Pathophysiology of protein-energy wasting in chronic renal failure

Identification of molecular biomarkers in human serum for chronic kidney disease using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy

Chronic kidney disease (CKD) and its progression to end-stage renal disease (ESRD) represent significant global health challenges, contributing to increased morbidity and mortality. Despite the potential diagnostic value of ATR-FTIR spectroscopic analysis of serum in CKD, research in this area remains limited. This study addressed this gap by aiming to explore the spectral profiles of sera obtained from hemodialysis patients and healthy controls. We investigated serum spectral profiles from 21 hemodialysis patients and 21 age/sex-matched controls using ATR-FTIR spectroscopy in the mid-infrared region (4000-400 cm-1). Spectroscopic analysis revealed elevated spectral intensity in ESRD samples compared to controls. Principal Component Analysis (PCA) successfully distinguished ESRD from control samples across multiple spectral regions (1480-900 cm-1, 1800-900 cm-1, and combined 3000-2800/1800-900 cm-1). Partial Least Squares Discriminant Analysis (PLS-DA) demonstrated enhanced group separation, with the optimized PLS model achieving perfect classification metrics (100% accuracy, sensitivity, and specificity). The combined spectral region models exhibited superior diagnostic performance compared to other regions. The analysis identified key molecular biomarkers associated with ESRD, including alterations in lipids, protein structures (represented by amide I and II bands), carbohydrates, nucleic acids, and immunoglobulins, which correlate with known biochemical changes in CKD pathophysiology. These findings demonstrate that ATR-FTIR spectroscopy with multivariate analysis is a rapid, cost-effective screening tool for CKD. The identified spectral biomarkers provide insights into disease-related biochemical alterations, adding valuable data to the research in this field.

Consensus Report on the Use of Continuous Glucose Monitoring in Chronic Kidney Disease and Diabetes

This report represents the conclusions of 15 experts in nephrology and endocrinology, based on their knowledge of key studies and evidence in the field, on the role of continuous glucose monitors (CGMs) in patients with diabetes and chronic kidney disease (CKD), including those receiving dialysis. The experts discussed issues related to CGM accuracy, indications, education, clinical outcomes, quality of life, research gaps, and barriers to dissemination. Three main goals of management for patients with CKD and diabetes were identified: (1) greater use of CGMs for better glycemic monitoring and management, (2) further research evaluating the accuracy, feasibility, outcomes, and potential value of CGMs in patients with end-stage kidney disease (ESKD) on hemodialysis, and (3) equitable access to CGM technology for patients with CKD. The experts also developed 15 conclusions regarding the use of CGMs in this population related to CGMs' unique delivery of both real-time information that can guide monitoring and management of glycemia and continuous and predictive data in this population, which is at higher risk for hypoglycemia and hyperglycemia. The group noted three major clinical gaps: (1) CGMs are not routinely prescribed for patients with diabetes and CKD; (2) CGMs are not approved by the United States Food and Drug Administration (FDA) for patients with diabetes who are on dialysis; and (3) CGMs are not routinely available to all of those who need them because of structural barriers in the health care system. These gaps can be improved with greater stakeholder collaboration, education, and awareness brought to the use of CGM technology in CKD.

Case Studies of Intradialytic Total Parenteral Nutrition in Nocturnal Home Hemodialysis

The standard use of intradialytic parenteral nutrition has yielded heterogeneous clinical results. Confounders include patient selection, limited dialysis sessional duration, and frequency. Nocturnal home hemodialysis provides an intensive form of kidney replacement therapy (5 sessions per week and 8 hours per treatment). We present a series of 4 nocturnal home hemodialysis patients who required intradialytic total parenteral nutrition (IDTPN) as their primary source of caloric intake. We describe the context, effectiveness, and complications of IDTPN in these patients. Our patients received a range of 1200 to 1590 kCal (including 60 to 70 g of amino acids) with each IDTPN session for up to 27 months. As the availability of home hemodialysis continues to grow, the role of supplemental or primary IDTPN will require further research for this vulnerable patient population.

Dietary Patterns and Perceptions in Older Adults With Chronic Kidney Disease in the Canadian Frailty Observation and Interventions Trial (CanFIT): A Mixed-Methods Study

Background:

People living with chronic kidney disease (CKD) have identified diet as an important aspect of their life and care. Understanding current consumption patterns in this population, and how they relate to patient perspectives of dietary recommendations, may help identify and design potential dietary intervention strategies in CKD.

Objective:

To investigate the dietary intake patterns of people with advanced-stage CKD, as well as subjective perspectives regarding dietary recommendations from participants and their caregivers.

Design:

Mixed-methods study with a sequential explanatory design.

Setting:

Manitoba, Canada.

Participants:

Individuals with late-stage CKD (CKD stages G4-G5, including dialysis) participating in the Canadian Frailty Observation and Interventions Trial (CanFIT).

Methods:

First, quantitative data were collected via a cross-sectional dietary assessment, using three 24-hour dietary recalls, a 36-question short diet questionnaire (SDQ), and a Nutrition Quality of Life (NQoL) tool (n = 59). Second, qualitative data were collected during 2 focus groups (n₁ = 12 and n₂ = 7) held with a subsample of individuals who had completed the dietary surveys, along with their caregivers. Focus groups explored topics related to diet and CKD; transcribed data were analyzed thematically. In the interpretation stage, the qualitative findings were combined with the quantitative results to help explain the latter and reach a deeper understanding of the subjective experiences of adults with CKD.

Results:

Quantitatively, nearly all (48/51; 94%) participants (mean age 70.8 ± 10.8 years) reported energy intakes below recommendations and most (86%) did not achieve recommended fiber intake. In addition, 15/21 (71%) of patients on dialysis had low protein intake. Qualitatively, 2 themes were identified: (1) Lacking/Needing dietary guidance—incomplete “information overload,” and (2) Experiencing difficulty in adapting to restrictions. Within the former theme, participants spoke of getting too much information at once, often at the wrong time. Within the latter theme, participants spoke of a loss of appetite, and cheating on their dietary recommendations.

Limitations:

Potential recall bias recalling dietary patterns, small sample size limiting generalizability, self-selection bias.

Conclusion:

Despite the reported lifestyle changes made by individuals with CKD, which negatively impacted their lives, many had suboptimal nutrition, especially in terms of energy and fiber. In addition, those on dialysis were not eating enough protein, which could be due to changing dietary recommendations as CKD progresses. Qualitative findings provided additional insight into how requisite CKD-dietary changes were perceived and how participants coped with these changes. The timing and delivery of the dietary education within CKD care in Manitoba may not be working for people with CKD as they progress through the disease.

Toward Revision of the ‘Best Practice for Diabetic Patients on Hemodialysis 2012’

Diabetic nephropathy is the leading cause of dialysis therapy worldwide. The number of diabetes patients on dialysis in clinical settings has been increasing in Japan. In 2013, the Japanese Society for Dialysis Therapy (JSDT) published the “Best Practice for Diabetic Patients on Hemodialysis 2012”. While glycated hemoglobin (HbA1c) is used mainly as a glycemic control index for dialysis patients overseas, Japan is the first country in the world to use glycated albumin (GA) for assessment. According to a survey conducted by the JSDT in 2018, the number of facilities measuring only HbA1c has decreased compared with 2013, while the number of facilities measuring GA or both has significantly increased. Ten years have passed since the publication of the first edition of the guidelines, and several clinical studies regarding the GA value and mortality of dialysis patients have been reported. In addition, novel antidiabetic agents have appeared, and continuous glucose monitoring of dialysis patients has been adopted. On the other hand, Japanese dialysis patients are rapidly aging, and the proportion of patients with malnutrition is increasing. Therefore, there is great variation among diabetes patients on dialysis with respect to their backgrounds and characteristics. This review covers the indices and targets of glycemic control, the treatment of hyperglycemia, and diet recommendations for dialysis patients with diabetes.

The Mutual Contribution of 3-NT, IL-18, Albumin, and Phosphate Foreshadows Death of Hemodialyzed Patients in a 2-Year Follow-Up

Patients with chronic kidney disease (CKD), especially those who are hemodialyzed (HD), are at significantly high risk of contracting cardiovascular disease and having increased mortality. This study aimed to find potential death predictors, the measurement of which may reflect increased mortality in HD patients, and then combine the most promising ones in frames of a simple death risk assessment model. For this purpose, HD patients (n=71) with acute myocardial infarction in the last year (HD group) and healthy people (control group) as a comparative group (n=32) were included in the study. Various laboratory determinations and non-invasive cardiovascular tests were performed. Next, patients were followed for two years, and data on cardiovascular (CV) deaths were collected. On this basis, two HD groups were formed: patients who survived (HD-A, n=51) and patients who died (HD-D, n=20). To model HD mortality, 21 out of 90 potential variables collected or calculated from the raw data were selected. The best explanatory power (95.5%) was reached by a general linear model with four variables: interleukin 18, 3-nitrotyrosine, albumin, and phosphate. The interplay between immuno-inflammatory processes, nitrosative and oxidative stress, malnutrition, and calcium-phosphate disorders has been indicated to be essential in predicting CV-related mortality in studied HD patients. ClinicalTrials.gov Identifier: NCT05214872.

Assessment of uremic sarcopenia in dialysis patients: An update

Uremic sarcopenia, which is highly prevalent in dialysis patients, leads to an increased risk of adverse outcomes, such as poor quality of life, falls, fracture, hospitalization, and even mortality. Therefore, early detection of uremic sarcopenia is crucial for administering quick and adequate multidisciplinary therapy to improve clinical outcomes. This review updates the current information about uremic sarcopenia assessment in chronic dialysis patients. We discuss the methods of assessing skeletal muscle mass, strength, and physical performance. We also discuss surrogate markers derived from serum and dialysate creatinine, in addition to emerging screening tools. The prevalence, clinical relevance, and impact of uremic sarcopenia on survival are reviewed and we discuss the limitations and challenges in applying the current working definition of sarcopenia based on the senior population to dialysis patients. The review shows that dialysis patients with skeletal muscle weakness or poor physical performance, either with or without low skeletal muscle mass, should undergo multidisciplinary therapy, included nutritional counseling, lifestyle modification, and exercise intervention, to mitigate the detrimental effects of uremic sarcopenia.

Nutritional Adequacy of Animal-Based and Plant-Based Asian Diets for Chronic Kidney Disease Patients: A Modeling Study

Plant-based low protein diets (LPDs) have gained popularity for managing chronic kidney disease (CKD) patients. The nutritional adequacy of these and other LPDs prescribed for CKD patients have not been carefully examined. This study assessed the nutrient composition of such LPDs and moderately high protein diets (MHPDs) that might be prescribed for patients in the Asia Pacific region with CKD who are not dialyzed or undergoing maintenance dialysis. Conventional diets containing at least 50% animal-based proteins and plant-based diets were also planned with protein prescriptions of 0.5 to 0.8 g/kg/day and MHPDs with protein prescriptions of 1.0 to 1.2 g/kg/day. Plant-based, lacto-, ovo-, and lacto-ovo-vegetarian and vegan LPDs and MHPDs were planned by replacing some or all of the animal proteins from the conventional diet. With 0.5 g protein/kg/day, all diets were below the Recommended Dietary Allowances (RDA) for at least one essential amino acid (EAA). At a protein prescription of 0.6 g/kg/day, only the conventional LPD met the RDA for all EAAs. This deficiency with the plant-based LPDs persisted even with several plant food substitutions. With a protein prescription ≥0.7 g/kg/day, all the plant-based and vegetarian LPDs provided the RDA for all EAA. The plant-based and vegetarian diets also contained relatively greater potassium, phosphorus, and calcium content but lower long-chain n-3 polyunsaturated fatty acids and vitamin B-12 than the conventional diet. Other essential micronutrients were commonly below the RDA even at higher protein intakes. The low contents of some essential micronutrients were found in both animal-based and plant-based diets. Prescription of all LPDs for CKD patients, especially plant-based and vegetarian LPDs, requires careful planning to ensure the adequacy of all nutrients, particularly essential amino acids. Consideration should be given to supplementing all animal-based and plant-based LPDs and MHPDs with multivitamins and certain trace elements.

Relationship between Circulating Galectin-3, Systemic Inflammation, and Protein-Energy Wasting in Chronic Hemodialysis Patients

Galectin-3 reportedly participates in the inflammatory process that causes insulin resistance in the target tissues. However, the role of high plasma galectin-3 levels as an indicator of protein-energy wasting (PEW) in patients undergoing maintenance hemodialysis remains unclear. This study included 240 hemodialysis patients (64.5 [55.3−74.0] years, 35.8% women) from a tertiary medical center. A baseline assessment of demographic and clinical data, biochemical parameters, and body composition was conducted. Plasma galectin-3 and other biomarkers were measured using a multiplex bead-based immunoassay. Participants were then divided into two subgroups depending on the median value of plasma galectin-3. Malnutrition was identified using the geriatric nutritional risk index (GNRI) and the criteria of the International Society of Renal Nutrition and Metabolism. Independent risk factors for elevated plasma galectin-3 and malnutrition were identified by multivariate logistic regression. The high galectin-3 group was more likely to be older, have lower lean tissue mass and GNRI scores, be diagnosed with PEW, dialyze through a tunneled catheter, and have higher circulating IL-6, TNF-α, and MCP-1 concentrations than the low galectin-3 group. After multivariate adjustment, only low mean arterial pressure, dialyzing with tunneled cuffed catheters, and elevated systemic inflammatory markers correlated with high galectin-3 levels. Plasma galectin-3 concentrations also increased significantly in hemodialysis patients with PEW. However, compared with other commonly used nutritional indicators, galectin-3 did not show superiority in predicting PEW. Although the plasma galectin-3 levels correlated with PEW severity, this correlation disappeared after adjustment for potential confounding variables (OR, 1.000; 95% CI, 0.999–1.001). In conclusion, plasma galectin-3 is a valuable biomarker for systemic inflammation but is less prominent for PEW in patients with maintenance hemodialysis. Further identification of novel biomarkers is required to detect patients at risk for malnutrition and implement appropriate interventions.

Optimal blood pressure for the minimum all-cause mortality in Chinese ESRD patients on maintenance hemodialysis

Blood pressure (BP) is a known prognostic marker for mortality in patients on maintenance hemodialysis (MHD). However, definition of the BP and its optimal values vary essentially among different MHD populations. Our purpose was to clarify these important clinical parameters in a Chinese MHD cohort. Accordingly, we reviewed the available records of patients on regular MHD during the past 10 years and made a comparison between the deceased (n=81) and survival ones (n=131). Multiple logistic regression and Kaplan–Meier survival analysis were used to examine the effect of BP on mortality and long-term survival, respectively. The all-cause mortality in our patients was 38.2%, in which 49.4% was from cardio-cerebrovascular deaths. Using the multiple logistic regression, we found that the sitting (the same definition hereafter) pre-dialysis systolic BP (SBP) was significantly associated with both the all-cause mortality and cardio-cerebrovascular deaths exclusively in patients of 60–80 years. Moreover, a pre-dialysis SBP of 140–160 mmHg in these patients had the minimum all-cause mortality (23.5%) against that conferred by either a lower (42.1%) or higher SBP value (61.5%). This observation was further confirmed by the Kaplan–Meier survival analysis. As fresh gain to the practice of hemodialysis, our report revealed that BP worked in a time-dependent way among a Chinese MHD cohort and highlighted a U-shaped association between the pre-dialysis SBP and all-cause mortality. These findings may hence help to obtain optimal BP control for better survival and lend some prognostic insight into mortality in these MHD patients.

Creatine homeostasis and protein energy wasting in hemodialysis patients

Muscle wasting, low protein intake, hypoalbuminemia, low body mass, and chronic fatigue are prevalent in hemodialysis patients. Impaired creatine status may be an often overlooked, potential contributor to these symptoms. However, little is known about creatine homeostasis in hemodialysis patients. We aimed to elucidate creatine homeostasis in hemodialysis patients by assessing intradialytic plasma changes as well as intra- and interdialytic losses of arginine, guanidinoacetate, creatine and creatinine. Additionally, we investigated associations of plasma creatine concentrations with low muscle mass, low protein intake, hypoalbuminemia, low body mass index, and chronic fatigue. Arginine, guanidinoacetate, creatine and creatinine were measured in plasma, dialysate, and urinary samples of 59 hemodialysis patients. Mean age was 65 ± 15 years and 63% were male. During hemodialysis, plasma concentrations of arginine (77 ± 22 to 60 ± 19 μmol/L), guanidinoacetate (1.8 ± 0.6 to 1.0 ± 0.3 μmol/L), creatine (26 [16–41] to 21 [15–30] μmol/L) and creatinine (689 ± 207 to 257 ± 92 μmol/L) decreased (all P < 0.001). During a hemodialysis session, patients lost 1939 ± 871 μmol arginine, 37 ± 20 μmol guanidinoacetate, 719 [399–1070] μmol creatine and 15.5 ± 8.4 mmol creatinine. In sex-adjusted models, lower plasma creatine was associated with a higher odds of low muscle mass (OR per halving: 2.00 [1.05–4.14]; P = 0.04), low protein intake (OR: 2.13 [1.17–4.27]; P = 0.02), hypoalbuminemia (OR: 3.13 [1.46–8.02]; P = 0.008) and severe fatigue (OR: 3.20 [1.52–8.05]; P = 0.006). After adjustment for potential confounders, these associations remained materially unchanged. Creatine is iatrogenically removed during hemodialysis and lower plasma creatine concentrations were associated with higher odds of low muscle mass, low protein intake, hypoalbuminemia, and severe fatigue, indicating a potential role for creatine supplementation.

Protein-Energy Wasting and Associated Factors Among Chronic Kidney Disease Patients at St. Paul's Hospital Millennium Medical College, Addis Ababa, Ethiopia

Background

Protein-energy wasting is a major issue in patients with chronic kidney disease (CKD), adversely affecting morbidity, mortality, functional activity, and quality of life. Assessment of nutritional status in CKD patients is important to ensure patient's normal protein stores and avoid metabolic complications. However, in Ethiopia, there were very few studies done to assess the prevalence of protein-energy wasting (PEW) and its associated factors among CKD patients.

Objective

To assess protein-energy wasting and associated factors among chronic kidney disease patients at adult OPD St. Paulo's Hospital Millennium Medical College, Addis Ababa Ethiopia.

Materials and Methods

An institution-based cross-sectional study was conducted from March to April 2019. Data were collected using a structured interviewer-administered questionnaire and anthropometric measurements, and laboratory data were collected from patient files. Data were entered into Epi-data version 3.1 and analyzed using SPSS version 20. Both bivariate and multiple logistic regression analyses were performed to identify associated factors. P values <0.05 were considered to declare statistical significance.

Results

In this study, 274 respondents were interviewed with a response rate of 100%. The prevalence of protein-energy wasting in CKD patients was 23.4%. Chronic kidney disease patients at age ≥65 years were seven times more likely to have protein-energy wasting as compared to patients aged 18-34 years [AOR=7.0, 95% (CI: 2.4, 20.5)]. Patients who had a history of anorexia were 5.2 times more likely to have protein-energy wasting as compared to those who had no history of anorexia [(AOR=5.2, 95% (CI: 2.7, 10.3)] and were significantly associated with the risk of having CKD.

Conclusion

The prevalence of protein-energy wasting among CKD patients was high and associated with age, physical activity, history of anorexia, and CKD stages. Interventions that address nutritional problems and lifestyle factors in CKD patients need to be implemented together with medical treatment.

Chronic Kidney Disease as Oxidative Stress- and Inflammatory-Mediated Cardiovascular Disease

Generating reactive oxygen species (ROS) is necessary for both physiology and pathology. An imbalance between endogenous oxidants and antioxidants causes oxidative stress, contributing to vascular dysfunction. The ROS-induced activation of transcription factors and proinflammatory genes increases inflammation. This phenomenon is of crucial importance in patients with chronic kidney disease (CKD), because atherosclerosis is one of the critical factors of their cardiovascular disease (CVD) and increased mortality. The effect of ROS disrupts the excretory function of each section of the nephron. It prevents the maintenance of intra-systemic homeostasis and leads to the accumulation of metabolic products. Renal regulatory mechanisms, such as tubular glomerular feedback, myogenic reflex in the supplying arteriole, and the renin-angiotensin-aldosterone system, are also affected. It makes it impossible for the kidney to compensate for water-electrolyte and acid-base disturbances, which progress further in the mechanism of positive feedback, leading to a further intensification of oxidative stress. As a result, the progression of CKD is observed, with a spectrum of complications such as malnutrition, calcium phosphate abnormalities, atherosclerosis, and anemia. This review aimed to show the role of oxidative stress and inflammation in renal impairment, with a particular emphasis on its influence on the most common disturbances that accompany CKD.

Association between serum soluble (pro)renin receptor level and worsening of cardiac function in hemodialysis patients: A prospective observational study

The (pro)renin receptor ((P)RR) is cleaved to generate soluble (P)RR (s(P)RR), which reflects the status of the tissue renin-angiotensin system. Hemodialysis (HD) patients have a poor prognosis due to the increased prevalence of cardiovascular diseases. The present study aimed to investigate whether serum s(P)RR level is associated with the worsening of cardiac function in HD patients. A total of 258 maintenance HD patients were recruited and serum s(P)RR concentration was measured. Background factors in patients who survived (S group) and patients who died (D group) during the 12-month follow-up period and relationships between serum s(P)RR level and changes in cardiac function during the follow-up period in the S group were investigated. The median serum s(P)RR value at baseline was 29.8 ng/ml. Twenty-four patients died during the follow-up period. Cardiothoracic ratio, human atrial natriuretic peptide (hANP), brain natriuretic peptide (BNP), and E over e-prime were significantly higher in the D group. In the S group, changes in hANP or BNP were significantly greater in the higher serum s(P)RR group than in the lower serum s(P)RR group. High serum s(P)RR level was significantly correlated with changes in BNP, independent of other factors. High serum s(P)RR level was associated with increases in BNP, independent of other risk factors, suggesting that an increased expression of (P)RR may be associated with a progression of heart failure in HD patients and that serum s(P)RR concentration could be used as a biomarker for selecting patients requiring intensive care.

End-Stage Renal Disease Patients Lose a Substantial Amount of Amino Acids during Hemodialysis

BACKGROUND

Poor nutritional status is frequently observed in end-stage renal disease patients and associated with adverse clinical outcomes and increased mortality. Loss of amino acids (AAs) during hemodialysis (HD) may contribute to protein malnutrition in these patients.

OBJECTIVE

We aimed to assess the extent of AA loss during HD in end-stage renal disease patients consuming their habitual diet.

METHODS

Ten anuric chronic HD patients (mean ± SD age: 67.9 ± 19.3 y, BMI: 23.2 ± 3.5 kg/m2), undergoing HD 3 times per week, were selected to participate in this study. Spent dialysate was collected continuously and plasma samples were obtained directly before and after a single HD session in each participant. AA profiles in spent dialysate and in pre-HD and post-HD plasma were measured through ultra-performance liquid chromatography to determine AA concentrations and, as such, net loss of AAs. In addition, dietary intake before and throughout HD was assessed using a 24-h food recall questionnaire during HD. Paired-sample t tests were conducted to compare pre-HD and post-HD plasma AA concentrations.

RESULTS

During an HD session, 11.95 ± 0.69 g AAs were lost via the dialysate, of which 8.26 ± 0.46 g were nonessential AAs, 3.69 ± 0.31 g were essential AAs, and 1.64 ± 0.17 g were branched-chain AAs. As a consequence, plasma total and essential AA concentrations declined significantly from 2.88 ± 0.15 and 0.80 ± 0.05 mmol/L to 2.27 ± 0.11 and 0.66 ± 0.05 mmol/L, respectively (P < 0.05). AA profiles of pre-HD plasma and spent dialysate were similar. Moreover, AA concentrations in pre-HD plasma and spent dialysate were strongly correlated (Spearman's ρ = 0.92, P < 0.001).

CONCLUSIONS

During a single HD session, ∼12 g AAs are lost into the dialysate, causing a significant decline in plasma AA concentrations. AA loss during HD can contribute substantially to protein malnutrition in end-stage renal disease patients. This study was registered at the Netherlands Trial Registry (NTR7101).

Cachexia/Protein energy wasting syndrome in CKD: Causation and treatment

Cachexia is a multifactorial syndrome defined by significant body weight loss, fat and muscle mass reduction, and increased protein catabolism. Protein energy wasting (PEW) is characterized as a syndrome of adverse changes in nutrition and body composition being highly prevalent in patients with CKD, especially in those undergoing dialysis, and it is associated with high morbidity and mortality in this population. Multiple mechanisms are involved in the genesis of these adverse nutritional changes in CKD patients. There is no obvious distinction between PEW and cachexia from a pathophysiologic standpoint and should be considered as part of the spectrum of the same nutritional disorder in CKD with similar management approaches for prevention and treatment based on current understanding. A plethora of factors can affect the nutritional status of CKD patients requiring a combination of therapeutic approaches to prevent or reverse protein and energy depletion. At present, there is no effective pharmacologic intervention that prevents or attenuates muscle atrophy in catabolic conditions like CKD. Prevention and treatment of uremic muscle wasting involve optimal nutritional support, correction of acidosis, and physical exercise. There has been emerging consistent evidence that active treatment, perhaps by combining nutritional interventions and resistance exercise, may be able to improve but not totally reverse or prevent the supervening muscle wasting and weakness. Active research into more direct pharmacological treatment based on basic mechanistic research is much needed for this unmet medical need in patients with CKD.

Urotensin II Induces Mice Skeletal Muscle Atrophy Associated with Enhanced Autophagy and Inhibited Irisin Precursor (Fibronectin Type III Domain Containing 5) Expression in Chronic Renal Failure

BACKGROUND/AIMS

Skeletal muscle atrophy is one of the main manifestations of protein energy wasting. We hypothesized that urotensin II (UII) can lead to skeletal muscle atrophy through upregulating autophagy and affecting Irisin precursor fibronectin type III domain containing 5 (FNDC5) expressions.

METHODS

Three animal models (the sham operation, wild-type C57BL/6 mice with 5/6 nephrectomy, UII receptor (UT) gene knockout (UTKO) mice with 5/6 nephrectomy) were designed. Skeletal muscle weight, cross-sectional area (CSA) along with UII, FNDC5, LC3, and p62 expression were investigated. C2C12 cells were differentiated for up to 4 days into myotubes. These cells were then exposed to different UII concentrations (10-5 to 10-7 M) for 6-12 h and analyzed for the expressions of autophagic markers. These cells were also exposed to the same predetermined UII concentrations for 48-72 h and analyzed for the FNDC5 expression. Myotube diameter was measured.

RESULTS

Upregulation of UII expression in skeletal muscle tissue was accompanied by reduced muscle weight and skeletal muscle CSA in the 2 posterior limbs, upregulated autophagy markers expression, and downregulated FNDC5 expression in 5/6 nephrectomy mice. The decrease of skeletal muscle weight, skeletal muscle CSA, downregulation of FNDC5 expression, and the upregulation of autophagy markers were inhibited in UTKO with 5/6 nephrectomy mice. Our in vitrostudy showed that UII could directly decrease myotube diameter, induce autophagy markers upregulation, and inhibit expression of FNDC5. When UII receptor gene was interfered by UT-specific siRNA, UII induced autophagy markers upregulation and FNDC5 downregulation were inhibited.

CONCLUSION

We are the first to verify UII induces mice skeletal muscle atrophy associated with enhanced skeletal muscle autophagy and inhibited FNDC5 expression in chronic renal failure.

Complementary Biomarker Assessment of Components Absorbed from Diet and Creatinine Excretion Rate Reflecting Muscle Mass in Dialysis Patients

To prevent protein energy malnutrition (PEM) and accumulation of waste products, dialysis patients require diet adjustments. Dietary intake assessed by self-reported intakes often provides biased information and standard 24-h urinary excretion is inapplicable in dialysis patients. We aimed to assess dietary intake via a complementary, less biased biomarker method, and to compare this to dietary diaries. Additionally, we investigated the prospective association of creatinine excretion rate (CER) reflecting muscle mass with mortality. Complete intradialytic dialysate and interdialytic urinary collections were used to calculate 24-h excretion of protein, sodium, potassium, phosphate and creatinine in 42 chronic dialysis patients and compared with protein, sodium, potassium, and phosphate intake assessed by 5-day dietary diaries. Cox regression analyses were employed to investigate associations of CER with mortality. Mean age was 64 ± 13 years and 52% were male. Complementary biomarker assessed (CBA) and dietary assessed (DA) protein intake were significantly correlated (r = 0.610; p < 0.001), but there was a constant bias, as dietary diaries overestimated protein intake in most patients. Correlations were found between CBA and DA sodium intake (r = 0.297; p = 0.056), potassium intake (r = 0.312; p = 0.047) and phosphate uptake/intake (r = 0.409; p = 0.008). However, Bland-Altman analysis showed significant proportional bias. During a median follow-up of 26.6 (25.3–31.5) months, nine dialysis patients (23%) died. CER was independently and inversely associated with survival (HR: 0.59 (0.42–0.84); p = 0.003). Excretion measurements may be a more reliable assessment of dietary intake in dialysis patients, as this method is relatively free from biases known to exist for self-reported intakes. CER seems to be a promising tool for monitoring PEM.

Decrease of muscle strength in vascular access hand due to silent ischaemia

Background:

Creation of vascular access leads to considerable local haemodynamic changes with decreased hand perfusion. Distal limb tissues then represent a model of hand ischaemia effect on muscles. The aim of our study was to investigate how the presence of vascular access influences the hand muscle strength in end-stage renal disease patients.

Methods:

We included 52 chronically haemodialysed patients with upper limb access without clinical signs of hand ischaemia. Muscle strength was evaluated by dynamometry. Finger pressure was measured on the second and fourth fingers and averaged for further analysis. Thenar tissue oxygenation (rSO2) was analysed using near-infrared spectroscopy. All examinations were performed in both the hands. Basic laboratory analysis was added. Data were processed with unpaired t-test and correlation analysis.

Results:

Hands with dialysis access had lower values of handgrip strength (54.2 ± 29.1 lbs vs 48.6 ± 23.4 lbs, p = 0.0006), systolic finger pressure (127.1 ± 32.0 mmHg vs 101.4 ± 31.6 mmHg, p < 10−8) and of thenar rSO2 (45.8% ± 12.9% vs 42.5% ± 13.3%, p = 0.002). Muscle strength (handgrip) was directly related to the thenar oxygenation ( r = 0.36; p = 0.014) and to the finger systolic pressure ( r = 0.38; p = 0.007) on the access extremity. On the extremity without dialysis access, handgrip strength was inversely related to patient’s age ( r = −0.41, p = 0.003), dialysis vintage ( r = −0.32, p = 0.02) and red cell distribution width ( r = −0.37, p = 0.01).

Conclusion:

The presence of dialysis access leads to the decrease of finger pressure, oxygenation, and also muscle strength even in the absence of clinically overt hand ischaemia. All these parameters are interrelated. This study underlines the consequences of inadequate muscle perfusion.

Children tolerate intradialytic oral nutrition

BACKGROUND

People undergoing haemodialysis (HD) often have poor nutrition, which in turn can contribute to worse outcomes. Inadequate nutrition has a particularly deleterious effect on growth and neurocognitive development, as well as mortality, in children and adolescents. Nutritional supplementation can improve outcomes but can be difficult to administer.

OBJECTIVE

Determine the tolerability of intradialytic oral nutrition in children and adolescents.

DESIGN

A cross-sectional quality improvement study in an outpatient paediatric HD unit. Intervention was intradialytic oral nutritional supplementation provided as protein bars and/or meals.

SUBJECTS

Children and adolescents undergoing outpatient HD who were able to participate in surveys and eat by mouth.

MEASUREMENTS

Adverse effects and symptoms on nurse- and patient-reported surveys, respectively. Relationships between the predictor variables and the outcomes were assessed using generalised estimating equations.

RESULTS

The majority of children felt better after eating on dialysis (72%) with no adverse effects (80%). On unadjusted analyses and confirmed with generalised estimating equation modelling, children who reported being hungry felt better after eating on dialysis, despite being more likely to have adverse effects.

CONCLUSION

The study demonstrates that our children and adolescents feel better after eating on HD with minimal adverse effects. The finding that hungry patients are more likely to feel better despite having a higher likelihood of an adverse effect demonstrates the tolerability of eating on HD. Intradialytic oral nutrition could be a safe and well-tolerated opportunity to provide supplemental nutrition to paediatric HD patients and improve outcomes.

Association between changes in quality of life and mortality in hemodialysis patients: results from the DOPPS

Background

Cross-sectional health-related quality of life (HR-QOL) measures are associated with mortality in hemodialysis (HD) patients. The impact of changes in HR-QOL on outcomes remains unclear. We describe the association of prior changes in HR-QOL with subsequent mortality among HD patients.

Methods

A total of 13 784 patients in the Dialysis Outcomes and Practice Patterns Study had more than one measurement of HR-QOL. The impact of changes between two measurements of the physical (PCS) and mental (MCS) component summary scores of the SF-12 on mortality was estimated with Cox regression.

Results

Mean age was 62 years (standard deviation: 14 years); 59% were male and 32% diabetic. Median time between HR-QOL measurements was 12 months [interquartile range (IQR): 11, 14]. Median initial PCS and MCS scores were 37.5 (IQR: 29.4, 46.2) and 46.4 (IQR: 37.2, 54.9); median changes in PCS and MCS scores were -0.2 (IQR: -5.5, 4.7) and -0.1 (IQR: -6.8, 5.9), respectively. The adjusted hazard ratio (HR) for a 5-point decline in HR-QOL score was 1.09 [95% confidence interval (CI): 1.06-1.12] for PCS and 1.05 (95% CI: 1.03-1.08) for MCS. Adjusting for the second QOL score, the change was not associated with mortality: HR = 1.01 (95% CI: 0.98-1.05) for delta PCS and 1.01 (95% CI: 0.98-1.03) for delta MCS. Categorizing the first and second scores as predictors, only the second PCS or MCS score was associated with mortality.

Conclusions

In our study, only the most recent HR-QOL score was associated with mortality. Hence, the predictive power of a measurement of HR-QOL is not affected by changes in HR-QOL prior to that measurement; more frequent HR-QOL measurements are needed to improve the prediction of outcomes in HD. Further studies are needed to determine the optimal frequency and appropriate instrument to be used for serial measurements.

Longitudinal Associations among Renal Urea Clearance-Corrected Normalized Protein Catabolic Rate, Serum Albumin, and Mortality in Patients on Hemodialysis

BACKGROUND AND OBJECTIVES

There are inconsistent reports on the association of dietary protein intake with serum albumin and outcomes among patients on hemodialysis. Using a new normalized protein catabolic rate (nPCR) variable accounting for residual renal urea clearance, we hypothesized that higher baseline nPCR and rise in nPCR would be associated with higher serum albumin and better survival among incident hemodialysis patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Among 36,757 incident hemodialysis patients in a large United States dialysis organization, we examined baseline and change in renal urea clearance-corrected nPCR as a protein intake surrogate and modeled their associations with serum albumin and mortality over 5 years (1/2007-12/2011).

RESULTS

Median nPCRs with and without accounting for renal urea clearance at baseline were 0.94 and 0.78 g/kg per day, respectively (median within-patient difference, 0.14 [interquartile range, 0.07-0.23] g/kg per day). During a median follow-up period of 1.4 years, 8481 deaths were observed. Baseline renal urea clearance-corrected nPCR was associated with higher serum albumin and lower mortality in the fully adjusted model (Ptrend<0.001). Among 13,895 patients with available data, greater rise in renal urea clearance-corrected nPCR during the first 6 months was also associated with attaining high serum albumin (≥3.8 g/dl) and lower mortality (Ptrend<0.001); compared with the reference group (a change of 0.1-0.2 g/kg per day), odds and hazard ratios were 0.53 (95% confidence interval, 0.44 to 0.63) and 1.32 (95% confidence interval, 1.14 to 1.54), respectively, among patients with a change of <-0.2 g/kg per day and 1.62 (95% confidence interval, 1.35 to 1.96) and 0.76 (95% confidence interval, 0.64 to 0.90), respectively, among those with a change of ≥0.5 g/kg per day. Within a given category of nPCR without accounting for renal urea clearance, higher levels of renal urea clearance-corrected nPCR consistently showed lower mortality risk.

CONCLUSIONS

Among incident hemodialysis patients, higher dietary protein intake represented by nPCR and its changes over time appear to be associated with increased serum albumin levels and greater survival. nPCR may be underestimated when not accounting for renal urea clearance. Compared with the conventional nPCR, renal urea clearance-corrected nPCR may be a better marker of mortality.

Characteristics of a Pseudomonas aeruginosa induced porcine sepsis model for multi-organ metabolic flux measurements

Survival of sepsis is related to loss of muscle mass. Therefore, it is imperative to further define and understand the basic alterations in nutrient metabolism in order to improve targeted sepsis nutritional therapies. We developed and evaluated a controlled hyperdynamic severe sepsis pig model that can be used for in vivo multi-organ metabolic studies in a conscious state. In this catheterized pig model, bacteremia was induced intravenously with 109 CFU/h Pseudomonas aeruginosa (PA) in 13 pigs for 18 h. Both the PA and control (nine) animals received fluid resuscitation and were continuously monitored. We examined in detail their hemodynamics, blood gases, clinical chemistry, inflammation, histopathology and organ plasma flows. The systemic inflammatory response (SIRS) diagnostic scoring system was used to determine the clinical septic state. Within 6 h from the start of PA infusion, a septic state developed, as was reflected by hyperthermia and cardiovascular changes. After 12 h of PA infusion, severe sepsis was diagnosed. Disturbed cardiovascular function, decreased portal drained viscera plasma flow (control: 37.6 ± 4.6 mL/kg body weight (bw)/min; PA 20.3 ± 2.6 mL/kg bw/min, P < 0.001), as well as moderate villous injury in the small intestines were observed. No lung, kidney or liver failure was observed. Acute phase C-reactive protein (CRP) and interleukin-6 (IL-6) levels did not change in the PA group. However, significant metabolic changes such as enhanced protein breakdown, hypocalcemia and hypocholesterolemia were found. In conclusion, PA-induced bacteremia in a catheterized pig is a clinically relevant model for acute severe sepsis and enables the study of complex multi-organ metabolisms.

Nutritional status among peritoneal dialysis patients after oral supplement with ONCE dialyze formula

BACKGROUND

Malnutrition is an important problem in patients treated with long-term dialysis, and most dialysis patients have lower dietary energy and protein intake. This study was undertaken to examine whether orally administered Otsuka Nutrition Pharmaceutical (ONCE) dialyze formula (ODF) supplement would improve energy intake without mineral and electrolyte disturbances in patients with continuous ambulatory peritoneal dialysis (CAPD).

METHODS

The effects of ODF supplementation on nutrition markers including serum albumin and prealbumin concentrations and inflammatory stress in patients with chronic CAPD were evaluated. All patients received daily oral ODF supplements for 15 days. During follow-up, all patients were evaluated clinically and biochemically, and nutritional status was assessed.

RESULTS

Thirty patients with mean age 61.9±12.3 years and weekly Kt/V 2.2±0.4 were studied. The mean values for nutritional parameters included a body weight of 53.7±9.5 kg, a serum albumin level of 3.3±0.4 g/dL, a serum prealbumin level of 33.8±11.1 mg/dL, a dietary energy intake of 21.9±7.1 kcal/kg/day, and a dietary protein intake of 0.9±0.3 g/kg/day. After 15-day ODF treatment, these patients had significant dietary energy and protein, carbohydrate, fat, fiber, potassium, calcium, and magnesium intake from baseline (P<0.05). Furthermore, significant improvements were found in nutritional markers including body weight, blood urea nitrogen, and prealbumin levels, but no changes were observed in serum albumin and high-sensitivity C-reactive protein levels. At the end of follow-up, the frequency of patients with moderate malnutrition decreased from 24.2% to 18.2%, and no increased incidence was observed of hyperkalemia, hyperphosphatemia, and metabolic acidosis.

CONCLUSION

ODF supplementation ameliorates low dietary energy and nutrient intake as well as improves serum prealbumin and body weight in patients with long-term CAPD.

Nutritional Status Predicts 10-Year Mortality in Patients with End-Stage Renal Disease on Hemodialysis

Protein-energy wasting (PEW) is associated with mortality in patients with end-stage renal disease (ESRD) on maintenance hemodialysis. The correct diagnosis of PEW is extremely important in order to predict clinical outcomes. However, it is unclear which parameters should be used to diagnose PEW. Therefore, this retrospective observational study investigated the relationship between mortality and nutritional parameters in ESRD patients on maintenance hemodialysis. A total of 144 patients were enrolled. Nutritional parameters, including body mass index, serum albumin, dietary intake, normalized protein catabolic rate (nPCR), and malnutrition inflammation score (MIS), were measured at baseline. Fifty-three patients died during the study. Survivors had significantly higher nPCR (1.10 ± 0.24 g/kg/day vs. 1.01 ± 0.21 g/kg/day; p = 0.048), energy intake (26.7 ± 5.8 kcal/kg vs. 24.3 ± 4.2 kcal/kg; p = 0.009) and protein intake (0.91 ± 0.21 g/kg vs. 0.82 ± 0.24 g/kg; p = 0.020), and lower MIS (5.2 ± 2.3 vs. 6.1 ± 2.1, p = 0.039). In multivariable analysis, energy intake <25 kcal/kg (HR 1.860, 95% CI 1.018–3.399; p = 0.044) and MIS > 5 (HR 2.146, 95% CI 1.173–3.928; p = 0.013) were independent variables associated with all-cause mortality. These results suggest that higher MIS and lower energy intake are harmful to ESRD patients on maintenance hemodialysis. Optimal energy intake could reduce mortality in these patients.

Impact of Malnutrition, Inflammation, and Atherosclerosis on the Outcome in Hemodialysis Patients

Malnutrition, inflammation, and atherosclerosis are significant problems in patients on hemodialysis. A prospective, observational study in 100 hemodialysis patients for 2 years was conducted. The primary outcomes were hospitalizations and mortality at the end of 2 years. The mean age was 61 ± 11.3 years and 69% were male. Seven patients did not complete the study (five underwent transplant and two were shifted to other units). Serum albumin was significantly lower in malnourished patients at 6 months from the beginning of the study period (3.58 vs. 3.79 g/dl, P = 0.001). Malnutrition based on subjective global assessment (SGA) was seen in 30 (32%) patients: mild to moderate in 27 (29%) and severe in 3 (3%). Inflammation was seen in 73 (78.5%) patients and intimal-medial thickness of >1.1 mm indicating significant atherosclerosis was seen in 73 (78.5%) patients. Modified SGA score and malnutrition-inflammation score (MIS) were significantly more in the malnourished group. Statistically significant association was seen between hospitalization and mortality in the malnourished population, and the odds ratio of death in malnourished patients was 9.83 (95% confidence interval: 2.8-34.3, P < 0.001). There was a moderate correlation between malnutrition assessed by modified SGA and MIS score (r = 0.54, P < 0.001). Mortality rate was 37% in patients with mild to moderate and 67% in severe malnutrition. Hospital admission was seen in 43 (46%) patients and was significantly more common in malnourished compared to well-nourished patients (77% vs. 32%, P < 0.001). Multiple logistic regression analysis showed that malnutrition by Modified SGA was the only significant variable associated with mortality at 2 years, and addition of MIS score did not improve the predictive ability of the model to modified SGA. We recommend the use of modified SGA and serial serum albumin to monitor nutrition in hemodialysis patients.

Changes in urine volume and serum albumin in incident hemodialysis patients

INTRODUCTION

Hypoalbuminemia is a predictor of poor outcomes in dialysis patients. Among hemodialysis patients, there has not been prior study of whether residual kidney function or decline over time impacts serum albumin levels. We hypothesized that a decline in residual kidney function is associated with an increase in serum albumin levels among incident hemodialysis patients.

METHODS

In a large national cohort of 38,504 patients who initiated hemodialysis during 1/2007-12/2011, we examined the association of residual kidney function, ascertained by urine volume and renal urea clearance, with changes in serum albumin over five years across strata of baseline residual kidney function, race, and diabetes using case-mix adjusted linear mixed effects models.

FINDINGS

Serum albumin levels increased over time. At baseline, patients with greater urine volume had higher serum albumin levels: 3.44 ± 0.48, 3.50 ± 0.46, 3.57 ± 0.44, 3.59 ± 0.45, and 3.65 ± 0.46 g/dL for urine volume groups of <300, 300-<600, 600-<900, 900-<1,200, and ≥1,200 mL/day, respectively (P_trend  < 0.001). Over time, urine volume and renal urea clearance declined and serum albumin levels rose, while the baseline differences in serum albumin persisted across groups of urinary volume. In addition, the rate of decline in residual kidney function was not associated with the rate of change in albumin.

DISCUSSION

Hypoalbuminemia in hemodialysis patients is associated with lower residual kidney function. Among incident hemodialysis patients, there is a gradual rise in serum albumin that is independent of the rate of decline in residual kidney function, suggesting that preservation of residual kidney function does not have a deleterious impact on serum albumin levels.

A practical approach to the nutritional management of chronic kidney disease patients in Cape Town, South Africa

Background

The multi-racial and multi-ethnic population of South Africa has significant variation in their nutritional habits with many black South Africans undergoing a nutritional transition to Western type diets. In this review, we describe our practical approaches to the dietary and nutritional management of chronic kidney disease (CKD) patients in Cape Town, South Africa.

Discussion

Due to poverty and socio-economic constraints, significant challenges still exist with regard to achieving the nutritional needs and adequate dietary counselling of many CKD patients (pre-dialysis and dialysis) in South Africa. Inadequate workforce to meet the educational and counselling needs of patients, inability of many patients to effectively come to terms with changing body and metabolic needs due to ongoing kidney disease, issues of adherence to fluid and food restrictions as well as adherence to medications and in some cases the inability to obtain adequate daily food supplies make up some of these challenges. A multi-disciplinary approach (dietitians, nurses and nephrologists) of regularly reminding and educating patients on dietary (especially low protein diets) and nutritional needs is practiced. The South African Renal exchange list consisting of groups of food items with the same nutritional content has been developed as a practical tool to be used by dietitians to convert individualized nutritional prescriptions into meal plan to meet the nutritional needs of patients in South Africa. The list is currently utilized in counselling CKD patients and provides varied options for food items within the same group (exchangeable) as well as offering ease for the description of suitable meal portions (sizes) to our patients.

Summary

Regular and continuous education of CKD patients by a multi-disciplinary team in South Africa enables our patients to meet their nutritional goals and retard CKD progression. The South African renal exchange list has proved to be a very useful tool in meeting this need.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-016-0297-4) contains supplementary material, which is available to authorized users.

APPETITE PREDICTS INTAKE AND NUTRITIONAL STATUS IN PATIENTS RECEIVING PERITONEAL DIALYSIS

BACKGROUND

Sub-optimal nutrition status is common amongst patients receiving peritoneal dialysis (PD) and leads to poor clinical outcome. This population experiences multi-factorial challenges to achieving optimal nutritional status, particularly driven by inadequate intake.

OBJECTIVES

The aim of this investigation was to identify factors associated with inadequate protein intake and sub-optimal nutritional status in patients undergoing PD.

DESIGN/PARTICIPANTS

This was a cross-sectional study of 67 adult patients receiving PD (mean age 59 ± 14 years; 57% male) within a single centre. Participants were consecutively recruited and interviewed by renal dietitians, collecting: Subjective Global Assessment (SGA); quality of life (using EQ-5D); dietary intake (via dietary interview); and appetite (using Appetite and Diet Assessment Tool). Participant demographics were obtained via survey or medical charts. Main outcome measures were inadequate dietary protein intake (<1.1 g/kg adjusted body weight/day) and malnutrition (as defined by SGA rating B or C).

RESULTS

Overall, 15 (22%) patients were malnourished and 29 (43%) had inadequate protein intake. Poor appetite (anorexia) was reported in 62% (18/29) of participants with inadequate protein malnourished patients reported anorexia versus 12 (23%) of the well-nourished patients (p = 0.0001).

CONCLUSION

Anorexia was a key risk factor for inadequate protein intake and malnutrition in patients undergoing PD. These findings highlight a need to closely monitor patients with appetite disturbances.

Dietary energy requirements in relatively healthy maintenance hemodialysis patients estimated from long-term metabolic studies

BACKGROUND

Studies that examined dietary energy requirements (DERs) of patients undergoing maintenance hemodialysis (MHD) have shown mixed results. Many studies reported normal DERs, but some described increased energy needs. DERs in MHD patients have been estimated primarily from indirect calorimetry and from nitrogen balance studies. The present study measured DERs in MHD patients on the basis of their dietary energy intake and changes in body composition.

OBJECTIVE

This study assessed DERs in MHD patients who received a constant energy intake while changes in their body composition were measured.

DESIGN

Seven male and 6 female sedentary, clinically stable MHD patients received a constant mean (±SD) energy intake for 92.2 ± 7.9 d while residing in a metabolic research ward. Changes in fat and fat-free mass, measured by dual-energy X-ray absorptiometry, were converted to calorie equivalents and added to energy intake to calculate energy requirements.

RESULTS

The average DER was 31 ± 3 kcal · kg(-1) · d(-1) calculated from energy intake and change in fat and fat-free calories, which was 28 ± 197 kcal/d over the 92 d of the study. DERs of MHD patients correlated strongly with their body weight (r = 0.81, P = 0.002) and less closely with their measured resting energy expenditure expressed as kcal/d (r = 0.69, P = 0.01). Although the average observed DER in MHD patients was similar to published estimated values for normal sedentary individuals of similar age and sex, there was wide variability in DER among individual patients (range: 26-36 kcal · kg(-1) · d(-1)).

CONCLUSIONS

Average DERs of sedentary, clinically stable patients receiving MHD are similar to those of sedentary normal individuals. Our data do not support the theory that MHD patients have increased DERs. Due to the high variability in DERs, careful monitoring of the nutritional status of individual MHD patients is essential. This trial was registered at clinicaltrials.gov as NCT02194114.

Self-Reported Interview-Assisted Diet Records Underreport Energy Intake in Maintenance Hemodialysis Patients

OBJECTIVES

Studies suggest that maintenance hemodialysis (MHD) patients report dietary energy intakes (EIs) that are lower than what is actually ingested. Data supporting this conclusion have several important limitations. The present study introduces a novel approach of assessing underreporting of EI in MHD patients.

DESIGN

Comparisons of EI of free-living MHD patients determined from food records to their measured energy needs.

SETTING

Metabolic research ward.

SUBJECTS

Thirteen clinically stable MHD patients with unchanging weights whose EI was assessed by dietitian interview-assisted 3-day food records.

INTERVENTION

EI was compared with (1) patients' resting energy expenditure (REE), measured by indirect calorimetry, and estimated total energy expenditure (TEE) and (2) patients' dietary energy requirements (DER) measured while patients underwent nitrogen balance studies and consumed a constant energy diet in a research ward for a mean duration of 89.5 days. DER was calculated as the actual EI during the research study corrected for changes in body fat and lean body mass measured by Dual X-Ray Absorptiometry.

MAIN OUTCOME MEASURE

Underreporting of EI was determined by an EI:REE ratio <1.27 and an EI:TEE ratio or EI:DEE ratio <1.0.

RESULTS

Seven of the 13 MHD patients studied were male. Patient's ages were 47.7 ± standard deviation 9.7 years; body mass index averaged 25.4 ± 2.8 kg/m2, and dialysis vintage was 53.3 ± 37.1 months. The EI:REE ratio (1.03 ± 0.23) was significantly less than the cutoff value for underreporting of 1.27 (P = .001); 12 of 13 patients had EI:REE ratios <1.27. The mean EI:TEE ratio was significantly less than the cutoff value of 1.0 (0.73 ± 0.17, P < .0001), and 12 MHD patients had EI:TEE ratios <1.0. The EI:DER ratio was also <1.0 (0.83 ± 0.25, P = .012), and 10 MHD had EI:DER ratios <1.0.

CONCLUSIONS

Dietitian interview-assisted diet records by MHD patients substantially underestimate the patient's dietary EI.

Effect of progressive resistance training on measures of skeletal muscle hypertrophy, muscular strength and health-related quality of life in patients with chronic kidney disease: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Skeletal muscle wasting resulting in reduced muscular strength and health-related quality of life (HR-QOL) is common in chronic kidney disease (CKD) and may be reversed with progressive resistance training (PRT). Therefore, we systematically assessed the effect of PRT on measures of skeletal muscle hypertrophy, muscular strength and HR-QOL in this cohort to inform clinical practice and guidelines.

DESIGN

We performed a systematic review and meta-analysis.

INCLUSION CRITERIA

We included randomised controlled trials (RCTs) that investigated the independent effect of PRT (>6 weeks) on measures of skeletal muscle hypertrophy [muscle mass or cross-sectional area (CSA)], muscular strength and/or HR-QOL in adults with CKD.

DATA EXTRACTION AND ANALYSIS

The standardised mean difference (SMD) from each study was pooled to produce an overall estimate of effect and associated 95% confidence interval (95% CI) between treatment and control groups on primary outcomes.

RESULTS

Seven RCTs in 271 patients with Stage 3-5 CKD yielded seven studies on muscular strength (N = 249), six studies on total body muscle mass (N = 200) and six studies on HR-QOL (N = 223). PRT significantly improved standardised muscular strength [SMD 1.15 (95% CI 0.80-1.49)] and HR-QOL [SMD 0.83 (95% CI 0.51-1.16)], but not total body muscle mass [SMD 0.29 (95% CI -0.27 to 0.86)] in our primary analysis. However, secondary analysis of six studies showed that PRT induced significant muscle hypertrophy of the lower extremities (leg mass, or mid-thigh or quadriceps CSA) [SMD 0.43 (95% CI 0.11-0.76)], a pertinent analysis given that most studies implemented lower-body PRT only.

CONCLUSIONS

Robust evidence from RCTs indicates that PRT can induce skeletal muscle hypertrophy and increase muscular strength and HR-QOL outcomes in men and women with CKD. Therefore, clinical practice guidelines should be updated to inform clinicians on the benefits of PRT in this cohort.

Nutrition and dietary intake and their association with mortality and hospitalisation in adults with chronic kidney disease treated with haemodialysis: protocol for DIET-HD, a prospective multinational cohort study

INTRODUCTION

Adults with end-stage kidney disease (ESKD) treated with haemodialysis experience mortality of between 15% and 20% each year. Effective interventions that improve health outcomes for long-term dialysis patients remain unproven. Novel and testable determinants of health in dialysis are needed. Nutrition and dietary patterns are potential factors influencing health in other health settings that warrant exploration in multinational studies in men and women treated with dialysis. We report the protocol of the "DIETary intake, death and hospitalisation in adults with end-stage kidney disease treated with HaemoDialysis (DIET-HD) study," a multinational prospective cohort study. DIET-HD will describe associations of nutrition and dietary patterns with major health outcomes for adults treated with dialysis in several countries.

METHODS AND ANALYSIS

DIET-HD will recruit approximately 10,000 adults who have ESKD treated by clinics administered by a single dialysis provider in Argentina, France, Germany, Hungary, Italy, Poland, Portugal, Romania, Spain, Sweden and Turkey. Recruitment will take place between March 2014 and June 2015. The study has currently recruited 8000 participants who have completed baseline data. Nutritional intake and dietary patterns will be measured using the Global Allergy and Asthma European Network (GA(2)LEN) food frequency questionnaire. The primary dietary exposures will be n-3 and n-6 polyunsaturated fatty acid consumption. The primary outcome will be cardiovascular mortality and secondary outcomes will be all-cause mortality, infection-related mortality and hospitalisation.

ETHICS AND DISSEMINATION

The study is approved by the relevant Ethics Committees in participating countries. All participants will provide written informed consent and be free to withdraw their data at any time. The findings of the study will be disseminated through peer-reviewed journals, conference presentations and to participants via regular newsletters. We expect that the DIET-HD study will inform large pragmatic trials of nutrition or dietary interventions in the setting of advanced kidney disease.

Malnutrition and its association with inflammation and vascular disease in children on maintenance dialysis

BACKGROUND

Malnutrition is associated with both inflammation and atherosclerotic cardiovascular disease in adults with chronic kidney disease. We studied the prevalence of malnutrition and its possible associations with inflammation and vascular disease in children on chronic dialysis.

METHODS

Thirty-three patients on maintenance dialysis (18 peritoneal dialysis, 15 hemodialysis) and 19 age- and gender- matched healthy controls were studied. Nutritional status was assessed by anthropometric measurements including body mass index (BMI), upper arm measurements, multifrequency bioimpedance analysis (BIA) and serum levels of albumin, prealbumin, and cholesterol. Inflammation was assessed by serum levels of C-reactive protein (CRP), interleukin (IL)-6, and tumor necrosis factor (TNF)-alpha. The carotid artery intima thickness (cIMT) was measured to assess vascular disease.

RESULTS

Compared with healthy children, patients had lower anthropometric measurements (P < 0.05) and serum albumin level (P < 0.001), and higher CRP and TNF-alpha (P = 0.030 and P = 0.007, respectively), and higher cIMT-SDS (P < 0.001). Malnutrition was present in 8 (24%) and lower BIA-based fat mass was independently associated with higher IL-6 levels (P = 0.035). An increased cIMT was present in 16 (48.5%); however, there was no difference in cIMT-SDS between patients with and without malnutrition. Carotid IMT did not show any association with nutritional indices; but positively correlated with serum IL-6 (P = 0.037), CRP (P = 0.012), and iPTH (P = 0.009), and independently associated with only iPTH (P = 0.018).

CONCLUSIONS

Children on dialysis are at an increased risk of malnutrition, inflammation, and vascular disease. Although each of these three conditions exists, there is no interaction among them all. We postulate that the malnutrition-inflammation-atherosclerosis (MIA) complex might not exist in pediatric dialysis patients.

Hepatoprotective and nephroprotective effects of Cnidoscolus aconitifolius in protein energy malnutrition induced liver and kidney damage

Introduction:

This study was designed to evaluate the ameliorative and hypocholesterolemic effects of dietary supplementation of Cnidoscolus aconitifolius leaf meal (CALM) on hepatic injury and kidney injury associated with protein energy malnutrition (PEM).

Materials and Methods:

In this study, PEM was induced in weaning male Wistar albino rats by feeding them with low protein diet for 2 weeks. The effects of several recovery diets containing 20% soya protein or 20% C. aconitifolius in place of soya protein or 10% soya proteins with 10% C. aconitifolius or commercial rat feed were assessed in PEM rats. Plasma biochemical parameters were assessed as well.

Results:

After the induction of PEM, results obtained showed significant increase in alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), total proteins (T.P), total bilirubin (T.Bil), triglycerides, total cholesterol, low density lipoproteins (LDL), blood urea nitrogen (BUN), and creatinine with significant reduction in plasma high density lipoproteins (HDL), albumin, sodium (Na⁺), potassium (K⁺), chloride (Cl⁻), bicarbonate (HC03⁻), and phosphate (P04²⁻) in PEM rats. Upon introduction of recovery diets containing 20% soya protein or 20% C. aconitifolius in place of soya protein or 10% soya proteins with 10% C. aconitifolius or commercial rat feed for 4 weeks caused significant (P < 0.05) reduction in plasma values of ALP, ALT, AST, T.bil, T.P., LDL, total cholesterol, triglycerides, BUN, creatinine, and significant increase in HDL and complete restoration of plasma electrolytes.

Conclusions:

C. aconitifolius in protein deficient diets has a protective role against hepatic injury and renal damage associated with PEM.

Urine creatinine excretion and clinical outcomes in CKD

BACKGROUND AND OBJECTIVES

Twenty-four-hour urine creatinine excretion is a reliable approximation of muscle mass. Whether changes in urine creatinine predict clinical outcomes in persons with CKD is unknown. This work studied the relationship between urine creatinine and patient and renal survival in people with CKD not requiring renal replacement therapy.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This longitudinal cohort study included incident stages 3-5 CKD patients referred to the renal clinic at the University Federico II in Naples between January of 1995 and December of 2005. Clinical data and urine creatinine were updated at each visit. Main outcomes were all-cause mortality and kidney failure requiring dialysis.

RESULTS

This study enrolled 525 individuals and followed them for a median of 6 years (range of 4 months to 15 years). Urine creatinine excretion declined by 16 mg/d per year (95% confidence interval, 14 to 19) in participants with CKD stages 3a, 3b, and 4, and it remained stable in participants with stage 5 CKD. Per each 20 mg/d decline in urine creatinine, mortality increased by 3% (adjusted hazard ratio, 1.03; 95% confidence interval, 1.01 to 1.05), and the risk of initiating dialysis increased by 2% (adjusted hazard ratio, 1.02; 95% confidence interval, 1.01 to 1.03). These associations were independent of body mass index and GFR.

CONCLUSIONS

In persons with CKD stages 3 and 4, urine creatinine declines at a rate of 16 mg/d per year. Lower urine creatinine excretion predicts greater risk of kidney failure and patient mortality.

Two-point normalized protein catabolic rate overestimates nPCR in pediatric hemodialysis patients

BACKGROUND

Normalized protein catabolic rate (nPCR) calculation depends on estimating the urea generation between consecutive hemodialysis (HD) treatments. Two-point nPCR using blood urea nitrogen (BUN) before and after the same HD treatment has not been validated in pediatric patients, who typically receive a more intense HD dose than adults. This study aimed to compare nPCR calculated with a two-point vs. a three-point nPCR model in pediatric HD patients.

METHODS

Pediatric patients receiving HD at 2 units were enrolled. Three BUN measurements were obtained around a midweek HD treatment: one prior to HD (preBUN1), one 30 s after HD (30sBUN), and one prior to the subsequent HD (preBUN2). The two-point nPCR model was calculated using preBUN1 and 30sBUN and the three-point nPCR model was calculated using preBUN2 and 30sBUN.

RESULTS

Seventy-six BUN sets from 35 patients were analyzed. Mean age was 16.4 ± 3.5 years. Mean dry weight was 51.4 ± 17.1 kg. Mean spKt/V was 1.54 ± 0.23. Mean preBUN2 was significantly lower than mean preBUN1 (60.2 ± 18.6 vs. 64.0 ± 18.9 mg/dl, p = 0.0001). nPCR obtained from the three-point model was significantly lower than nPCR obtained from the two-point model (1.07 ± 0.31 vs. 1.17 ± 0.31 g/kg/day, p = 0.00001). Seven of 76 (9.2 %) paired comparisons yielded three-point nPCR <1 vs. two-point nPCR >1.

CONCLUSIONS

Our data show that in pediatric patients receiving HD, the ((1) two-point and three-point models lead to significantly different nPCRs, and (2) inaccurate protein intake assessment may result from reliance on a two-point model for nPCR estimates.

Predicting erythropoietin resistance in hemodialysis patients with type 2 diabetes

Background

Resistance to ESAs (erythropoietin stimulating agents) is highly prevalent in hemodialysis patients with diabetes and associated with an increased mortality. The aim of this study was to identify predictors for ESA resistance and to develop a prediction model for the risk stratification in these patients.

Methods

A post-hoc analysis was conducted of the 4D study, including 1015 patients with type 2 diabetes undergoing hemodialysis. Determinants of ESA resistance were identified by univariate logistic regression analyses. Subsequently, multivariate models were performed with stepwise inclusion of significant predictors from clinical parameters, routine laboratory and specific biomarkers.

Results

In the model restricted to clinical parameters, male sex, shorter dialysis vintage, lower BMI, history of CHF, use of ACE-inhibitors and a higher heart rate were identified as independent predictors of ESA resistance. In regard to routine laboratory markers, lower albumin, lower iron saturation, higher creatinine and higher potassium levels were independently associated with ESA resistance. With respect to specific biomarkers, higher ADMA and CRP levels as well as lower Osteocalcin levels were predictors of ESA resistance.

Conclusions

Easily obtainable clinical parameters and routine laboratory parameters can predict ESA resistance in diabetic hemodialysis patients with good discrimination. Specific biomarkers did not meaningfully further improve the risk prediction of ESA resistance. Routinely assessed data can be used in clinical practice to stratify patients according to the risk of ESA resistance, which may help to assign appropriate treatment strategies.

Clinical trial registration

The study was registered at the German medical authority (BfArM; registration number 401 3206). The sponsor protocol ID and clinical trial unique identified number was CT-981-423-239. The results of the study are published and available at http://www.ncbi.nlm.nih.gov/pubmed/16034009.

Pathophysiological and clinical aspects of malnutrition in chronic renal failure

Kidney diseases are the ninth leading cause of death in the USA. In these patients cardiovascular mortality is greater than in the general population. This observation, not completely explained by the so-called 'traditional' cardiovascular risk factors, lead the authors to postulate other 'emerging' ones found in chronic renal failure patients. Among these new findings, nutritional status, considered as the balance existing between nutrient requirements and intakes, plays an important role for the development of cardiovascular diseases. In fact several nutritional parameters are widely known as pathophysiological determinants of cardiovascular disturbances, which are based on accelerated atherosclerosis, due especially to enhanced oxidative stress and endothelial dysfunction. Chronic renal failure is a clinical condition that from many points of view seems to be a chronic inflammatory state, and many studies confirm this observation. This influences nutritional status especially in dialysis patients. Malnutrition is related in turn to accelerated atherosclerosis thus leading to a postulated 'malnutrition, inflammation, atherosclerosis' (MIA) syndrome in which malnutrition, inflammation and atherosclerosis contribute to an elevated cardiovascular mortality rate. The present review explores this issue, first by describing epidemiological aspects of malnutrition in chronic renal failure patients and then by analysing the specific biochemical and metabolic features of these patients.

Cardio-renal cachexia syndromes (CRCS): pathophysiological foundations of a vicious pathological circle

Cardio-renal syndromes (CRS) are defined as disorders of the heart and kidney whereby acute or chronic dysfunction in one organ may induce acute or chronic dysfunction of the other. CRS have been classified into five categories, where types 2 and 4 represent respectively chronic cardio-renal and chronic reno-cardiac syndromes. In these conditions, the chronic disorder of either the heart or kidney has been shown to induce some degree of cachexia. At the same time, cachexia has been proposed as a possible mechanism contributing to the worsening of such pathological organ cross talk. Common pathogenetic mechanisms underlie body wasting in cachectic states of different chronic heart and kidney diseases. In these circumstances, a vicious circle could arise, in which cachexia associated with either heart failure or chronic kidney disease may contribute to further damage of the other organ. In chronic CRS, activation of the immune and neuroendocrine systems contributes to the genesis of cachexia, which in turn can negatively affect the heart and kidney function. In patients with cardiac sustained activation of the immune and neuroendocrine systems and oxidative stress, renal vascular resistance can increase and therefore impair renal perfusion, leading to worsening kidney function. Similarly, in renal cachexia, increased levels of pro-inflammatory cytokines can cause progressive left ventricular systolic dysfunction, myocardial cell death, endothelial dysfunction and increased myocardial fibrosis, with consequent impairment of the chronic reno-cardiac syndrome type 4. Thus, we speculate that the occurrence of different types of chronic CRS could represent a fundamental step in the genesis of cachexia, being renal and cardiac dysfunction closely related to the occurrence of systemic disorders leading to a final common pathway. Therefore, the heart and kidney and cachexia represent a triad causing a vicious circle that increases mortality and morbidity: In such circumstances, we may plausibly talk about cardio-renal cachexia syndrome. Complex interrelations may explain the transition from CRS to cachexia and from cachexia to CRS. Identification of the exact mechanisms occurring in these conditions could potentially help in preventing and treating this deadly combination.

Dietary protein intake in patients with advanced chronic kidney disease and on dialysis

Many patients with chronic kidney disease (CKD), particularly those with stage 5 CKD, have protein wasting. The degree to which increased morbidity and mortality seen in these patients is due to protein depletion rather than to the often accompanying comorbidity is not clear. High protein diets lead to the accumulation of metabolites of protein that are potentially toxic. The MDRD Study, which investigated the effects of three levels of dietary protein and phosphorus intakes and two blood pressure goals on the progression of CKD, has several limitations. Several meta-analyses have examined the effects of low protein diets (LPD) on the progression of CKD. It is possible that the lower SUN levels or lesser degree of uremic symptoms may have contributed to the positive findings of LPD in the meta-analyses of Fouque and Pedrini et al., when compared with the study of Kasiske et al. A number of published reports indicate that LPD provide adequate protein for almost all clinically stable CKD patients and do not adversely affect body composition. In general, there are no large differences in the protein intake recommended by different expert groups for a given stage of CKD.