Comparison of three methods for the determination of body fat in patients on long-term hemodialysis therapy

Muscle fat infiltration in chronic kidney disease: a marker related to muscle quality, muscle strength and sarcopenia

Muscle fat infiltration (MFI) also known as myosteatosis refers to any deposit of lipids found in the skeletal muscle. MFI is preferably assessed by image-based methods like computed tomography (CT), magnetic resonance image (MRI) and ultrasound, normally from muscle groups located in the legs, arms and in the trunk. MFI is understood as a marker of muscle quality, where a muscle with higher fat deposition has lower contraction power and capacity to produce force per unit of muscle mass. This concept supports the hypothesis that a decrease in muscle strength is not always explained by a decrease in muscle mass, but also by other factors, including lipid deposition in the muscle. In the general population, MFI is associated with older age, physical inactivity and with insulin resistance and inflammation. In chronic kidney disease (CKD), MFI has been associated with a decrease in muscle strength and impaired muscle quality as well as with metabolic abnormalities, cardiovascular disease and increased mortality. Interventions aimed at reducing MFI in CKD are incipient, but it seems that guided exercise can ameliorate muscle quality in patients on hemodialysis. The aim of this narrative review about MFI in CKD is to draw attention to a still not often addressed complication in CKD. We conclude that more studies are warranted to investigate mechanisms and factors promoting MFI in CKD. Thus, clinical trials aimed at understanding the type, frequency and intensity of exercise that can diminish MFI and improve the clinical condition of the patients are needed.

Significance of Adipose Tissue Maintenance in Patients Undergoing Hemodialysis

In the general population, obesity is known to be associated with adverse outcomes, including mortality. In contrast, high body mass index (BMI) may provide a survival advantage for hemodialysis patients, which is known as the obesity paradox. Although BMI is the most commonly used measure for the assessment of obesity, it does not distinguish between fat and lean mass. Fat mass is considered to serve as an energy reserve against a catabolic condition, while the capacity to survive starvation is also thought to be dependent on its amount. Thus, fat mass is used as a nutritional marker. For example, improvement of nutritional status by nutritional intervention or initiation of hemodialysis is associated with an increase in fat mass. Several studies have shown that higher levels of fat mass were associated with better survival in hemodialysis patients. Based on body distribution, fat mass is classified into subcutaneous and visceral fat. Visceral fat is metabolically more active and associated with metabolic abnormalities and inflammation, and it is thus considered to be a risk factor for cardiovascular disease and mortality. On the other hand, subcutaneous fat has not been consistently linked to adverse phenomena and may reflect nutritional status as a type of energy storage. Visceral and subcutaneous adipose tissues have different metabolic and inflammatory characteristics and may have opposing influences on various outcomes, including mortality. Results showing an association between increased subcutaneous fat and better survival, along with other conditions, such as cancer or cirrhosis, in hemodialysis patients have been reported. This evidence suggests that fat mass distribution (i.e., visceral fat and subcutaneous fat) plays a more important role for these beneficial effects in hemodialysis patients.

Can skinfold thickness equations be substituted for bioimpedance analysis in children?

OBJECTIVE

The aim of the present study was to evaluate the agreement between the most used skinfold thickness equations with multi-frequency bioimpedance analysis in the prediction of body fat levels in children.

METHOD

A cross-sectional study of healthy Brazilian community-dwelling individuals. The anthropometric assessment included height, body mass, arm circumference, and waist circumference. The percentage of body fat was obtained by measuring skinfold thickness equations and using bioimpedance analysis, and skinfold thickness was measured using a scientific skinfold caliper. Bland-Altman plot analysis was used to verify the agreement between the methods.

RESULTS

There were 439 children and adolescents evaluated, with a mean age of 11.6±3.7 years. The mean body fat by bioimpedance analysis was 22.8%±10.4%, compared to 22.4%±8.8% by Slaughter (1), 20.4%±9.2% by Slaughter (2), 19.6%±4.4% by Goran, and 24.7%±10.0% by Huang equations. Bland-Altman plot analysis revealed limits of agreement greater than 8% between the bioimpedance analysis approach and equations, exceeding the clinically acceptable limit predefined a priori. None of the equations had good agreement with bioimpedance analysis.

CONCLUSION

It was concluded that skinfold thickness and bioimpedance analysis should not be used interchangeably in children and adolescents.

Body composition parameters can better predict body size dissatisfaction than body mass index in children and adolescents

PURPOSE

Recent studies suggest that body mass index is not a reliable enough measurement for body composition in individuals, particularly in older and younger people. However, most research on body image has used the body mass index (BMI) as a physiological predictor of body satisfaction, particularly in children. The aim of this study was to investigate whether body composition is a better predictor of body size dissatisfaction in children than BMI.

METHODS

This is a cross-sectional study. Healthy children and adolescents aged 5-19 years, sex male and female, were recruited using a convenience sample in Brazil. BMI was measured according to the international standardization method and body composition was measured by bioelectrical impedance analysis (BIA) with a portable device model (BIA InBodyS10 multi-frequency, USA). Body size dissatisfaction was assessed using the Kakeshita's Figure Rating Scale for Brazilian Children. Data were analyzed with logistic regression analysis.

RESULTS

A total of 547 participants were evaluated, including 54% females and 67% Caucasian, with a mean age of 11.4 ± 3.8 years. The mean BMI was 20.5 ± 4.6 kg/m², and the mean percentages of fat and lean mass were 23.01 ± 10.59% and 72.84 ± 10.03%, respectively. In the multivariable model, only body composition was significantly associated with body size dissatisfaction (odds ratio: 1.849 (1.085-3.149, p = 0.024) and 1.828 (1.043-3.202, p = 0.035), respectively).

CONCLUSIONS

Body composition measures can better predict body size dissatisfaction in children and adolescents than BMI. This result may be relevant for the design of future studies on physiological indicators and body satisfaction.

LEVEL OF EVIDENCE

Level V, cross-sectional study.

KDOQI Clinical Practice Guideline for Nutrition in CKD: 2020 Update

The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) has provided evidence-based guidelines for nutrition in kidney diseases since 1999. Since the publication of the first KDOQI nutrition guideline, there has been a great accumulation of new evidence regarding the management of nutritional aspects of kidney disease and sophistication in the guidelines process. The 2020 update to the KDOQI Clinical Practice Guideline for Nutrition in CKD was developed as a joint effort with the Academy of Nutrition and Dietetics (Academy). It provides comprehensive up-to-date information on the understanding and care of patients with chronic kidney disease (CKD), especially in terms of their metabolic and nutritional milieu for the practicing clinician and allied health care workers. The guideline was expanded to include not only patients with end-stage kidney disease or advanced CKD, but also patients with stages 1-5 CKD who are not receiving dialysis and patients with a functional kidney transplant. The updated guideline statements focus on 6 primary areas: nutritional assessment, medical nutrition therapy (MNT), dietary protein and energy intake, nutritional supplementation, micronutrients, and electrolytes. The guidelines primarily cover dietary management rather than all possible nutritional interventions. The evidence data and guideline statements were evaluated using Grading of Recommendations, Assessment, Development and Evaluation (GRADE) criteria. As applicable, each guideline statement is accompanied by rationale/background information, a detailed justification, monitoring and evaluation guidance, implementation considerations, special discussions, and recommendations for future research.

Protein and Energy Depletion in Chronic Hemodialysis Patients: Clinical Applicability of Diagnostic Tools

Protein and energy depletion states are common and associated with increased morbidity and mortality in chronic hemodialysis (CHD) patients. Therefore, proper use of diagnostic tools to assess depleted states in CHD patients is critical. Assessment of protein and energy status can be done by an array of methodologies that include simple estimates of the visceral and somatic pools of protein to more refined techniques to measure protein and energy balance. The nutritional and metabolic derangements in the CHD population are highly complex and can be confounded by multiple comorbidities and fluid shifts between body compartments. Therefore, assessment of protein and energy status in CHD patients requires a wide range of methodologies that not only identify depleted states but also monitor nutrition therapy and predict clinical outcome. Most important, these methods require cautious and individualized interpretation in order to minimize the interference of comorbid conditions frequently observed in the CHD population. Currently, there is not a single method that can be considered the gold standard for assessment of protein and energy status in CHD patients. Therefore, a combination of methods is recommended. In this review, we describe available methods to assess protein and energy status, with special considerations pertaining to CHD patients.

Concordance of obesity classification between body mass index and percent body fat among school children in Saudi Arabia

Background

In Saudi Arabia, where childhood obesity is a major public health issue, it is important to identify the best tool for obesity classification. Hence, we compared two field methods for their usefulness in epidemiological studies.

Methods

The sample consisted of 874 primary school (grade I-IV) children, aged 6–10 years, and was obtained through a multi-stage random sampling procedure. Weight and height were measured, and BMI (kg/m²) was calculated. Percent body fat was determined with a Futrex analyzer that uses near infrared reactance (NIR) technology. Method specific cut-off values were used for obesity classification. Sensitivity, specificity, positive and negative predictive values were determined for BMI, and the agreement between BMI and percent body fat was calculated.

Results

Compared to boys, the mean BMI was higher in girls whereas the mean percent body fat was lower (p-values <0.0001). According to BMI, the prevalence of overweight or obesity was significantly higher in girls (34.3% vs. 17.3%); as oppose to percent body fat, which was similar between the sexes (6.6% vs. 7.0%). The sensitivity of BMI to classify overweight or obesity was high (boys =93%, girls = 100%); and its false-positive detection rate was also high (boys = 63%, girls = 81%). The agreement rate was low between these two methods (boys = 0.48, girls =0.24).

Conclusions

There is poor agreement in obesity classification between BMI and percent body fat, using NIR method, among Saudi school children.

Monitoring intracellular, interstitial, and intravascular volume changes during fluid management procedures

The bioimpedance spectroscopic (BIS) analytical algorithm described in this report allows for the non-invasive measurement of intravascular, interstitial, and intracellular volume changes during various fluid management procedures. The purpose of this study was to test clinical use feasibility and to demonstrate the validity of the BIS algorithm in computing compartmental volume shifts in human subjects undergoing fluid management treatment. Validation was performed using volume changes recorded from 20 end stage renal disease patients. The validation procedure involved mathematically deriving post hoc hematocrit profiles from the BIS data-generated fluid redistribution time profiles. These derived hematocrit profiles were then compared to serial hematocrit values measured simultaneously by a CritLine(®) monitor during 60 routine hemodialysis sessions. Regression and Bland-Altman analyses confirm that the BIS algorithm can be used to reliably derive the continuous and real-time rates of change of the compartmental fluid volumes. Regression results yielded a R (2) > 0.99 between the two measures of hematocrit at different times during dialysis. The slopes of the regression equations at the different times were nearly identical, demonstrating an almost one-to-one correspondence between the BIS and CritLine(®) hematocrits. Bland-Altman analysis show that the BIS algorithm can be used interchangeably with the CritLine(®) monitor for the measurement of hematocrit. The present study demonstrates for the first time that BIS can provide real-time continuous measurements of compartmental intravascular, interstitial and intracellular fluid volume changes during fluid management procedures when used in conjunction with this new algorithm.

Body fat does not affect venous bubble formation after air dives of moderate severity: theory and experiment

For over a century, studies on body fat (BF) in decompression sickness and venous gas embolism of divers have been inconsistent. A major problem is that age, BF, and maximal oxygen consumption (Vo2max) show high multicollinearity. Using the Bühlmann model with eight parallel compartments, preceded by a blood compartment in series, nitrogen tensions and loads were calculated with a 40 min/3.1 bar (absolute) profile. Compared with Haldanian models, the new model showed a substantial delay in N2 uptake and (especially) release. One hour after surfacing, an increase of 14-28% in BF resulted in a whole body increase of the N2 load of 51%, but in only 15% in the blood compartment. This would result in an increase in the bubble grade of only 0.01 Kisman-Masurel (KM) units at the scale near KM = I-. This outcome was tested indirectly by a dry dive simulation (air breathing) with 53 male divers with a small range in age and Vo2max to suppress multicollinearity. BF was determined with the four-skinfold method. Precordial Doppler bubble grades determined at 40, 80, 120, and 160 min after surfacing were used to calculate the Kisman Integrated Severity Score and were also transformed to the logarithm of the number of bubbles/cm(2) (logB). The highest of the four scores yielded logB = -1.78, equivalent to KM = I-. All statistical outcomes of partial correlations with BF were nonsignificant. These results support the model outcomes. Although this and our previous study suggest that BF does not influence venous gas embolism (Schellart NAM, van Rees Vellinga TP, van Dijk FH, Sterk W. Aviat Space Environ Med 83: 951-957, 2012), more studies with different profiles under various conditions are needed to establish whether BF remains (together with age and Vo2max) a basic physical characteristic or will become less important for the medical examination and for risk assessment.

Sex-specific association of anthropometric measures of body composition with arterial stiffness in a healthy population

Background

Anthropometric measures of body composition and arterial stiffness are commonly used as indicators of cardiovascular risk. Little is known, however, about the association of the anthropometric measures with arterial stiffness, especially in a healthy, generally non-obese population.

Material/Methods

In a sample of 352 healthy subjects (200 premenopausal women), 3 arterial stiffness indices were analyzed (pulse wave velocity, augmentation index and central systolic blood pressure) in relation to 5 anthropometric measures of body composition (body mass index – BMI, body fat percentage by skinfold measurements –%BF, waist circumference – WC, waist-hip ratio – WHpR, and waist-height ratio – WHtR). Data were analyzed using correlation and regression analyses, with adjustment for the following confounders: age, blood pressures, height, heart rate, blood lipids and smoking.

Results

Most correlations between anthropometric measures and arterial stiffness indices were significant and positive in both sex groups (r=0.14–0.40, P<0.05). After adjustment for confounding effects, BMI, WC and WHtR remained significant (but inverse) predictors of arterial stiffness (β from −0.06 to −0.16; P<0.05) in the females, while in the males BMI was the only measure inversely predicting arterial stiffness (β from −0.09 to −0.13; P<0.05).

Conclusions

Measures of body composition are weak and inverse predictors of arterial stiffness and their influence is sex-dependent. BMI, WC and WHtR were key predictors of arterial stiffness in the females, while BMI was the principal predictor in the males. The associations of anthropometric measures with arterial stiffness are strongly and differently confounded by various factors that have to be taken into account when explaining results of similar studies.

Bioelectrical impedance analysis and skinfold thickness sum in assessing body fat mass of renal dialysis patients

OBJECTIVE

In chronic renal failure patients under hemodialysis (HD) treatment, the availability of simple, safe, and effective tools to assess body composition enables evaluation of body composition accurately, in spite of changes in body fluids that occur in dialysis therapy, thus contributing to planning and monitoring of nutritional treatment. We evaluated the performance of bioelectrical impedance analysis (BIA) and the skinfold thickness sum (SKF) to assess fat mass (FM) in chronic renal failure patients before (BHD) and after (AHD) HD, using air displacement plethysmography (ADP) as the standard method.

DESIGN

This single-center cross-sectional trial involved comparing the FM of 60 HD patients estimated BHD and AHD by BIA (multifrequential; 29 women, 31 men) and by SKF with those estimated by the reference method, ADP. Body fat-free mass (FFM) was also obtained by subtracting the total body fat from the individual total weight.

RESULTS

Mean estimated FM (kg [%]) observed by ADP BHD was 17.95 ± 0.99 kg (30.11% ± 1.30%), with a 95% confidence interval (CI) of 16.00 to 19.90 (27.56 to 32.66); mean estimated FM observed AHD was 17.92 ± 1.11 kg (30.04% ± 1.40%), with a 95% CI of 15.74 to 20.10 (27.28 to 32.79). Neither study period showed a difference in FM and FFM (for both kg and %) estimates by the SKF method when compared with ADP; however, the BIA underestimated the FM and overestimated the FFM (for both kg and %) when compared with ADP.

CONCLUSION

The SKF, but not the BIA, method showed results similar to ADP and can be considered adequate for FM evaluation in HD patients.

Comparação de métodos de avaliação da gordura corporal total e sua distribuição

OBJETIVO: Comparar dois métodos de avaliação da gordura corporal total e sua distribuição. MÉTODOS: Estudo transversal, aninhado a uma coorte. Em amostra de 62 mulheres realizou-se avaliação do estado nutricional, incluindo a gordura corporal (GC) total obtida pelo somatório de dobras cutâneas (ΣDC) e bioimpedância (BIA). Mensurou-se a distribuição da gordura visceral por ultrassonografia (USG) (espessura de gordura intra-abdominal-EIA) e circunferência da cintura (CC). Foram calculados o coeficiente de correlação de concordância (CCC) e o coeficiente de determinação (r²). RESULTADOS: A média de idade das pacientes foi de 48,19 (8,99) anos. Observou-se 36 (58,06%) mulheres com a CC muito aumentada e 42 (67,74%) com GC aumentada. Identificou-se moderada concordância (r² = 0,42; CCC = 0,59; p < 0,01), entre os métodos avaliados para determinação da gordura corporal (%) e uma ótima concordância (r² = 0,90; CCC = 0,91; p < 0,01) para a gordura corporal (kg), avaliadas por BIA e ΣDC. A comparação entre a CC e EIA (USG) evidenciou uma moderada concordância (r² = 0,49; p < 0,01), entre os métodos. CONCLUSÕES: Evidenciou-se moderada concordância na avaliação da gordura corporal total (%) e ótima concordância na avaliação da gordura corporal (kg), entre os métodos utilizados. Identificou-se uma moderada concordância entre os métodos de distribuição da gordura corporal.

Mid-arm muscle circumference and quality of life and survival in maintenance hemodialysis patients

BACKGROUND AND OBJECTIVES

Maintenance hemodialysis (MHD) patients with larger body or fat mass have greater survival than normal to low mass. We hypothesized that mid-arm muscle circumference (MAMC), a conveniently measured surrogate of lean body mass (LBM), has stronger association with clinical outcomes than triceps skinfold (TSF), a surrogate of fat mass.

DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS

The associations of TSF, MAMC, and serum creatinine, another LBM surrogate, with baseline short form 36 quality-of-life scores and 5-year survival were examined in 792 MHD patients. In a randomly selected subsample of 118 subjects, LBM was measured by dual-energy x-ray absorptiometry.

RESULTS

Dual-energy x-ray absorptiometry-assessed LBM correlated most strongly with MAMC and serum creatinine. Higher MAMC was associated with better short form 36 mental health scale and lower death hazard ratios (HRs) after adjustment for case-mix, malnutrition-inflammation-cachexia syndrome, and inflammatory markers. Adjusted death HRs were 1.00, 0.86, 0.69, and 0.63 for the first to fourth MAMC quartiles, respectively. Higher serum creatinine and TSF were also associated with lower death HRs, but these associations were mitigated after multivariate adjustments. Using median values of TSF and MAMC to dichotomize, combined high MAMC with either high or low TSF (compared with low MAMC/TSF) exhibited the greatest survival, i.e., death HRs of 0.52 and 0.59, respectively.

CONCLUSIONS

Higher MAMC is a surrogate of larger LBM and an independent predictor of better mental health and greater survival in MHD patients. Sarcopenia-correcting interventions to improve clinical outcomes in this patient population warrant controlled trials.

Comparing body composition assessment tests in long-term hemodialysis patients

BACKGROUND

Protein-energy wasting is common in chronic kidney disease and is associated with decreases in body muscle and fat stores and poor outcomes. The accuracy and reliability of field methods to measure body composition is unknown in this population.

STUDY DESIGN

Cross-sectional observational study.

SETTING & PARTICIPANTS

118 maintenance hemodialysis patients were seen at the General Clinical Research Center at Harbor-UCLA Medical Center, Torrance, CA.

INDEX TESTS

Triceps skinfold, near-infrared interactance, and bioelectrical impedance analysis using the Segal, Kushner, and Lukaski equations.

REFERENCE TEST

Dual-energy x-ray absorptiometry (DEXA).

RESULTS

Participants (42% women, 52% with diabetes, 40% African Americans, and 38% Hispanics) were aged 49.4 +/- 11.5 (mean +/- SD) years, and had undergone dialysis therapy for 41.1 +/- 32.9 months. Body mass index was 27.0 +/- 6.0 kg/m(2). Using DEXA as the reference test, the bioelectrical impedance analysis-Kushner equation, triceps skinfold, and near-infrared interactance were most accurate of the index tests in estimating total-body fat percentage, whereas bioelectrical impedance analysis-Segal equation and bioelectrical impedance analysis-Lukaski equation overestimated total body fat percentage. Bland-Altman analyses and difference plots showed that bioelectrical impedance analysis-Kushner and near-infrared interactance were most similar to the reference test. Bioelectrical impedance analysis-Kushner, triceps skinfold, and near-infrared interactance had the smallest mean differences from DEXA, especially in women (1.6%, 0.7%, and 1.2%, respectively). Similar results were observed in African American participants (n = 47).

LIMITATIONS

Measurements were performed 1 day after a hemodialysis treatment, leading to more fluid retention, which may have affected the reference and index tests differently.

CONCLUSIONS

Using DEXA as the reference test, both near-infrared interactance and bioelectrical impedance analysis-Kushner method yield more consistent estimates of total body fat percentage in maintenance hemodialysis patients compared with the other index tests. Near-infrared interactance is not affected by skin color. Field methods with portable devices may provide adequate precision.

[Assessment and follow-up of nutritional status in hemodialysis patients]

Malnutrition is common among hemodialysis patients and is associated with increased risk of morbidity and mortality. Early recognition and treatment of malnutrition is essential to improve the outcome of these patients. Nutritional status may be assessed by several clinical markers including dietary records, anthropometric measurements and subjective global assessment. Among biochemical parameters, albumin is the most commonly used and prealbumin the most useful. Protein catabolic rate reflects dietary protein intake. Body composition analysis by bioelectrical impedance analysis or better by dual energy X-ray absorptiometry offers a reasonable estimation of body compartments such as total body water, fat mass and lean body mass. Periodic assessment of nutritional status must take into account the limitations of each criteria used.

Both low muscle mass and low fat are associated with higher all-cause mortality in hemodialysis patients

A higher body mass index is associated with better outcomes in hemodialysis patients; however, this index does not differentiate between fat and muscle mass. In order to clarify this, we examined the relationship between measures of fat and muscle mass and mortality in 1709 patients from the Hemodialysis Study. Triceps skin-fold thickness was used to assess body fat and mid-arm muscle circumference was used to assess muscle mass. Cox regression was used to evaluate the relationship between measures of body composition with all-cause mortality after adjustments for demographic, cardiovascular, dialysis, and nutrition-related risk factors. During a median follow-up of 2.5 years, there were 802 deaths. In adjusted models with continuous covariates, higher triceps skin-fold thickness and higher body mass index were significantly associated with decreased hazards of mortality, while higher mid-arm muscle circumference showed a trend toward decreased mortality. In adjusted models, lower quartiles of triceps skin-fold thickness, mid-arm muscle circumference, and body mass index were all significantly associated with higher all-cause mortality. These studies show that body composition in end-stage renal disease bears a complex relationship to all-cause mortality.

Diagnóstico nutricional de pacientes em hemodiálise na cidade de São Luís (MA)

OBJETIVO: Avaliar o estado nutricional de pacientes em hemodiálise na cidade de São Luís (MA). MÉTODOS: Foram avaliados 399 pacientes dos três centros de diálise da cidade, que preencheram os seguintes critérios de inclusão: possuir idade maior ou igual a 18 anos, encontrar-se em tratamento hemodialítico três vezes na semana há no mínimo três meses, não ser portador de doenças consumptivas. Para avaliação do estado nutricional foram utilizados índice de massa corporal, circunferência muscular do braço, prega cutânea tricipital, percentual de gordura corporal, níveis séricos de albumina, creatinina, colesterol total e avaliação subjetiva global. RESULTADOS: Os pacientes (idade de 49,6 anos, DP=15,6, sendo 248 homens) apresentaram eutrofia, quando avaliados por meio do índice de massa corporal (62,5%) e pelo percentual de gordura corporal (54,9%), e desnutrição, segundo a circunferência muscular do braço (63,0%) e a prega cutânea tricipital (63,0%). A medida da circunferência muscular do braço evidenciou maior proporção de desnutrição nos homens (75,9%), enquanto que a da prega cutânea tricipital nas mulheres (72,7%). O nível sérico de albumina ficou abaixo de 4,0g/dL em 67% dos pacientes estudados. A população como um todo apresentou níveis séricos de creatinina dentro do esperado e de colesterol total na faixa mínima de normalidade. A avaliação subjetiva global demonstrou desnutrição em 61,0% dos pacientes. CONCLUSÃO: A maior parte da população estudada foi classificada como desnutrida, considerando os critérios de circunferência muscular do braço, prega cutânea tricipital, avaliação subjetiva global e albumina, e em risco nutricional, considerando os critérios bioquímicos creatinina e colesterol total. Estes dados indicam a necessidade de medidas para melhoria do estado nutricional desta população.

Body composition analysis with bioelectric impedance in adult Indians with ESRD: Comparison with healthy population

Evaluation of body composition provides clinically useful information in several diseases including chronic kidney disease. Bioimpedance analysis (BIA) is a simple, cheap, and noninvasive tool for monitoring body composition. We performed BIA in 451 healthy adults and 162 end-stage renal disease (ESRD) patients. Resistance (R) and reactance (Xc) values were obtained at 50-kHz frequency using a tetrapolar impedance meter. Body compartments were derived using population-specific regression equations. Phase angles (arctan Xc/R) were calculated and impedance vector distribution was determined using the RXc graph method. Compared to healthy population, ESRD patients had similar post-dialysis resistance with lower reactance and phase angle, indicating decreased soft tissue mass and inadequate ultrafiltration. BIA equations estimated decreased fat mass index and intracellular water, whereas the total body and extracellular water percentages were increased. Sex-specific reference RXc plots with 95, 75, and 50% tolerance ellipses were drawn for the healthy population. A significant difference was noted in the vector positions and 95% confidence ellipses of the two sexes and body mass indices of </=25 and >25. In conclusion, we present the reference BIA parameters for Indian population. ESRD patients show significant body compartment alterations. The RXc score graph can differentiate ESRD patient from normal controls and can be used to monitor nutrition and hydration status.

Influência do hiperparatireoidismo secundário grave no estado nutricional de pacientes com insuficiência renal crônica

OBJETIVO: Avaliar o efeito do paratormônio na ingestão alimentar e sua relação com a composição corporal de pacientes em programa de hemodiálise com hiperparatireoidismo secundário. MÉTODOS: Foram avaliados 26 pacientes adultos, com média de idade de 47 ± 8 anos, divididos em dois grupos, de acordo com os níveis de paratormônio, e pareados por sexo. No grupo 1 (n=3) os níveis de paratormônio eram maiores que 300pg/ml (1.486±920pg/ml), e no grupo 2 (n=13), menores que 300pg/ml (199,8±122,2pg/ml). Todos os pacientes realizaram registro alimentar de três dias, medidas antropométricas e exames bioquímicos séricos para avaliar o metabolismo ósseo. RESULTADOS: Os pacientes do grupo 1 apresentaram índice de massa corporal, porcentagem da circunferência muscular do braço, da prega cutânea triciptal e de gordura corpórea, significativamente menores que os pacientes do grupo 2 (p<0,05). Houve correlação negativa e significante entre o paratormônio e a gordura corporal (r=-0,6; p<0,05). Em adição, a análise de regressão linear múltipla mostrou que o paratormônio, junto com o tempo em diálise, explicam em 42% a diminuição da gordura corporal total. Quanto à ingestão de nutrientes e aos marcadores bioquímicos, com exceção do paratormônio, não houve diferença estatisticamente significante entre os dois grupos. As ingestões de energia, proteína e cálcio estavam abaixo das recomendações para pacientes em diálise, e a ingestão de fósforo foi em média 11 ± 6mg/kg/dia e 15 ± 5mg/kg/dia, e considerada adequada para esta população. CONCLUSÃO: Com ingestão alimentar semelhante, quanto maior o nível de paratormônio e o tempo em diálise, menor é a gordura corporal nos pacientes com hiperparatireoidismo secundário grave, o que mostra que níveis altos de paratormônio contribuem para alterações no estado nutricional nestes pacientes.

Effect of folic acid on methionine and homocysteine metabolism in end-stage renal disease

BACKGROUND

The pathogenesis of hyperhomocysteinemia in end-stage renal disease (ESRD) is unclear. Folic acid lowers, but does not normalize, the plasma homocysteine level in patients with ESRD, but its effect on whole body metabolism of homocysteine is unknown.

METHODS

We studied the effect of 3 weeks of oral treatment with 5 mg folic acid per day on homocysteine metabolism in six chronic hemodialysis patients and six healthy controls. Primed, continuous infusions with [(2)H(3)-methyl-1-(13)C] methionine were used to determine flux rates of methionine transmethylation, homocysteine remethylation, and homocysteine transsulfuration. Metabolic homocysteine clearance was defined as the ratio of transsulfuration and plasma homocysteine level.

RESULTS

Folic acid treatment lowered plasma homocysteine significantly by 39% (95% CI 5 to 73) in the ESRD group, but plasma homocysteine remained higher than baseline values in the control group. In ESRD patients, homocysteine remethylation and methionine transmethylation rate increased by 34% (95% CI 5 to 62) and 22% (95% CI 5 to 39), respectively (i.e., levels that were similar to the baseline values of the control group). Transsulfuration rate and metabolic homocysteine clearance were not significantly altered by folic acid treatment in both the ESRD and the control group.

CONCLUSION

In ESRD patients, folic acid treatment lowers, but does not normalize plasma homocysteine, whereas homocysteine remethylation and methionine transmethylation increase to levels found in untreated healthy controls. These findings indicate a persistent, folate-independent, defect in metabolic homocysteine clearance in ESRD.

Homocysteine clearance and methylation flux rates in health and end-stage renal disease: association withS-adenosylhomocysteine

Hyperhomocysteinemia is a risk factor for cardiovascular disease and occurs frequently in end-stage renal disease (ESRD), but its pathogenesis is poorly understood. We aimed to evaluate one-carbon flux rates of methionine and homocysteine (Hcy) in ESRD patients and healthy controls. Transmethylation (TM), remethylation (RM), and transsulfuration (TS), as well as Hcy clearance by TS (i.e., TS/plasma total Hcy concentration) and by RM (i.e., RM/plasma total Hcy concentration) were evaluated in relation to body composition, vitamins, and S-adenosylhomocysteine (AdoHcy) and S-adenosylmethionine (AdoMet) levels. After a fixed protein diet for 3 days, primed-continuous infusion of [2H3-methyl-1-13C]methionine was performed in the postabsorptive state in 12 hemodialysis patients and 16 healthy volunteers. Hcy clearance by TS (−80%, P < 0.001) and by RM (−77%, P < 0.001) in ESRD patients was decreased compared with healthy controls. The absolute flux rates of TM (−27%, P < 0.01) and RM (−28%, P = 0.02) were lower in the ESRD patients. After adjustment for age, TS was not significantly reduced. Whole blood AdoHcy was significantly elevated in ESRD and was a significant determinant of TM (standardized β = −1.24, P = 0.01) and RM (standardized β = −1.43, P = 0.03). In conclusion, patients with ESRD have impaired Hcy clearance by TS and RM. Elevated whole blood AdoHcy levels are associated with impaired RM and TM flux rates in these patients, and AdoHcy may be a key regulatory compound in one-carbon flux.

Assessment of body composition by dual energy X-ray absorptiometry, skinfold thickness and creatinine kinetics in chronic kidney disease patients

BACKGROUND

Finding a method that can be routinely used to assess body composition with minimum error is still a challenge for those who work with chronic kidney disease (CKD) patients. This study aimed to compare the value of two surrogate techniques, skinfold thickness (SKF) and creatinine kinetics (CK) with dual energy X-ray absorptiometry (DEXA) as the reference method for measuring body fat and fat-free mass in non-dialysed CKD patients.

METHODS

The body fat and fat-free mass of 50 non-dialysed CKD patients (38 male, 12 female) were measured by DEXA and compared with measurements obtained by SKF and CK.

RESULTS

The mean values of body fat and fat-free mass obtained by SKF and CK differed significantly from measurements made by DEXA. The intra-class correlation coefficient (r) for body fat between SKF and DEXA (r = 0.74) and between CK and DEXA (r = 0.47) indicated a moderate degree of reproducibility. A Bland and Altman plot analysis showed a better agreement between SKF and DEXA [5.8 +/- 3.9% (-2.0 to 13.6)] than between CK and DEXA [8.8 +/- 8.8% (-8.8 to 26.4)]. Regarding fat-free mass, the intra-class correlation coefficient (r) between SKF and DEXA (r = 0.85) indicated a good degree of reproducibility, while that between SKF and CK (r = 0.57) indicated a moderate degree of reproducibility. The Bland and Altman plot analysis for fat-free mass showed that DEXA agreed better with SKF [-3.1 +/- 3.4 kg (-9.9 to 3.7)] than with CK [-5.5 +/- 6.4 kg (-18.2 to 7.3)].

CONCLUSION

Skinfold thickness seems to be the method of choice for evaluating body fat. The limitations inherent to DEXA in evaluating fat-free mass makes it difficult to designate an alternate method of choice for assessing this body compartment.

Métodos de avaliação da composição corporal em pacientes submetidos à hemodiálise

A avaliação da composição corporal de pacientes com insuficiência renal crônica em hemodiálise é de suma importância para propiciar uma conduta clínica e nutricional adequada, de forma a contribuir para a redução da elevada taxa de morbidade e mortalidade observada nesta população. No entanto, fatores relacionados à doença tais como anormalidades no estado de hidratação e presença de osteodistrofia renal, podem afetar a validade das técnicas de avaliação da composição corporal de pacientes com insuficiência renal crônica. Apesar dos inúmeros métodos de análise de composição corporal existentes, a maioria apresenta limitações para utilização na prática clínica da população em hemodiálise. Este artigo tem como objetivo revisar os métodos de composição corporal de fácil aplicabilidade na rotina clínica dos pacientes em hemodiálise tais como a somatória de pregas cutâneas, a bioimpedância elétrica e a interactância do infravermelho próximo.