Does dietary potassium intake associate with hyperkalemia in patients with chronic kidney disease?

BACKGROUND: Dietary potassium restriction is a strategy to control hyperkalemia in chronic kidney disease (CKD). However, hyperkalemia may result from a combination of clinical conditions. This study aimed to investigate whether dietary potassium or the intake of certain food groups associate with serum potassium in the face of other risk factors. METHODS: We performed a cross-sectional analysis including a nondialysis-dependent CKD (NDD-CKD) cohort and a hemodialysis (HD) cohort. Dietary potassium intake was assessed by 3-day food records. Underreporters with energy intake lower than resting energy expenditure were excluded. Hyperkalemia was defined as serum potassium >5.0 mEq/L. RESULTS: The NDD-CKD cohort included 95 patients {median age 67 [interquartile range (IQR) 55-73] years, 32% with diabetes mellitus (DM), median estimated glomerular filtration rate 23 [IQR 18-29] mL/min/1.73 m2} and the HD cohort included 117 patients [median age 39 (IQR 18-67) years, 50% with DM]. In NDD-CKD, patients with hyperkalemia (36.8%) exhibited lower serum bicarbonate and a tendency for higher serum creatinine, a higher proportion of DM and the use of renin-angiotensin-aldosterone system blockers, but lower use of sodium bicarbonate supplements. No association was found between serum and dietary potassium (r = 0.01; P = 0.98) or selected food groups. Conditions associated with hyperkalemia in multivariable analysis were DM {odds ratio [OR] 3.55 [95% confidence interval (CI) 1.07-11.72]} and metabolic acidosis [OR 4.35 (95% CI 1.37-13.78)]. In HD, patients with hyperkalemia (50.5%) exhibited higher serum creatinine and blood urea nitrogen and lower malnutrition inflammation score and a tendency for higher dialysis vintage and body mass index. No association was found between serum and potassium intake (r = -0.06, P = 0.46) or food groups. DM [OR 4.22 (95% CI 1.31-13.6)] and serum creatinine [OR 1.50 (95% CI 1.24-1.81)] were predictors of hyperkalemia in multivariable analyses. CONCLUSIONS: Dietary potassium was not associated with serum potassium or hyperkalemia in either NDD-CKD or HD patients. Before restricting dietary potassium, the patient's intake of potassium should be carefully evaluated and other potential clinical factors related to serum potassium balance should be considered in the management of hyperkalemia in CKD.

Nutritional status, hyperkalaemia and attainment of energy/protein intake targets in haemodialysis patients following plant-based diets: a longitudinal cohort study.

BACKGROUND: Patients undergoing haemodialysis (HD) are often discouraged from eating fruits and vegetables because of fears of hyperkalaemia and undernutrition, yet evidence to support these claims is scarce. We here explore the association between adherence to a healthy plant-based diet with serum potassium, surrogates of nutritional status and attainment of energy/protein intake targets in HD patients. METHODS: We performed an observational single-centre study of stable patients undergoing HD with repeated dietary assessment every 3 months. Patients were provided with personalized nutritional counselling according to current guidelines. The diet was evaluated by 3-day food records and characterized by a healthy plant-based diet score (HPDS), which scores positively the intake of plant foods and negatively animal foods and sugar. The malnutrition inflammation score (MIS) and serum potassium were also assessed at each visit. We used mixed-effects models to evaluate the association of the HPDS with markers of nutritional status, serum potassium levels and attainment of energy/protein intake targets. RESULTS: After applying inclusion and exclusion criteria, a total of 150 patients contributing to 470 trimestral observations were included. Their mean age was 42 years [standard deviation (SD) 18] and 59% were women. In multivariable models, a higher HPDS was not associated with serum potassium levels or odds of hyperkalaemia {potassium >5.5 mEq/L; odds ratio [OR] 1.00 [95% confidence interval (CI) 0.94-1.07] per HPDS unit higher}. Patients with a higher HPDS did not differ in terms of energy intake [OR for consuming <30 kcal/kg day 1.05 (95% CI 0.97-1.13)] but were at risk of low protein intake [OR for consuming <1.1 g of protein/kg/day 1.11 (95% CI 1.04-1.19)]. A higher HPDS was associated with a lower MIS, indicating better nutritional status. CONCLUSIONS: In patients undergoing HD, adherence to a healthy plant-based diet was not associated with serum potassium, hyperkalaemia or differences in energy intake. Although these patients were less likely to reach daily protein intake targets, they appeared to associate with better nutritional status over time.

Muscle Mass Assessed by Computed Tomography at the Third Lumbar Vertebra Predicts Patient Survival in Chronic Kidney Disease.

OBJECTIVE: Muscle mass is a key element for the evaluation of nutritional disturbances in patients with chronic kidney disease (CKD). Low muscle mass is associated with increased morbidity and mortality. The assessment of muscle mass by computed tomography at the third lumbar vertebra region (CTMM-L3) is an accurate method not subject to errors from fluctuation in the hydration status. Therefore, we aimed at investigating whether CTMM-L3 was able to predict mortality in nondialyzed CKD 3-5 patients. METHODS: This is a prospective observational cohort study. We evaluated 223 nondialyzed CKD patients (60.3 ± 10.6 years; 64% men; 50% diabetics; glomerular filtration rate 20.7 ± 9.6 mLmin1.73 m2). Muscle mass was measured by CTMM-L3 using the Slice-O-Matic software and analyzed according to percentile adjusted by gender. Nutritional parameters, laboratory data, and comorbidities were evaluated, and mortality was followed up for 4 years. RESULTS: During the study period, 63 patients died, and the main cause of death was cardiovascular disease. Patients who died were older, had lower hemoglobin and albumin, as well as lower muscle markers. CTMM-L3 below the 25th percentile was associated with higher mortality according to the Kaplan-Meier curve (P = .017) and in Cox regression analysis (crude hazard ratio, 1.87 [95% confidence interval, 1.11-3.16]), also when adjusting for potential confounders (hazard ratio 1.83 [95% confidence interval 1.02-3.30]). CONCLUSION: Low muscle mass measured by computed tomography at the third lumbar vertebra region is an independent predictor of increased mortality in nondialyzed CKD patients.

Design and methodology of the Aging Nephropathy Study (AGNES): a prospective cohort study of elderly patients with chronic kidney disease.

BACKGROUND: Renal replacement therapy (RRT) is usually indicated for patients with chronic kidney disease (CKD) with glomerular filtration rate below 10 ml/ml/min/1.73m2. However, the need for RRT and timing of dialysis initiation are debatable for patients aged 70 years or older. We here describe the study design and methodology of the Aging Nephropathy Study (AGNES) protocol that aims at evaluating to what extent geriatric-related conditions such as frailty, cognitive dysfunction, and presence of comorbidities have an impact on survival and RRT initiation in this group of patients. In this manuscript we provide detailed information about the AGNES study design and methodology. METHODS: AGNES is a prospective observational cohort that aim to investigate clinical, biochemical and demographic factors associated with RRT initiation and mortality of patients with CKD stage 4 or 5 who are aged 70 years and older. We plan to include 200 patients over 5 years. Clinically stable outpatients on conservative management for at least 6 months will be recruited from the Nephrogeriatric Clinic at the Hospital das Clinicas da Universidade de Sao Paulo, Brazil. Eligible patients are submitted to a full clinical examination, geriatric assessment, and blood test at baseline. Following the baseline visit the patients are being monitored during an observational follow up period of at least 12 months during which patients will be contacted in the clinic at their regular follow up or by phone until either RRT initiation or death occurs. This cohort includes evaluation of cognition by the education-adjusted 10-point Cognitive Screener (10-CS), frailty by Fried index score, a complete nutritional assessment (by body composition assessment, global subjective assessment and dietary intake), comorbidities by Charlson comorbidity index and biochemical markers including FGF-23 and Klotho. DISCUSSION: The AGNES cohort, a real-world study of current clinical practice in elderly patients with advanced CKD prior to dialysis initiation, will shed light into progression of CKD and its complications, indications of RRT and factors determining survival. This investigation will elucidate to what extent geriatric conditions, nutritional status and clinical factors are associated with survival, quality of life and RRT initiation in elderly CKD patients not yet on dialysis. TRIAL REGISTRATION: Registered on ClinicalTrials.gov on 18 October 2019 ( NCT04132492 ).

Global Prevalence of Protein-Energy Wasting in Kidney Disease: A Meta-analysis of Contemporary Observational Studies From the International Society of Renal Nutrition and Metabolism.

OBJECTIVE: To better define the prevalence of protein-energy wasting (PEW) in kidney disease is poorly defined. METHODS: We performed a meta-analysis of PEW prevalence from contemporary studies including more than 50 subjects with kidney disease, published during 2000-2014 and reporting on PEW prevalence by subjective global assessment or malnutrition-inflammation score. Data were reviewed throughout different strata: (1) acute kidney injury (AKI), (2) pediatric chronic kidney disease (CKD), (3) nondialyzed CKD 3-5, (4) maintenance dialysis, and (5) subjects undergoing kidney transplantation (Tx). Sample size, period of publication, reporting quality, methods, dialysis technique, country, geographical region, and gross national income were a priori considered factors influencing between-study variability. RESULTS: Two studies including 189 AKI patients reported a PEW prevalence of 60% and 82%. Five studies including 1776 patients with CKD stages 3-5 reported PEW prevalence ranging from 11% to 54%. Finally, 90 studies from 34 countries including 16,434 patients on maintenance dialysis were identified. The 25th-75th percentiles range in PEW prevalence among dialysis studies was 28-54%. Large variation in PEW prevalence across studies remained even when accounting for moderators. Mixed-effects meta-regression identified geographical region as the only significant moderator explaining 23% of the observed data heterogeneity. Finally, two studies including 1067 Tx patients reported a PEW prevalence of 28% and 52%, and no studies recruiting pediatric CKD patients were identified. CONCLUSION: By providing evidence-based ranges of PEW prevalence, we conclude that PEW is a common phenomenon across the spectrum of AKI and CKD. This, together with the well-documented impact of PEW on patient outcomes, justifies the need for increased medical attention.

Screening for muscle wasting and dysfunction in patients with chronic kidney disease.

Skeletal muscle mass and muscle function are negatively affected by a variety of conditions inherent to chronic kidney disease (CKD) and to dialysis treatment. Skeletal muscle mass and function serve as indicators of the nutritional and clinical state of CKD patients, and low values or derangements over time are strong predictors of poor patient outcomes. However, muscle size and function can be affected by different factors, may decline at different rates, and may have different patient implications. Therefore, operational definitions of frailty and sarcopenia have emerged to encompass these 2 dimensions of muscle health, i.e., size and functionality. The aim of this review is to appraise available methods for assessment of muscle mass and functionality, with an emphasis on their accuracy in the setting of CKD patients. We then discuss the selection of reference cutoffs for defining conditions of muscle wasting and dysfunction. Finally, we review definitions applied in studies addressing sarcopenia and frailty in CKD patients and discuss their applicability for diagnosis and monitoring.

Sarcopenia in chronic kidney disease on conservative therapy: prevalence and association with mortality.

BACKGROUND: In chronic kidney disease (CKD), multiple metabolic and nutritional abnormalities contribute to the impairment of skeletal muscle mass and function thus predisposing patients to the condition of sarcopenia. Herein, we investigated the prevalence and mortality predictive power of sarcopenia, defined by three different methods, in non-dialysis-dependent (NDD) CKD patients. METHODS: We evaluated 287 NDD-CKD patients in stages 3-5 [59.9 ± 10.5 years; 62% men; 49% diabetics; glomerular filtration rate (GFR) 25.0 ± 15.8 mL/min/1.73 m(2)]. Sarcopenia was defined as reduced muscle function assessed by handgrip strength (HGS <30th percentile of a population-based reference adjusted for sex and age) plus diminished muscle mass assessed by three different methods: (i) midarm muscle circumference (MAMC) <90% of reference value (A), (ii) muscle wasting by subjective global assessment (B) and (iii) reduced skeletal muscle mass index (<10.76 kg/m² men; <6.76 kg/m² women) estimated by bioelectrical impedance analysis (BIA) (C). Patients were followed for up to 40 months for all-cause mortality, and there was no loss of follow-up. RESULTS: The prevalence of sarcopenia was 9.8% (A), 9.4% (B) and 5.9% (C). The kappa agreement between the methods were 0.69 (A versus B), 0.49 (A versus C) and 0.46 (B versus C). During follow-up, 51 patients (18%) died, and the frequency of sarcopenia was significantly higher among non-survivors. In crude Cox analysis, sarcopenia diagnosed by the three methods was associated with a higher hazard for mortality; however, only sarcopenia diagnosed by method C remained as a predictor of mortality after multivariate adjustment. CONCLUSIONS: The prevalence of sarcopenia in CKD patients on conservative therapy varies according to the method applied. Sarcopenia defined as reduced handgrip strength and low skeletal muscle mass index estimated by BIA was an independent predictor of mortality in these patients.

The role of osteopontin and osteocyte-derived factors in secondary hyperparathyroidism-induced myopathy.

Muscle weakness is a common symptom in CKD patients, and the pathway by which secondary hyperparathyroidism (SHPT) affects muscle function is unknown. Osteopontin (OPN), a bone matrix protein stimulated by PTH and phosphate, has been associated with inflammatory muscle diseases. In this observational and prospective cohort study, we evaluated 30 patients with severe SHPT (39 ± 12 yr; 18 women), before and 6 mo after parathyroidectomy (PTx). We examined the relationships among CKD-mineral and bone disorder parameters; myokine and inflammatory cytokine levels; and changes in resting energy expenditure (REE), muscle function, BMD, and muscle-related proteins. At baseline, the patients showed low gene expression of muscle turnover markers and irisin, as well as high protein expression of OPN, transforming growth factor beta (TGF-ß), and fibroblast growth factor 21. Six months after PTx, REE and muscle mass had not changed, but physical performance, muscle strength, and bone mass improved, more so in patients undergoing total PTx. Also, there were reductions in the protein expression of OPN (11 vs 3%, p=.01) and TGF-ß (21 vs 7%, p=.002) in muscle, together with a significant increase in irisin muscular levels (30 vs 35 pg/mg, p=.02). The gain in bone mass and the increase in irisin levels correlated with a reduction in PTH. The levels of interleukin (IL)-1ß, tumor necrosis factor alpha, and IL-17 (markers of myositis) were also lower after PTx. Our data suggest that SHPT plays a role in CKD-induced muscle dysfunction, indirectly, via release of bone-specific proteins, which is partially reverted with PTx.

Are prediction equations reliable for estimating resting energy expenditure in chronic kidney disease patients?

BACKGROUND: The determination of resting energy expenditure (REE) is the primary step for estimating the energy requirement of an individual. Although numerous equations have been formulated for predicting metabolic rates, there is a lack of studies addressing the reliability of those equations in chronic kidney disease (CKD). Thus, the aim of this study was to evaluate whether the main equations developed for estimating REE can be reliably applied for CKD patients. METHODS: A total of 281 CKD patients (124 non-dialysis, 99 haemodialysis and 58 peritoneal dialysis) and 81 healthy control individuals were recruited. Indirect calorimetry and blood sample collection were performed after a 12-h fasting. Two most traditionally used equations for estimating REE were chosen for comparison with the REE measured by indirect calorimetry: (i) the equation proposed by Harris and Benedict, and (ii) the equation proposed by Schofield that is currently recommended by the FAO/WHO/UNU. RESULTS: Schofield's equation exhibited higher REE [1492±220 kcal/day (mean±SD)] in relation to Harris and Benedict's equation (1431±214 kcal/day; P<0.001), and both prediction equations showed higher REE in comparison with the reference indirect calorimetry (1352±252 kcal/day; P<0.001). In patients with diabetes, inflammation or severe hyperparathyroidism, the REE estimated by the Harris and Benedict equation was equivalent to that measured by indirect calorimetry. The intraclass correlation of the REE measured by indirect calorimetry with the Schofield's equation was r=0.48 (P<0.001) and with the Harris and Benedict's equation was r=0.58 (P<0.001). According to the Bland and Altman analysis, there was a large limit of agreement between both prediction equations and the reference method. Acceptable prediction of REE (90-110% adequacy) was found in 47% of the patients by using the Harris and Benedict's equation and in only 37% by using the Schofield's equation. CONCLUSIONS: The most traditionally used prediction equations overestimated the REE of CKD patients, and the errors were minimized in the presence of comorbidities. There is a need to develop population-specific equations in order to adequately estimate the energy requirement of these patients.

Biomimetics provides lessons from nature for contemporary ways to improve human health.

Homo sapiens is currently living in serious disharmony with the rest of the natural world. For our species to survive, and for our well-being, we must gather knowledge from multiple perspectives and actively engage in studies of planetary health. The enormous diversity of species, one of the most striking aspects of life on our planet, provides a source of solutions that have been developed through evolution by natural selection by animals living in extreme environments. The food system is central to finding solutions; our current global eating patterns have a negative impact on human health, driven climate change and loss of biodiversity. We propose that the use of solutions derived from nature, an approach termed biomimetics, could mitigate the effects of a changing climate on planetary health as well as human health. For example, activation of the transcription factor Nrf2 may play a role in protecting animals living in extreme environments, or animals exposed to heat stress, pollution and pesticides. In order to meet these challenges, we call for the creation of novel interdisciplinary planetary health research teams.

Plant-based diets, insulin sensitivity and inflammation in elderly men with chronic kidney disease.

BACKGROUND: In persons with CKD, adherence to plant-based diets is associated with lower risk of CKD progression and death, but underlying mechanisms are poorly characterized. We here explore associations between adherence to plant-based diets and measures of insulin sensitivity and inflammation in men with CKD stages 3-5. METHODS: Cross-sectional study including 418 men free from diabetes, aged 70-71 years and with cystatin-C estimated glomerular filtration rate (eGFR) <60 mL/min/1.73m2 and not receiving kidney-specific dietetic advice. Information from 7-day food records was used to evaluate the adherence to a plant-based diet index (PBDi), which scores positively the intake of plant-foods and negatively animal-foods. Insulin sensitivity and glucose disposal rate were assessed with the gold-standard hyperinsulinemic euglycemic glucose clamp technique. Inflammation was evaluated by serum concentrations of C-reactive protein (CRP) and interleukin (IL)-6. Associations were explored through linear regression and restricted cubic splines. RESULTS: The majority of men had CKD stage 3a. Hypertension and cardiovascular disease were the most common comorbidities. The median PBDi was 38 (range 14-55). Across higher quintiles of PBDi (i.e. higher adherence), participants were less often smokers, consumed less alcohol, had lower BMI and higher eGFR (P for trend <0.05 for all). Across higher PBDi quintiles, patients exhibited higher insulin sensitivity and lower inflammation (P for trend <0.05). After adjustment for eGFR, lifestyle factors, BMI, comorbidities and energy intake, a higher PBDi score remained associated with higher glucose disposal rate and insulin sensitivity as well as with lower levels of IL-6 and CRP. CONCLUSION: In elderly men with non-dialysis CKD stages 3-5, adherence to a plant-based diet was associated with higher insulin sensitivity and lower inflammation, supporting a possible role of plant-based diets in the prevention of metabolic complications of CKD.

Plant-based diets to manage the risks and complications of chronic kidney disease.

Traditional dietary recommendations for patients with chronic kidney disease (CKD) focus on the quantity of nutrients consumed. Without appropriate dietary counselling, these restrictions can result in a low intake of fruits and vegetables and a lack of diversity in the diet. Plant nutrients and plant-based diets could have beneficial effects in patients with CKD: increased fibre intake shifts the gut microbiota towards reduced production of uraemic toxins; plant fats, particularly olive oil, have anti-atherogenic effects; plant anions might mitigate metabolic acidosis and slow CKD progression; and as plant phosphorus has a lower bioavailability than animal phosphorus, plant-based diets might enable better control of hyperphosphataemia. Current evidence suggests that promoting the adoption of plant-based diets has few risks but potential benefits for the primary prevention of CKD, as well as for delaying progression in patients with CKD G3-5. These diets might also help to manage and prevent some of the symptoms and metabolic complications of CKD. We suggest that restriction of plant foods as a strategy to prevent hyperkalaemia or undernutrition should be individualized to avoid depriving patients with CKD of these potential beneficial effects of plant-based diets. However, research is needed to address knowledge gaps, particularly regarding the relevance and extent of diet-induced hyperkalaemia in patients undergoing dialysis.

Waist circumference and visceral fat in CKD: a cross-sectional study.

BACKGROUND: In the general population, waist circumference was noted to be a reliable predictor of visceral fat. In addition, increased waist circumference was strongly associated with risk factors for cardiovascular disease. In patients with chronic kidney disease (CKD), the association of waist circumference with visceral fat was never tested. STUDY DESIGN: Cross-sectional study. SETTING & PARTICIPANTS: 122 patients with CKD not yet on dialysis therapy (75 men; diabetes mellitus, 30%; age, 55.3 +/- 11.3 years; body mass index, 27.1 +/- 5.2 kg/m(2); estimated glomerular filtration rate, 35.4 +/- 15.2 mL/min/1.73 m(2)) were studied. PREDICTOR: Waist circumference. OUTCOMES & MEASUREMENTS: Anthropometry, abdominal visceral fat measured by means of computed tomography, and cardiovascular disease risk factors. RESULTS: Waist circumference strongly correlated with visceral fat (r = 0.75 for men, r = 0.81 for women; P < 0.01). kappa Statistic was 0.56, indicating relatively good agreement between methods. Body mass index showed a lower correlation coefficient (r = 0.68 for men, r = 0.76 for women; P < 0.01) and poor agreement (0.36) with visceral fat in comparison to waist circumference. In men, waist circumference and visceral fat similarly correlated with high-density lipoprotein cholesterol level, triacylglycerol level, and Homeostasis Model Assessment Index (P < 0.05). In women, waist circumference correlated with age, C-reactive protein level, and Homeostasis Model Assessment Index, whereas visceral fat also correlated with low-density lipoprotein cholesterol and triacylglycerol levels (P < 0.05). LIMITATIONS: Findings are restricted to patients with CKD not yet on dialysis therapy from a single center. CONCLUSIONS: Waist circumference was strongly associated with visceral fat in patients with CKD. Associations between waist circumference and cardiovascular disease risk factors were similar to those observed for visceral fat, particularly in men. These findings suggest that waist circumference may be a simple and inexpensive tool to be used in epidemiological studies.

Inflammation is associated with increased energy expenditure in patients with chronic kidney disease.

BACKGROUND: Inflammation, a clinical condition observed in patients with chronic kidney disease (CKD), may be related to increased resting energy expenditure (REE). OBJECTIVES: The main objective was to investigate the relation between inflammation and REE in patients with CKD who are not undergoing dialysis. We also aimed to analyze whether a decrease in C-reactive protein (CRP) would result in a reduction in REE. DESIGN: This study enrolled 132 patients with CKD who were not undergoing dialysis, who had creatinine clearance from 5 to 65 mL.min(-1).1.73 m(-2), and who were 53.6 +/- 16 y old; 82 (62.1%) were men. Twenty-nine patients had clinical signs of infection. REE was measured by using indirect calorimetry, and inflammation was evaluated by using high-sensitivity CRP measurement. Patients were divided according to tertiles of CRP with the following intertertile ranges: first tertile, CRP < or = 0.14 mg/dL (n = 43); second tertile, CRP 0.15-0.59 mg/dL (n = 46); and third tertile, CRP > or = 0.60 mg/dL (n = 43). REE was measured before and after treatment in 10 patients who had inflammation or infection. RESULTS: After adjustment for age, sex, and lean body mass, the REE of the third (1395 kcal/d; P = 0.02) and second (1355 kcal/d; P = 0.04) tertiles was significantly higher than that of the first tertile (1286 kcal/d). In the multiple linear regression analysis (n = 132), the independent determinants of REE were lean body mass, CRP, and age (R2 = 0.55). After treatment of infection in a subgroup of 10 patients, it was observed that a significant reduction in CRP concentration was accompanied by a significant reduction of 174 +/- 165 kcal that accounted for 13% of the initial REE. CONCLUSION: This study showed that inflammation is associated with increased REE in patients with CKD.

Serum and cellular interleukin-6 in haemodialysis patients: relationship with energy expenditure.

BACKGROUND: Inflammation is a highly prevalent condition among end-stage renal disease (ESRD) patients and it has been implicated with several metabolic derangements. Considering the harmful effect of hypermetabolism on nutritional status and clinical outcomes of ESRD patients, we aimed to investigate the relationship between proinflammatory cytokine interleukin-6 (IL-6) and energy expenditure in this population. METHODS: This cross-sectional study enrolled 80 adult haemodialysis patients for the evaluation of serum IL-6 and energy expenditure. The production of IL-6 by peripheral blood mononuclear cells (PBMCs) (spontaneous and endotoxin-stimulated production) was examined in a subgroup of 30 haemodialysis patients and in 11 healthy control subjects. IL-6 was measured by immunoenzymatic assay. The resting energy expenditure was evaluated by means of indirect calorimetry. Body composition was assessed by bioelectrical impedance analysis and skinfold thicknesses. RESULTS: Serum IL-6 [6.3 (2.2-163.5) pg/ml] correlated positively with age (R = 0.26; P = 0.02) and C-reactive protein (R = 0.31; P < 0.01). Resting energy expenditure correlated positively with lean body mass (R = 0.68; P < 0.001) and BMI (R = 0.44; P < 0.001), and negatively with Kt/V (R = -0.37; P < 0.01). In the multivariate analysis, controlling for age and lean body mass, serum IL-6 was positively associated with resting energy expenditure (n = 80; beta = 2.4; P = 0.01). The production of IL-6 by PBMCs did not reach statistically significant differences between patients and controls [spontaneous production 6541 (96-7739) pg/ml vs 3410 (50-7806) pg/ml, respectively; and stimulated production 6530 (579-7671) pg/ml vs 5304 (1527-7670) pg/ml, respectively]. IL-6 secreted by monocytes showed no association with either serum IL-6 or resting energy expenditure. CONCLUSION: Serum IL-6 was associated with an increase of energy expenditure in haemodialysis patients.

Resting energy expenditure in peritoneal dialysis patients.

OBJECTIVES: This study aimed to evaluate whether resting energy expenditure (REE) of patients undergoing peritoneal dialysis (PD) therapy differs from that of healthy individuals, as well as to investigate the factors associated with REE in this sample of patients. DESIGN: Cross-sectional study. SETTING: Dialysis Unit of the Nephrology Division, Federal University of Sao Paulo-Oswaldo Ramos Foundation, Brazil. SUBJECTS AND METHODS: The study examined the REE of 37 patients (20 males, age 44.5 +/- 13 years) undergoing PD therapy. Only patients older than 18 years, on PD for at least 3 months, without catabolic illness, and with normal thyroid function were included. Patients were pair matched for age and gender with 37 healthy individuals. REE was measured by indirect calorimetry. Body composition was assessed by dual-energy x-ray absorptiometry in the patients and by bioelectrical impedance in the healthy individuals. RESULTS: The REE of PD patients was similar to that of pair-matched controls (1372 +/- 266 and 1453 +/- 252 kcal/day respectively, p = 0.13) even when adjusted for lean body mass and gender (p = 0.56). The REE of PD patients was positively correlated with lean body mass (r = 0.60, p < 0.01), fat mass (r = 0.43, p < 0.01), body mass index (r = 0.60, p < 0.01), serum glucose (r = 0.36, p < 0.05), and protein equivalent of nitrogen appearance (PNA; r = 0.42, p < 0.01). There were no correlations between REE and glucose absorption, dialysis-related parameters, C-reactive protein, and energy or protein intake by 3-day food diary. In the multiple linear regression analysis, using REE as the dependent variable, the final model showed that lean body mass and female gender were determinants of REE in PD patients (R(2) = 0.44). When separate analysis by gender was performed, REE correlated directly with body fat in female patients (r = 0.70, p < 0.01) but not in male patients (r = 0.29, p = 0.21). On the other hand, lean body mass was significantly correlated with REE in male patients (r = 0.78, p < 0.01) but not in female patients (r = 0.47, p = 0.06). CONCLUSIONS: This study showed that REE of PD patients did not differ from that of healthy individuals. The strong association between body fat and REE in female patients remains to be further investigated.