis center.

PATIENTS

A total of 913 chronic maintenance dialysis patients and a subset of 10,263 subjects from NHANES III who underwent bioelectrical impedance analysis. Independent (Predictor) Variables: Bioelectrical impedance parameters including resistance, reactance, phase angle, and total body capacitance.

MAIN OUTCOME MEASURES

Total body water, intracellular and extracellular water, body cell mass, fat free mass, fat mass.

RESULTS

Relative to NHANES III, end-stage renal disease patients have lower resistance (3%), reactance (26%), phase angle (28%); and intracellular water (9%) values, whereas extracellular water content is 17% higher (P < .001). In addition, body cell mass, fat free mass, and fat mass were lower in end-stage renal disease patients when compared with NHANES III subjects (9%, 3%, and 12%, respectively; P < .001).

CONCLUSIONS

End-stage renal disease patients have a lower tissue mass than the general population and remain in a state of overhydration while on chronic maintenance dialysis therapy.

Body mass index as a predictor of continued survival in older chronic dialysis patients

OBJECTIVE

To investigate the contribution of body mass index (BMI) to mortality over 11 years of follow-up in a prevalent sample of dialysis patients aged 60+.

DESIGN

Multivariate Cox proportional hazards regression analysis.

SETTING

Multicenter stratified random sample of black and white older chronic dialysis patients in a southeastern state.

SUBJECTS

316 patients on hemodialysis (HD) and peritoneal dialysis (PD).

MAIN OUTCOME MEASURE

Continued survival from baseline interview in 1988 to June 1999.

RESULTS

Adjusting for age, primary diagnosis of diabetes, cardiovascular comorbidity, HD/PD therapy, and patient-reported functional impairment, the interaction of baseline BMI with race and gender was associated with older patients' risk of mortality. Black females, black males, and white males with higher BMI had a reduced risk of mortality, while no protective effect of higher BMI was found for white females. Patients with cardiovascular comorbidity and greater functional impairment at baseline had increased mortality risk. BMI was not significantly correlated with serum albumin or functional impairment.

CONCLUSION

BMI, a simple anthropometric measure that provides a marker of nutritional status, interacts with race and gender to predict long-term survival in older dialysis patients. The association of survival with dialysis adequacy, nutritional indicators, and cardiovascular status in black and white dialysis patients is an important area of study.