Journal of Renal Nutrition - Articles in Press

Weight Management Tips for Patients on Hemodialysis - Corrected Proof

Stacey Hickel — 2010-03-04

The prevalence of overweight and obesity in the renal population is increasing at an exponential rate proportionate to the prevalence seen in the general U.S. population. Dialysis units and transplant centers alike are faced with an estimated majority of patients (60%) awaiting transplantation who considered overweight or obese. Obesity as reflected by a body mass index (BMI) of 30kg/m2 or over is associated with increased morbidity from hypertension, dyslipidemia, type 2 diabetes, congestive heart disease, stroke, gallbladder disease, osteoarthritis, sleep apnea and respiratory problems, and certain types of cancer. Obesity is attributable to premature death and an increase in all-cause mortality.

Association of Relatively Low Serum Parathyroid Hormone With Malnutrition-Inflammation Complex and Survival in Maintenance Hemodialysis Patients - Corrected Proof

2010-03-04

Background: Low serum parathyroid hormone (PTH) has been implicated as a primary biochemical marker of adynamic bone disease in individuals with chronic kidney disease (CKD) who undergo maintenance hemodialysis (MHD) treatment. We hypothesized that the malnutrition-inflammation complex is associated with low PTH levels in these patients and confounds the PTH-survival association.Methods: We examined 748 stable MHD outpatients in southern California and followed them for up to 5 years (October 2001–December 2006).Results: In 748 MHD patients, serum PTH <150pg/mL was more prevalent among non-blacks and diabetics. There was no association between serum PTH and coronary artery calcification score, bone mineral density, or dietary protein or calorie intake. Low serum PTH was associated with markers of protein-energy wasting and inflammation, and this association confounded the relationship between serum PTH and alkaline phosphatase. Although 5-year crude mortality rates were similar across PTH increments, after adjustment for the case-mix and surrogates of malnutrition and inflammation, a moderately low serum PTH in 100–150pg/mL range was associated with the greatest survival compared to other serum PTH levels, i.e., a death hazard ratio of 0.52 (95% confidence interval: 0.29–0.92, p<0.001) compared to PTH of 300–600pg/mL (reference).Conclusions: Low serum PTH may be another facet of the malnutrition-inflammation complex in CKD, and after controlling for this confounder, a moderately low PTH in 100–150pg/mL range appears associated with the greatest survival. Limitations of observational studies should be considered.

Physical Exercise Prevents the Exacerbation of Oxidative Stress Parameters in Chronic Kidney Disease - Corrected Proof

2010-03-04

Objective: Reactive oxygen species play an important role in the pathogenesis of chronic kidney disease (CKD). Physical exercise was suggested as a useful approach to diminish impaired oxidative defense mechanisms. This study sought to observe the effects of physical training before the induction of renal lesions on oxidative stress parameters in animals induced for CKD.Methods: Twenty-four male Wistar rats were divided into four groups (n = 6): sham, sham plus exercise, CKD, and CKD plus exercise. Exercise groups performed physical training on a treadmill for 8 weeks (up to 1 km/h for 50 min/day, 5 days/week). Forty-eight hours after the final exercise session, a surgical reduction of renal mass was performed (5/6 nephrectomized). Thirty days later, blood samples were collected to determine serum creatinine and urea concentrations, and the right kidney was surgically removed and stored at −70°C for later analysis of superoxide production, antioxidant enzymes (superoxide dismutase and catalase), and oxidative damage of lipids (thiobarbituric acid reactive susbstances level) and proteins (carbonyl groups and sulfhydryl content).Results: A significant increase occurred in creatinine and urea levels, superoxide production, antioxidant enzymes, and oxidative damage in the CKD group, compared with sham-treated animals (P < .05). Physical training prevented superoxide production, and decreased the oxidative damage in the CKD group (P < .05), but did not increase the effect of antioxidants.Conclusion: Physical training before induction of a renal lesion is capable of improving oxidative damage parameters and oxidant production, without altering renal function and the antioxidant defense system.

L-Arginine and Antioxidant Diet Supplementation Partially Restores Nitric Oxide-Dependent Regulation of Phenylephrine Renal Vasoconstriction in Diabetics Rats - Corrected Proof

2010-01-25

Objective: The increase of reactive oxygen species (ROS) in diabetes potentiates the vascular effects of phenylephrine through nitric oxide (NO) impairment, facilitating the development of diabetic nephropathy. We propose that the combination of an antioxidant and L-arginine as diet supplements could prevent the increased vascular response to phenylephrine in diabetic animals.Design: Changes in the adrenergic system play an important role in the development of vascular complications in the prediabetic condition. The vasoconstrictor effects of phenylephrine are regulated by NO, and the impairment of endothelium-dependent vasodilation in diabetes is associated with ROS.Setting: Diabetes was induced with a low dose (55 mg/kg body weight) of streptozotocin in 7-week-old rats. Diabetic rats were fed with a diet supplement containing a combination of vitamin E, vitamin C, eicosapentaenoic acid, docosahexaenoic acid, and L-arginine, and the effects on phenylephrine-induced renal vascular responses were evaluated.Results: Phenylephrine increased the renal perfusion pressure of isolated perfused kidneys from diabetic rats compared with nondiabetic rats. This effect was associated with reduced nitrite release as well as reduced plasma tetrahydrobiopterin and increased superoxide anions in the renal tissue. Diet supplementation with a combination of L-arginine and vitamins in diabetic rats partially prevented the generation of superoxide associated with recovery of the renal release of NO and decreased phenylephrine-induced vasoconstrictor effects, compared with untreated diabetic rats. However, the administration of L-arginine or vitamins alone did not affect phenylephrine-induced vasoconstriction. Vitamin treatment alone did decrease superoxide generation.Conclusion: The protective mechanism of NO on the vasoconstrictor effects of phenylephrine in the kidney is lost during the development of diabetes, probably via the actions of ROS through a decrease in tetrahydrobiopterin, thus contributing to the pathogenesis of diabetic nephropathy. Restoration of this protective NO mechanism can be achieved by simultaneously stimulating NO synthesis and preventing the effects of ROS through the use of L-arginine and a combination of vitamins E and C as diet supplementation.

Adipokines and Nutritional Status for Patients on Maintenance Hemodialysis - Corrected Proof

2010-01-13

Objectives: The aim of this study was to investigate the serum concentration of adipokines, such as leptin, adiponectin, and resistin, and assess its relation to nutritional and inflammatory parameters in both overweight and normal weight patients on maintenance hemodialysis.Methods: A total of 36 hemodialysis patients (27 M, 9 F; mean age 55.3 ± 12 yr.) were examined and 23 additional healthy volunteers were recruited as the control group. The concentrations of leptin, leptin receptor, adiponectin, resistin, IL-6, TNFa and CRP were measured by ELISA. Assessment of nutritional status was determined by the levels of albumin, BMI, percentage of body fat (%F), lean body mass (LBM), and Subjective Global Assessment Score (SGA).Results: According to the SGA 7-points score and the albumin level, 20 patients were of good nutritional status (6-7 points), while 16 patients were mildly malnourished (4-5 points). The concentrations of CRP, resistin, adiponectin, and TNFa were statistically higher in hemodialysis patients than in the control group (p£0.05). The adiponectin level was inversely correlated with %F (R Spearman=-0.3; p £ 0.05). The level of leptin was positively correlated with %F as well as with BMI and SGA scores (R Spearman=0.4; p£0.05). Although there was no significant difference in the nutritional status between the nonoverweight (BMI 18.5-24.99) and overweight (BMI 325.0) groups of patients, in the nonoverweight group there were 12 patients (54.5%) with signs of mild malnutrition compared to 4 malnourished patients (28.5%) in the overweight group. Nonoverweight patients presented significantly lower leptin concentration (12.7 vs 27.8 ug/l) and higher adiponectin level (38.9 vs 32.5 ng/ml) when compared to overweight patients. The levels of IL-6 and TNFa were higher in the nonoverweight group of patients. Overweight patients also had shorter durations of stay in the hemodialysis program (30.5 vs. 87.6 months).Conclusion: The results of our study indicate that lean hemodialysis patients are more prone to malnutrition and inflammation. The increased levels of leptin and decreased levels of adiponectin in the overweight hemodialysis patients support the idea of a reverse epidemiology phenomenon in this group of patients.

Independent and Joint Associations of Nutritional Status Indicators With Mortality Risk Among Chronic Hemodialysis Patients in the Dialysis Outcomes and Practice Patterns Study (DOPPS) - Corrected Proof

2010-01-11

Objective: To consider the Kidney Disease Outcomes Quality Initiative recommendation of using multiple nutritional measurements for patients on maintenance dialysis, we explored data for independent and joint associations of nutritional indicators with mortality risk among maintenance hemodialysis patients treated in 12 countries.Setting: Dialysis units in seven European countries, the United States, Canada, Australia, New Zealand, and Japan.Main Outcome: Mortality risk.Methods: We conducted a prospective cohort study of 40,950 patients from phases I to III of the Dialysis Outcomes and Practice Patterns Study (1996–2008). Independent and joint effects (interactions) of nutritional indicators (serum creatinine, serum albumin, normalized protein catabolic rate, body mass index [BMI]) on mortality risk were assessed by Cox regression with adjustments for demographics, years on dialysis, and comorbidities.Results: Important variations in nutritional indicators were seen by country and patient characteristics. Poorer nutritional status assessed by each indicator was independently associated with higher mortality risk across regions. Significant multiplicative interactions (each p ≤ 0.01) between indicators were also observed. For example, by using patients with serum creatinine 7.5–10.5 mg/dL and BMI 21–25 kg/m2 as referent, BMI <21 kg/m2 was associated with lower mortality risk among patients with creatinine >10.5 mg/dL (relative risk = 0.68) but with higher mortality risk among those with creatinine <7.5 mg/dL (relative risk = 1.38). The association of lower albumin concentration with higher mortality risk was stronger for patients with lower BMI or lower creatinine.Conclusion: The joint effects of nutritional indicators on mortality indicate the need to use multiple measurements when assessing the nutritional status of hemodialysis patients.

Patient Perspectives on Fluid Management in Chronic Hemodialysis - Corrected Proof

2009-11-16

Objective: We sought to describe the perspectives and experiences of chronic hemodialysis (CHD) patients regarding self-care and adherence to fluid restrictions.Design: Semistructured focus groups.Setting: Two outpatient hemodialysis centers.Participants: Nineteen patients on chronic hemodialysis.Intervention: Patients were asked a series of open-ended questions to encourage discussion about the management of fluid restriction within the broad categories of general knowledge, knowledge sources or barriers, beliefs and attitudes, self-efficacy, emotion, and self-care skills.Main outcome measure: We analyzed session transcripts using the theoretical framework of content analysis to identify themes generated by the patients.Results: Patients discussed both facilitators and barriers to fluid restriction, which we categorized into six themes: knowledge, self-assessment, psychological factors, social, physical, and environmental. Psychological factors were the most common barriers to fluid restriction adherence, predominantly involving lack of motivation. Knowledge was the most discussed facilitator with accurate self-assessment, positive psychological factors, and supportive social contacts also playing a role. Dialysis providers were most commonly described as the source of dialysis information (54%), but learning through personal experience was also frequently noted (28%).Conclusion: Interventions to improve fluid restriction adherence of chronic hemodialysis patients should target motivational issues, assess and improve patient knowledge, augment social support, and facilitate accurate self-assessment of fluid status.

Are Ghrelin and Leptin Involved in Food Intake and Body Mass Index in Maintenance Hemodialysis? - Corrected Proof

2009-11-13

Objectives: Both leptin and ghrelin (in the forms of acyl ghrelin and des-acyl ghrelin) are involved in food intake, and appear to be dysregulated in chronic kidney disease. This study describes plasma leptin, acyl, and des-acyl ghrelin concentrations in relation to protein intake and body mass index (BMI) in hemodialysis (HD) patients.Design: This was a cross-sectional study.Setting: This study was conducted during the baseline phase of the French multicenter Influence of a High-Flux Dialyzer on Long-Term Leptin Levels Study.Patients: We studied 125 HD patients (aged 72.5±11.7 years; 59% males).Main Outcome Measure: Blood samples were collected during fasting, and before a regular HD session. Plasma ghrelin and leptin were evaluated. The protein equivalents of total nitrogen appearance and BMI were calculated.Results: Patients demonstrated elevated serum leptin (48.0±49.0 ng/mL) and des-acyl ghrelin (646.6±489.5 pg/mL) levels, and low acyl ghrelin levels (29.8±58.5 pg/mL), according to normal values. Acyl ghrelin was negatively correlated with C-reactive protein (r=−0.34, P < .001). The des-acyl to acyl ghrelin ratio was negatively correlated with protein intake, as estimated by normalized Protein Nitrogen Appearance (r=−0.22, P=.01). Serum leptin exhibited its well-described positive correlation with BMI and waist circumference, but the other hormones did not.Conclusions: This study reports high des-acyl ghrelin and leptin levels and low acyl ghrelin levels in HD patients, a finding potentially associated with inflammation and food intake.

Glutathione and Riboflavin Status in Supplemented Patients Undergoing Home Nocturnal Hemodialysis versus Standard Hemodialysis - Corrected Proof

2009-11-13

Background: Patients on conventional hemodialysis (HD) have elevated markers of oxidative stress and chronic inflammation, which may contribute to a high prevalence of cardiovascular disease. Glutathione (GSH), an important intracellular antioxidant, requires cysteine as a rate-limiting amino acid for its synthesis and riboflavin for its regeneration.Objectives: We aimed to examine whether erythrocyte GSH (eGSH) concentrations and riboflavin status are influenced by the increased dialysis dose provided to vitamin-supplemented patients receiving home nocturnal hemodialysis (HNHD) (6–8 hours/session, 5–7 nights/week) compared with patients on standard hemodialysis (SHD) (4 hours/session, 3 days/week).Method: This was a cross-sectional comparative study involving 30 patients undergoing SHD or HNHD regimens and a group of 15 healthy control subjects (HC). We measured eGSH concentration by liquid chromatography–tandem mass spectrometry, riboflavin status by eGSH reductase activity coefficient (EGRAC) as well as plasma total cysteine (Cys) and total homocysteine (Hcy), vitamin C by high-performance liquid chromatography, and C-reactive protein (CRP) by standard method. Estimated dietary protein and energy intakes were determined by 3-day food records, and nutritional status was assessed by subjective global assessment (SGA).Results: There were no significant differences among groups in eGSH concentration, EGRAC, dietary protein intake, and SGA score. SHD patients had significantly higher plasma Cys (P < .001) and Hcy compared with HNHD and HC groups (P = .048). Vitamin C was significantly lower (P = .01) and CRP significantly higher (P = .048) in both HD groups compared with HC.Conclusion: eGSH concentration appears to be unaffected by dialysis dose in well-nourished HD patients.

Underreporting of Energy Intake in Peritoneal Dialysis Patients - Corrected Proof

2009-10-23

Objectives: This study aimed to assess the prevalence of underreporting among patients treated by peritoneal dialysis (PD), and to investigate whether the reported energy intake is influenced by overweight status in this population.Design: This was a prospective, observational study.Setting: This study took place at the Dialysis Unit of the Nephrology Division, Federal University of São Paulo-Oswaldo Ramos Foundation, São Paulo, Brazil.Patients: Forty adult patients were recruited: 24 men and 16 women; age, 53.4±16.5 years; body mass index (BMI), 25.1±3.8 kg/m2 (x±SD); median duration of dialysis, 19 months (range, 3 to 101 months). Only patients on PD >3 months, free of peritonitis for at least 3 months, without catabolic conditions and with normal thyroid function, were included.Methods: Energy intake was evaluated using a 3-day food record. Resting energy expenditure (REE) was measured by indirect calorimetry. Body composition was assessed using dual-energy x-ray absorptiometry. The total energy (TE) offered was considered the sum of energy intake plus energy provided by glucose absorption. All measurements were collected at baseline and after 6 months. Underreporting of energy intake was considered to have occurred when the TE/REE ratio was <1.40.Results: The TE/REE ratio was 1.35±0.31. Twenty-one patients (52.5%) had a TE/REE ratio <1.40. The TE/REE ratio correlated negatively with BMI (r=−0.52, P < .01), and positively with duration of dialysis (r=0.44, P < .01). No correlation was found between TE/REE ratio and any other variables. Patients were divided into two groups according to BMI <25 kg/m2 and BMI ≥25 kg/m2. The majority of patients (83.3%) in the higher BMI group had a TE/REE ratio <1.40. In a logistic regression analysis, using TE/REE ratio <1.40 or ≥1.40 as the dependent variable, BMI≥25 kg/m2 was the only determinant of energy underreporting. After 6 months of follow-up, no change in either body weight or BMI was evident.Conclusions: This study showed that a significant number of PD patients underreported the energy intake evaluated by 3-day food diaries. This finding was evidenced particularly in overweight patients.

Nutrition-Related Cardiovascular Risk Factors in Hemodialysis Patients - Corrected Proof

Yasemin Arslan, Gul Kiziltan — 2009-10-12

Objective: This study sought to determine nutrition-related cardiovascular risk factors in hemodialysis patients.Design: This was a cross-sectional study.Setting: This study included outpatients from the Hemodialysis Unit of Baskent University Ankara Hospital.Patients: This study was conducted on 93 endstage chronic renal-failure patients (50 male and 43 female) aged between 18 and 65 years. Patients undergoing hemodialysis three times weekly with 4 hours of standardized bicarbonate hemodialysis were included. Patients with cardiovascular disease were excluded.Main Outcome Measure: A questionnaire was administered to patients regarding demographic and disease information. The nutritional status of patients was determined by a food-frequency questionnaire, a 3-day, 24-hour dietary record, and subjective global assessment. Several biochemical parameters were analyzed, and body weight was measured.Results: Percentages of patients' serum total cholesterol, low-density lipoprotein cholesterol, triglyceride, and total cholesterol/low-density lipoprotein cholesterol levels that were higher than National Kidney Foundation (NKF) and National Cholesterol Education Program Adult Treatment Panel III (NCEP/ATP III) criteria amounted to 7.5%, 4.3%, 43%, and 10.8%, respectively. The percentage of patients' serum high-density lipoprotein cholesterol levels that were lower than NKF and NCEP/ATP III criteria reached 41.9%. According to serum albumin levels, 44.1% of patients were malnourished. In terms of patients' dietary total fat intake, 98.9% were higher than NKF and NCEP/ATP III criteria, and all patients' dietary saturated fatty acids intake were higher than recommended. For 87.1% of patients, the dietary polyunsaturated fatty acids/saturated fatty acids ratio was <1. Moreover, in terms of NKF recommendations, the percentages of patients with insufficient dietary folate and vitamin B12 intake reached 100% and 61.3%, respectively.Conclusion: Hemodialysis patients should be considered at high risk for developing cardiovascular disease. Therefore, when planning diets of endstage renal disease patients, it is important to consider nutrition-related cardiovascular-disease risk factors for the sake of quality of life and survival.

Adherence to the Mediterranean Diet is Associated With Renal Function Among Healthy Adults: The ATTICA Study - Corrected Proof

2009-10-12

Background: No data exist regarding the effect of the Mediterranean diet on renal function. We studied the association between adherence to the Mediterranean diet and markers of renal function among 3042 people without any evidence of chronic disease.Methods: During 2001 and 2002, a random sample was selected of 1514 men and 1528 women (aged 18 to 89 years) from Greece. Urea and creatinine were measured, and the creatinine-clearance (CCr) rate was estimated according to the formula of Cockcroft and Gault. Adherence to the Mediterranean diet was assessed using a validated diet score (MedDietScore) that incorporated the inherent characteristics of this diet.Results: The CCr rate was positively associated with MedDietScore (b±SE, 0.24±0.09, P=.007). Moreover, urea and creatinine levels were inversely associated with MedDietScore (b±SE, −0.05±0.02, P=.01, and −0.004±0.001, P < .001, respectively). Multiple linear regression analysis revealed that for each 10/55 additional points in diet score, a 3.7-unit increase in CCr rate in women (P < .001) and a 10.1-unit increase in CCr rate in men were evident (P < .001). Further analysis revealed that the CCr rate was positively correlated with the consumption of fruits (ρ =0.08, P=.009) and moderate alcohol consumption, and inversely correlated with the consumption of potatoes (ρ=−0.11, P < .001), red meat (ρ=−0.12, P=.001), and poultry (ρ=−0.07, P=.02).Conclusions: Greater adherence to the Mediterranean diet was independently associated with reduced urea and creatinine and increased CCr rates among healthy men and women. This finding adds to the knowledge regarding the benefits of a traditional Mediterranean diet in human health.

Variables Influencing Adoption of Practice-Based Guidelines in Canadian Renal Dietetic Practice - Corrected Proof

2009-10-05

Objective: We sought to determine the variables influencing the adoption of practice-based guidelines by Canadian renal registered dietitians (RRDs) for the identification and treatment of protein-energy malnutrition (PEM) in adult patients with chronic kidney disease on dialysis.Design: A web-based, cross-country survey was distributed to 288 RRDs via the Canadian Association of Renal Dietitians. The survey consisted of open-ended and close-ended questions addressing variables (facilitators and barriers) influencing RRDs' adoption of evidenced-based practice guidelines (EBPGs), along with questions related to practitioner practice (focused on organization, practitioners, and patients).Results: Seventy-four (51 full and seven partial) RRDs responded to the survey (for a 25% response rate); 16 responses not meeting the inclusion criteria were excluded from data analysis. Whereas 97% of respondents reported guideline utilization in daily practice, only 24% (n=14) used all of the recommendations within the EBPGs used by RRDs for the identification and treatment of PEM in adults on dialysis. The most commonly cited reasons for using EBPGs were perceived clinical benefits to the patient, and the applicability of guideline recommendations to daily practice. The most common barriers to the adoption of EBPGs were organizational (lack of time or staff and healthcare team support) and practitioner-based (practitioner-perceived conflicts regarding the evidence).Conclusions: The variables influencing RRDs' adoption of EBPGs were multifactorial (organizationally focused, practitioner-focused, and patient-focused). The development of up-to-date EBPGs for the identification and treatment of PEM in adult patients is urgently needed. The examination of these variables is important to ensure that EBPGs are feasible, applicable, and evidence-based.