Expert Working Group report on nutrition in adult patients with renal insufficiency (part 1 of 2)

Anaesthetic Approach to Enhanced Recovery after Surgery for Kidney Transplantation: A Narrative Review

Enhanced recovery after surgery (ERAS) protocols are designed to reduce medical complications, the length of hospital stays (LoS), and healthcare costs. ERAS is considered safe and effective for kidney transplant (KTx) surgery. KTx recipients are often frail with multiple comorbidities. As these patients follow an extensive diagnostic pathway preoperatively, the ERAS protocol can ideally be implemented at this stage. Small singular changes in a long perioperative pathway can result in significant positive outcomes. We have investigated the current evidence for an ERAS pathway related to anaesthetic considerations in renal transplant surgery for adult recipients.

Analysis of Risk Factors for Perioperative Acute Kidney Injury and Management Strategies

Acute kidney injury (AKI) is a serious clinical syndrome, and one of the common comorbidities in the perioperative period. AKI can lead to complications in surgical patients and is receiving increasing attention in clinical workup. In recent years, the analysis of perioperative risk factors has become more in-depth and detailed. In this review, the definition, diagnosis, and pathophysiological characteristics of perioperative AKI are reviewed, and the main risk factors for perioperative AKI are analyzed, including advanced age, gender, certain underlying diseases, impaired clinical status such as preoperative creatinine levels, and drugs that may impair renal function such as non-steroidal anti-inflammatory drugs (NASIDs), ACEI/ARB, and some antibiotics. Injectable contrast agents, some anesthetic drugs, specific surgical interventions, anemia, blood transfusions, hyperglycemia, and malnutrition are also highlighted. We also propose potential preventive and curative measures, including the inclusion of renal risk confirmation in the preoperative assessment, minimization of intraoperative renal toxin exposure, intraoperative management and hemodynamic optimization, remote ischemic preadaptation, glycemic control, and nutritional support. Among the management measures, we emphasize the need for careful perioperative clinical examination, timely detection and management of AKI complications, administration of dexmedetomidine for renal protection, and renal replacement therapy. We aim that this review can further increase clinicians' attention to perioperative AKI, early assessment and intervention to try to reduce the risk of AKI.

Admission kidney function is a strong predictor for the response to nutritional support in patients at nutritional risk

BACKGROUND

Patients with chronic kidney disease (CKD) are at substantial risk of malnutrition, which negatively affects clinical outcomes. We investigated the association of kidney function assessed at hospital admission and effectiveness of nutritional support in hospitalized medical patients at risk of malnutrition.

METHODS

This is a secondary analysis of an investigator-initiated, randomized-controlled, Swiss multicenter trial (EFFORT) that compared individualised nutritional support with usual hospital food on clinical outcomes. We compared effects of nutritional support on mortality in subgroups of patients stratified according to kidney function at the time of hospital admission (estimated glomerular filtration rates [eGFR] <15, 15-29, 30-59, 60-89 and ≥ 90 ml/min/1.73 m²).

RESULTS

We included 1943 of 2028 patients (96%) from the original trial with known admission creatinine levels. Admission eGFR was a strong predictor for the beneficial effects of nutritional support in regard to lowering of 30-day mortality. Patients with an eGFR <15, 15-29 and 30-59 had the strongest mortality benefit (odds ratios [95%CI] of 0.24 [0.05 to 1.25], 0.37 [0.14 to 0.95] and 0.39 [0.21 to 0.75], respectively), while patients with less severe impairment in kidney function had a less pronounced mortality benefits (p for interaction 0.001). A similar stepwise association of kidney function and response to nutritional support was found also for other secondary outcomes.

CONCLUSION

In medical inpatients at nutritional risk, admission kidney function was a strong predictor for the response to nutritional therapy. Initial kidney function may help to individualize nutritional support in the future by identification of patients with most clinical benefit.

CLINICAL TRIAL REGISTRATION

Registered under ClinicalTrials.gov Identifier no. NCT02517476.

Creatine is a Conditionally Essential Nutrient in Chronic Kidney Disease: A Hypothesis and Narrative Literature Review

To accommodate the loss of the plethora of functions of the kidneys, patients with chronic kidney disease require many dietary adjustments, including restrictions on the intake of protein, phosphorus, sodium and potassium. Plant-based foods are increasingly recommended as these foods contain smaller amounts of saturated fatty acids, protein and absorbable phosphorus than meat, generate less acid and are rich in fibers, polyunsaturated fatty acids, magnesium and potassium. Unfortunately, these dietary recommendations cannot prevent the occurrence of many symptoms, which typically include fatigue, impaired cognition, myalgia, muscle weakness, and muscle wasting. One threat coming with the recommendation of low-protein diets in patients with non-dialysis-dependent chronic kidney disease (CKD) and with high-protein diets in patients with dialysis-dependent CKD, particularly with current recommendations towards proteins coming from plant-based sources, is that of creatine deficiency. Creatine is an essential contributor in cellular energy homeostasis, yet on a daily basis 1.6–1.7% of the total creatine pool is degraded. As the average omnivorous diet cannot fully compensate for these losses, the endogenous synthesis of creatine is required for continuous replenishment. Endogenous creatine synthesis involves two enzymatic steps, of which the first step is a metabolic function of the kidney facilitated by the enzyme arginine:glycine amidinotransferase (AGAT). Recent findings strongly suggest that the capacity of renal AGAT, and thus endogenous creatine production, progressively decreases with the increasing degree of CKD, to become absent or virtually absent in dialysis patients. We hypothesize that with increasing degree of CKD, creatine coming from meat and dairy in food increasingly becomes an essential nutrient. This phenomenon will likely be present in patients with CKD stages 3, 4 and 5, but will likely be most pronouncedly present in patients with dialysis-dependent CKD, because of the combination of lowest endogenous production of creatine and unopposed losses of creatine into the dialysate. It is likely that these increased demands for dietary creatine are not sufficiently met. The result of which, may be a creatine deficiency with important contributions to the sarcopenia, fatigue, impaired quality of life, impaired cognition, and premature mortality seen in CKD.

Inadequate preoperative nutrition might be associated with acute kidney injury and greater illness severity postoperatively

OBJECTIVE

Nutrition is vital for maintaining optimal cellular and organ function, particularly in neonates who undergo cardiac surgery. Achieving nutritional goals preoperatively can be challenging because of fluid restrictions, suboptimal oral intake, and concerns for inadequate gastrointestinal circulation. We examined preoperative caloric intake and its effects on postoperative course in neonates who underwent cardiac surgery.

METHODS

We retrospectively reviewed records of neonates (younger than 30 days) who underwent congenital heart surgery requiring cardiopulmonary bypass from 2008 to 2014 at Arnold Palmer Hospital for Children. Data on multiple nutritional and postoperative variables were collected. Study outcomes included hospital length of stay, duration of mechanical ventilation, and acute kidney injury (AKI).

RESULTS

Records of 95 neonates were reviewed. Sixty-six patients (69.5%) with a median age of 5 days did not achieve preoperative caloric goal, whereas 29 patients (30.5%) with a median age of 11 days did. Of those who achieved caloric goal, 6 (20.6%) achieved it via total parental nutrition, 9 (31.1%) with a combination of total parental nutrition and enteral feeds, and 14 (48.3%) via enteral route. There was a significant difference in peak lactate (P = .002), inotropic score (P = .02), and duration of mechanical ventilation (P = .013) between those who did and did not achieve caloric goal. In multivariable analysis we found that failure to achieve caloric goal preoperatively was independently associated with stage 2 or 3 AKI (P = .04; odds ratio, 4.48; 95% confidence interval, 1.02-19.63) and younger age at the time of surgery (P < .001; odds ratio, 0.12; 95% confidence interval, 0.04-0.33).

CONCLUSIONS

Failure to achieve preoperative caloric goal might contribute to development of AKI and might be associated with greater severity of illness postoperatively.

Diet and enteral nutrition in patients with chronic kidney disease not on dialysis: a review focusing on fat, fiber and protein intake

The clinical data available on dietary requirements of patients with chronic kidney disease (CKD) not on dialysis are limited and largely inconclusive in terms of the renal, cardiovascular and nutritional outcomes achievable through dietary modifications. Restriction of protein intake during the early stages of CKD may in fact slow its progression, but at the same time this approach may also lead to protein-energy wasting, if energy intake is not adequate and properly monitored. Unfortunately, compliance to dietary recommendations is traditionally low in this patient population. A switch from saturated to mono- and polyunsaturated fats is generally recognized as advantageous for cardiac health; however, the benefits in term of renal function are largely unknown. Similarly, the association between dietary fiber intake and kidney disease is largely unknown. In fact, while there is evidence on the positive health effects of dietary fibers in the general population, nutritional guidelines for CKD lack formal recommendations concerning fiber intake. This paper reviews data and evidence from clinical trials and meta-analyses on renal and cardiovascular outcomes related to modifications in protein, fat and fiber intake. Suggestions for maintaining nutritional status through patient-oriented dietary patterns and enteral supplementation in CKD patients on conservative therapy are also presented.

An update on the pathophysiology and management of polycystic liver disease

Polycystic liver disease (PLD) is characterized by the presence of multiple cholangiocyte-derived hepatic cysts that progressively replace liver tissue. They are classified as an inherited ciliopathy /cholangiopathy as pathology exists at the level of the primary cilia of cholangiocytes. Aberrant expression of the proteins in primary cilia can impair their structures and functions, thereby promoting cystogenesis. Areas covered: This review begins by looking at the epidemiology of PLD and its natural history. It then describes the pathophysiology and corresponding potential treatment strategies for PLD. Expert commentary: Traditionally, therapies for symptomatic PLD have been limited to symptomatic management and surgical interventions. Such techniques are not completely effective, do not alter the natural history of the disease, and are linked with high rate of re-accumulation of cysts. As a result, there has been a push for drugs targeted at abnormal cellular signaling cascades to address deregulated proliferation, cell dedifferentiation, apoptosis and fluid secretion. Currently, the only available drug treatments that halt disease progression and improve quality of life in PLD patients are somatostatin analogues. Numerous preclinical studies suggest that targeting components of the signaling pathways that influence cyst development can ameliorate growth of hepatic cysts.

Vegetarian Diet in Chronic Kidney Disease-A Friend or Foe

Healthy diet is highly important, especially in patients with chronic kidney disease (CKD). Proper nutrition provides the energy to perform everyday activities, prevents infection, builds muscle, and helps to prevent kidney disease from getting worse. However, what does a proper diet mean for a CKD patient? Nutrition requirements differ depending on the level of kidney function and the presence of co-morbid conditions, including hypertension, diabetes, and cardiovascular disease. The diet of CKD patients should help to slow the rate of progression of kidney failure, reduce uremic toxicity, decrease proteinuria, maintain good nutritional status, and lower the risk of kidney disease-related secondary complications (cardiovascular disease, bone disease, and hypertension). It has been suggested that plant proteins may exert beneficial effects on blood pressure, proteinuria, and glomerular filtration rate, as well as results in milder renal tissue damage when compared to animal proteins. The National Kidney Foundation recommends vegetarianism, or part-time vegetarian diet as being beneficial to CKD patients. Their recommendations are supported by the results of studies demonstrating that a plant-based diet may hamper the development or progression of some complications of chronic kidney disease, such as heart disease, protein loss in urine, and the progression of kidney damage. However, there are sparse reports suggesting that a vegan diet is not appropriate for CKD patients and those undergoing dialysis due to the difficulty in consuming enough protein and in maintaining proper potassium and phosphorus levels. Therefore, this review will focus on the problem as to whether vegetarian diet and its modifications are suitable for chronic kidney disease patients.

Predicting clinical outcomes using phase angle as assessed by bioelectrical impedance analysis in maintenance hemodialysis patients

OBJECTIVE

Protein-energy wasting is common in patients on hemodialysis and is an independent risk factor for adverse events. The aim of this study was to retrospectively investigate whether phase angle (PA), known as a nutritional marker, can predict various clinical outcomes in patients with end-stage renal disease (ESRD) who are receiving hemodialysis.

METHODS

Using bioelectrical impedance analysis (BIA), PA was obtained every 6 mo, and patients were divided into two groups according to baseline PA: group A included patients with PA ≥4.5°, and group B included patients with PA <4.5°.

RESULTS

We followed 142 patients for a median of 29 mo (12-42 mo). We found that a decrease in PA was associated with an increased risk for death that persisted after adjusting for age, sex, and comorbidities (hazard ratio [HR], 0.56; 95% confidence interval [CI], 0.33-0.97). Cardiovascular events were not associated with PA (P = 0.685). We found that PA predicted the occurrence of infection, independent of age, sex, and comorbidities (HR, 0.65; 95% CI, 0.45-0.94). Although levels of hemoglobin did not differ between groups during the study period, patients in group B received higher doses of erythropoiesis-stimulating agents and intravenous iron than those in group A (P = 0.004 and 0.044, respectively). In longitudinal analyses, we did not find increases in PA over time in patients who had a mean dialysis adequacy ≥1.4, daily protein catabolic rate ≥1.2 g/kg, or total carbon dioxide level ≥22 mmol/L.

CONCLUSIONS

PA assessed in a simple manner using BIA provides practical information to predict clinical outcomes in ESRD patients on maintenance hemodialysis.

Assessment of Nutritional Status of Nepalese Hemodialysis Patients by Anthropometric Examinations and Modified Quantitative Subjective Global Assessment

OBJECTIVE

To assess the nutritional status of patients on maintenance hemodialysis by using modified quantitative subjective global assessment (MQSGA) and anthropometric measurements.

METHOD

We Conducted a cross sectional descriptive analytical study to assess the nutritional status of fifty four patients with chronic kidney disease undergoing maintenance hemodialysis by using MQSGA and different anthropometric and laboratory measurements like body mass index (BMI), mid-arm circumference (MAC), mid-arm muscle circumference (MAMC), triceps skin fold (TSF) and biceps skin fold (BSF), serum albumin, C-reactive protein (CRP) and lipid profile in a government tertiary hospital at Kathmandu, Nepal.

RESULTS

Based on MQSGA criteria, 66.7% of the patients suffered from mild to moderate malnutrition and 33.3% were well nourished. None of the patients were severely malnourished. CRP was positive in 56.3% patients. Serum albumin, MAC and BMI were (mean + SD) 4.0 + 0.3 mg/dl, 22 + 2.6 cm and 19.6 ± 3.2 kg/m² respectively. MQSGA showed negative correlation with MAC (r = −0.563; P = <0.001), BMI (r = −0.448; P = <0.001), MAMC (r = −0.506; P = <.0001), TSF (r = −0.483; P = <.0002), and BSF (r = −0.508; P = <0.0001). Negative correlation of MQSGA was also found with total cholesterol, triglyceride, LDL cholesterol and HDL cholesterol without any statistical significance.

CONCLUSION

Mild to moderate malnutrition was found to be present in two thirds of the patients undergoing hemodialysis. Anthropometric measurements like BMI, MAC, MAMC, BSF and TSF were negatively correlated with MQSGA. Anthropometric and laboratory assessment tools could be used for nutritional assessment as they are relatively easier, cheaper and practical markers of nutritional status.

DETECTION OF MALNUTRITION IN PATIENTS UNDERGOING MAINTENANCE HAEMODIALYSIS: A QUANTITATIVE DATA ANALYSIS ON 12 PARAMETERS

BACKGROUND

Protein-energy-malnutrition (PEM) is common in people with end stage kidney disease (ESKD) undergoing maintenance haemodialysis (MHD) and correlates strongly with mortality. To this day, there is no gold standard for detecting PEM in patients on MHD.

AIM OF STUDY

The aim of this study was to evaluate if Nutritional Risk Screening 2002 (NRS-2002), handgrip strength measurement, mid-upper arm muscle area (MUAMA), triceps skin fold measurement (TSF), serum albumin, normalised protein catabolic rate (nPCR), Kt/V and eKt/V, dry body weight, body mass index (BMI), age and time since start on MHD are relevant for assessing PEM in patients on MHD.

METHODS

The predictive value of the selected parameters on mortality and mortality or weight loss of more than 5% was assessed. Quantitative data analysis of the 12 parameters in the same patients on MHD in autumn 2009 (n = 64) and spring 2011 (n = 40) with paired statistical analysis and multivariate logistic regression analysis was performed.

RESULTS

Paired data analysis showed significant reduction of dry body weight, BMI and nPCR. Kt/Vtot did not change, eKt/v and hand grip strength measurements were significantly higher in spring 2011. No changes were detected in TSF, serum albumin, NRS-2002 and MUAMA. Serum albumin was shown to be the only predictor of death and of the combined endpoint "death or weight loss of more than 5%".

CONCLUSION

We now screen patients biannually for serum albumin, nPCR, Kt/V, handgrip measurement of the shunt-free arm, dry body weight, age and time since initiation of MHD.

Using a web-based nutrition algorithm in hemodialysis patients

OBJECTIVES

The purpose of this study was to test the ability of a newly developed nutrition algorithm on (1) clinical utility and (2) ability to capture patient outcomes.

RESEARCH DESIGN

This was a prospective observational study, using a practice based research network structure, involving renal dietitians and hemodialysis [HD] patients.

SETTING

This study took place in HD outpatient units in five different countries.

SUBJECTS

Hundred chronic HD patients were included in this study. To select subjects, dietitians screened and consented patients in their facilities until 4 patients "at nutrition risk" based on the algorithm screening tool were identified. Inclusion criteria were patients aged older than 19 years, not on hospice or equivalent, able to read the informed consent and ask questions, and receiving HD.

MAIN OUTCOME MEASURE

The ability of the algorithm screening tool is to identify patients at nutrition risk, to guide clinicians in logical renal-modified nutrition care process chains including follow-up on relevant parameters, and capture change in outcomes over 3 months. Statistics were performed using SPSS version 20.0 and significance was set at P < .05.

RESULTS

One hundred patients on HD, enrolled by 29 dietitians, were included in this analysis. The average number of out-of-range screening parameters per patient was 3.7 (standard deviation 1.5, range 1-7), and the most prevalent risk factors were elevated parathyroid hormone (PTH; 62.8%) and low serum cholesterol (56.5%). At the initial screening step, 8 of the 14 factors led to chains with nonrandom selection patterns (by χ(2) test with P < .05). In the subsequent diagnosis step, patients diagnosed within the insufficient protein group (n = 38), increased protein intake by 0.11 g/kg/day (P = .022). In patients with a diagnosis in the high PTH group, PTH decreased by a mean of 176.85 pg/mL (n = 19, P = .011) and in those with a diagnosis in the high phosphorous group, serum phosphorous decreased by a mean of 0.91 mg/dL (n = 33, P = .006). Finally, the relative likelihood of each assessment being completed after making the related diagnosis at the previous visit compared with those for whom that diagnosis was not made was assessed, including the likelihood of a patient's protein intake assessed after a diagnosis in the insufficient protein group was made (odds ratio = 4.08, P < .05).

CONCLUSIONS

This study demonstrates the clinical utility of a web-based HD-specific nutrition algorithm, including the ability to track changes in outcomes over time. There is potential for future research to use this tool and investigate the comparative impact of nutrition interventions.

Body composition monitor assessing malnutrition in the hemodialysis population independently predicts mortality

OBJECTIVE

Malnutrition is a known predictor of mortality in the general and hemodialysis populations. However, diagnosing malnutrition in dialysis patients remains problematic. Body composition monitoring (BCM) is currently used mainly for assessing overhydratation in hemodialysis patients, but it also offers the possibility of evaluating nutrition status. This study explored whether malnutrition diagnosed by BCM predicts mortality at up to 54 months follow-up in prevalent hemodialysis patients.

DESIGN

This was a retrospective epidemiology cohort study. Dialysis patients with baseline BCM measurement between 2008 and 2013 were enrolled. The observation period was up to 54 months follow-up.

SUBJECTS

A total sample consisted of 960 chronic hemodialysis participants.

INTERVENTION

All data were retrieved from medical records. Nutrition status was estimated by BCM; malnutrition was diagnosed as lean tissue index less than 10% of the normal value.

MAIN OUTCOME MEASURE

Cox regression was performed to identify whether low LTI predicted mortality in hemodialysis patients.

RESULTS

BCM-diagnosed malnutrition (hazard ratio [HR] 1.66; 95% confidence interval [CI] 1.1; 2.44), higher age (HR 1.05; 95% CI 1.03; 1.07), longer dialysis vintage (HR 1.00; 95% CI 1.00; 1.00), central venous catheter use (HR 1.96; 95% CI 1.28; 2.99), and low serum albumin (HR 0.91; 95% CI 0.87; 0.95) contributed significantly to the Cox regression model on mortality.

CONCLUSION

BCM-diagnosed malnutrition in chronic hemodialysis patients is an independent predictor of mortality at up to 54 months follow-up and is associated with a 1.66-fold higher risk of dying compared with normal nutrition status. Whether intervention (e.g., nutritional supplementation) might improve nutrition and reduce the higher risk of mortality in malnutrition patients on hemodialysis remains a challenge for future research.

Rationale and design of PICNIC study: nutritional intervention program in hospitalized patients with heart failure who are malnourished

INTRODUCTION AND OBJECTIVES

Hospitalized patients with heart failure who are malnourished present a worse prognosis than those with an adequate nutritional status. It is unknown whether a nutritional intervention can modify the prognosis of these patients. The aim of this study is to assess the efficacy of a nutritional intervention on morbidity and mortality in hospitalized patients with heart failure who are malnourished.

METHODS

PICNIC is a multicentre, randomized, controlled trial in which hospitalized patients with heart failure and malnutrition, as defined by the Mini Nutritional Assessment, are randomly assigned to conventional management of heart failure or conventional management of heart failure and an individualized nutritional intervention consisting of 3 points: optimization of diet, specific recommendations, and prescription, if deemed necessary, of nutritional supplements. A sample size of 182 patients for a maximum follow-up of 12 months has been estimated. The primary endpoint is time to death from any cause or rehospitalization because of heart failure. Analysis is by intention to treat.

CONCLUSIONS

PICNIC study will determine the prognostic impact of a nutritional intervention in hospitalized patients with heart failure who are malnourished.

Cyclic parenteral nutrition does not change the intestinal microbiota in patients with short bowel syndrome

PURPOSE: To characterize of the intestinal microbiota of patients with short bowel syndrome (SBS) admitted to the Metabolic Unit of a University Hospital. METHODS: Fecal samples were evaluated, and biochemical tests were conducted only in the case of SBS patients. The nutritional status was assessed via anthropometric measurements and evaluation of food intake by means of a food questionnaire. The pathogenic strains were detected with the aid of cultures and specific biochemical tests in aerobic medium, for determination of species belonging to the Family enterobacteriaceae. Anti-sera were applied to each isolated E. coli strain, for determination of their possible pathogenicity. Molecular methodology was employed for establishment of the intestinal bacterial microbiota profile RESULTS: A lower amount of microorganisms of the family enterobacteriaceae per gram of stool was observed in the case of patients with SBS. However, molecular analysis showed maintenance of the bacterial species ratio, which is equivalent to a healthy intestinal microbiota. CONCLUSION: Despite the massive removal of the small bowel, frequent use of antibiotics, immune system depression, presence of non-digested food in the gastrointestinal tract, and accelerated intestinal transit, the ratio between intestinal bacterial species remain similar to normality.

Exploring metabolic dysfunction in chronic kidney disease

Impaired kidney function and chronic kidney disease (CKD) leading to kidney failure and end-stage renal disease (ESRD) is a serious medical condition associated with increased morbidity, mortality, and in particular cardiovascular disease (CVD) risk. CKD is associated with multiple physiological and metabolic disturbances, including hypertension, dyslipidemia and the anorexia-cachexia syndrome which are linked to poor outcomes. Specific hormonal, inflammatory, and nutritional-metabolic factors may play key roles in CKD development and pathogenesis. These include raised proinflammatory cytokines, such as interleukin-1 and −6, tumor necrosis factor, altered hepatic acute phase proteins, including reduced albumin, increased C-reactive protein, and perturbations in normal anabolic hormone responses with reduced growth hormone-insulin-like growth factor-1 axis activity. Others include hyperactivation of the renin-angiotensin aldosterone system (RAAS), with angiotensin II and aldosterone implicated in hypertension and the promotion of insulin resistance, and subsequent pharmacological blockade shown to improve blood pressure, metabolic control and offer reno-protective effects. Abnormal adipocytokine levels including leptin and adiponectin may further promote the insulin resistant, and proinflammatory state in CKD. Ghrelin may be also implicated and controversial studies suggest activities may be reduced in human CKD, and may provide a rationale for administration of acyl-ghrelin. Poor vitamin D status has also been associated with patient outcome and CVD risk and may indicate a role for supplementation. Glucocorticoid activities traditionally known for their involvement in the pathogenesis of a number of disease states are increased and may be implicated in CKD-associated hypertension, insulin resistance, diabetes risk and cachexia, both directly and indirectly through effects on other systems including activation of the mineralcorticoid receptor. Insight into the multiple factors altered in CKD may provide useful information on disease pathogenesis, clinical assessment and treatment rationale such as potential pharmacological, nutritional and exercise therapies.

Diets and enteral supplements for improving outcomes in chronic kidney disease

Protein-energy wasting (PEW), which is manifested by low serum levels of albumin or prealbumin, sarcopenia and weight loss, is one of the strongest predictors of mortality in patients with chronic kidney disease (CKD). Although PEW might be engendered by non-nutritional conditions, such as inflammation or other comorbidities, the question of causality does not refute the effectiveness of dietary interventions and nutritional support in improving outcomes in patients with CKD. The literature indicates that PEW can be mitigated or corrected with an appropriate diet and enteral nutritional support that targets dietary protein intake. In-center meals or oral supplements provided during dialysis therapy are feasible and inexpensive interventions that might improve survival and quality of life in patients with CKD. Dietary requirements and enteral nutritional support must also be considered in patients with CKD and diabetes mellitus, in patients undergoing peritoneal dialysis, renal transplant recipients, and in children with CKD. Adjunctive pharmacological therapies, such as appetite stimulants, anabolic hormones, and antioxidative or anti-inflammatory agents, might augment dietary interventions. Intraperitoneal or intradialytic parenteral nutrition should be considered for patients with PEW whenever enteral interventions are not possible or are ineffective. Controlled trials are needed to better assess the effectiveness of in-center meals and oral supplements.

Vitamin status and needs for people with stages 3-5 chronic kidney disease

Patients with chronic kidney disease (CKD) often experience a decline in their nutrient intake starting at early stages of CKD. This reduction in intake can affect both energy-producing nutrients, such as carbohydrates, proteins, and fats, as well as vitamins, minerals, and trace elements. Knowledge of the burden and bioactivity of vitamins and their effect on the health of the patients with CKD is very incomplete. However, without sufficient data, the use of nutritional supplements to prevent inadequate intake may result in either excessive or insufficient intake of micronutrients for people with CKD. The purpose of this article is to briefly summarize the current knowledge regarding vitamin requirements for people with stages 3, 4, or 5 CKD who are not receiving dialysis.

Parenteral nutrition in patients with renal failure - Guidelines on Parenteral Nutrition, Chapter 17

Partial EN (enteral nutrition) should always be aimed for in patients with renal failure that require nutritional support. Nevertheless PN (parenteral nutrition) may be necessary in renal failure in patient groups with acute or chronic renal failure (ARF or CRF) and additional acute diseases but without extracorporeal renal replacement therapy, or in patients with ARF or CRF with additional acute diseases on extracorporeal renal replacement therapy, haemodialysis therapy (HD), peritoneal dialysis (PD) or continuous renal replacement therapy (CRRT), or in patients on HD therapy with intradialytic PN. Patients with renal failure who show marked metabolic derangements and changes in nutritional requirements require the use of specifically adapted nutrient solutions. The substrate requirements of acutely ill, non-hypercatabolic patients with CRF correspond to those of patients with ARF who are not receiving any renal replacement patients therapy (utilisation of the administered nutrients has to be monitored carefully). In ARF patients and acutely ill CRF patients on renal replacement therapy, substrate requirements depend on disease severity, type and extent/frequency of extracorporeal renal replacement therapy, nutritional status, underlying disease and complications occurring during the course of the disease. Patients under HD have a higher risk of developing malnutrition. Intradialytic PN (IDPN) should be used if causes of malnutrition cannot be eliminated and other interventions fail. IDPN should only be carried out when modifiable causes of malnutrition are excluded and enhanced oral (like i.e. additional energy drinks) or enteral supply is unsuccessful or cannot be carried out.

Bicarbonate supplementation slows progression of CKD and improves nutritional status

Bicarbonate supplementation preserves renal function in experimental chronic kidney disease (CKD), but whether the same benefit occurs in humans is unknown. Here, we randomly assigned 134 adult patients with CKD (creatinine clearance [CrCl] 15 to 30 ml/min per 1.73 m(2)) and serum bicarbonate 16 to 20 mmol/L to either supplementation with oral sodium bicarbonate or standard care for 2 yr. The primary end points were rate of CrCl decline, the proportion of patients with rapid decline of CrCl (>3 ml/min per 1.73 m(2)/yr), and ESRD (CrCl <10 ml/min). Secondary end points were dietary protein intake, normalized protein nitrogen appearance, serum albumin, and mid-arm muscle circumference. Compared with the control group, decline in CrCl was slower with bicarbonate supplementation (5.93 versus 1.88 ml/min 1.73 m(2); P < 0.0001). Patients supplemented with bicarbonate were significantly less likely to experience rapid progression (9 versus 45%; relative risk 0.15; 95% confidence interval 0.06 to 0.40; P < 0.0001). Similarly, fewer patients supplemented with bicarbonate developed ESRD (6.5 versus 33%; relative risk 0.13; 95% confidence interval 0.04 to 0.40; P < 0.001). Nutritional parameters improved significantly with bicarbonate supplementation, which was well tolerated. This study demonstrates that bicarbonate supplementation slows the rate of progression of renal failure to ESRD and improves nutritional status among patients with CKD.

Positive effects of protein restriction in patients with chronic kidney disease

OBJECTIVES

The potential benefit or harm of low-protein diets (LPDs) for patients with chronic kidney disease has been debated. This study sought to investigate the effects of treatment with LPDs on nutritional markers, morbidity, and survival during subsequent dialysis. A second objective was to evaluate the effect of LPDs on renal function and the start of dialysis.

DESIGN

This was a retrospective study of medical records.

SETTING

The setting was an outpatient nephrology and dialysis clinic.

PATIENTS

One-hundred twenty-two renal patients were recruited from the central dialysis registry of one clinic. The patients had been followed by a nephrologist for > or =6 months before dialysis. Sixty-one patients were treated with LPDs, and an equal number of control patients not treated with LPDs were matched for sex, age, dialysis modality, diabetes, and start of dialysis.

MAIN OUTCOME MEASURES

Main outcome measures included weight and weight change, serum albumin, glomerular filtration rate, morbidity, and mortality.

RESULTS

There was less mean weight loss in the LPD group the year before dialysis (0.14 kg/month, compared with the control group at 0.36 kg/month, P < .05). The level of serum albumin was higher in the LPD group at the start of dialysis (P < .01). The mean rate of progression during the 6 months before dialysis was lower in the LPD group (4.1 mL/min/year) than in the control group (13.4 mL/min/year) (P < .001). The LPD group had fewer days of hospitalization at the start of dialysis than the control group (8.2 vs 15.4 days, respectively, P < .01). There was no difference in mortality between groups 1, 2, or 5 years after starting dialysis.

CONCLUSIONS

Low-protein diets can reduce patient morbidity, preserve renal function, relieve uremic symptoms and improve nutritional status. The results suggest that LPDs can postpone the start of dialysis for 6 months, and entail substantial cost-savings. Low-protein diets should be used more generally in the renal community.

Eleven reasons to control the protein intake of patients with chronic kidney disease

For many years patients with chronic kidney disease have been advised to control the protein content of their diet. This advice has been given on the basis of a number of reported metabolic effects of lowering protein intake, such as lowering serum urea nitrogen levels, improving phosphocalcic metabolism and insulin resistance and, more recently, ameliorating proteinuria (independent of antiproteinuric medications). The effects on the progression of kidney disease, although spectacular in experimental studies, have been less convincing in humans. It is possible that flawed design of clinical trials is responsible for this discrepancy. In this Review, we comment on experimental findings that indicate that limiting protein intake protects the kidney and ameliorates uremic symptoms, outline how the body adapts to a reduction in protein intake, and describe the metabolic benefits to the patient. We then review the evidence from randomized controlled trials and meta-analyses that pertains to the effects of low-protein diets in adults with chronic kidney disease.

ESPEN Guidelines on Enteral Nutrition: Adult Renal Failure

Enteral nutrition (EN) by means of oral nutritional supplements (ONS) and tube feeding (TF) offers the possibility of increasing or ensuring nutrient intake in cases where normal food intake is inadequate. These guidelines are intended to give evidence-based recommendations for the use of ONS and TF in nephrology patients. They were developed by an interdisciplinary expert group in accordance with officially accepted standards and are based on all relevant publications since 1985. They were discussed and accepted in a consensus conference. Because of the nutritional impact of renal diseases, EN is widely used in nephrology practice. Patients with acute renal failure (ARF) and critical illness are characterized by a highly catabolic state and need depurative techniques inducing massive nutrient loss. EN by TF is the preferred route for nutritional support in these patients. EN by means of ONS is the preferred way of refeeding for depleted conservatively treated chronic renal failure patients and dialysis patients. Undernutrition is an independent factor of survival in dialysis patients. ONS was shown to improve nutritional status in this setting. An increase in survival has been recently reported when nutritional status was improved by ONS.

Application of branched-chain amino acids in human pathological states: renal failure

During renal failure, abnormalities of BCAA and branched-chain keto acid (BCKA) metabolism are due to both the lack of renal contribution to amino acid metabolism and the impact of renal failure and acidosis on whole-body nitrogen metabolism. Abnormal BCAA and BCKA metabolism result in BCAA depletion as reflected by low plasma BCAAs and cellular valine. BCAA metabolic disturbances can alter tissue activities, particularly brain function, and nutritional status. In dialysis patients, BCAA oral supplementation can induce an improvement of appetite and nutritional status. During chronic renal failure, the aims of nutritional interventions are to minimize uremic toxicity, avoid malnutrition and delay progression of kidney disease. BCAA and BCKA supplements have been proposed to decrease further protein intake while maintaining satisfactory nutritional status. In this setting, BCAAs or BCKAs have not been administrated solely but in association with other essential AA or keto analogs. Therefore, the proper effects of BCAAs and/or BCKAs have not been studied separately. Protein restriction together with keto acids and/or essential AAs has been reported to improve insulin sensitivity and hyperparathyroidism and to be compatible with a preservation of nutritional status. Nonetheless, a careful monitoring of protein-calorie intake and nutritional status is needed. A recent meta-analysis concluded that reducing protein intake in patients with chronic renal failure reduces the occurrence of renal death by approximately 40% as compared with larger or unrestricted protein intake. The additional effect of essential amino acids and keto acids on retardation of progression of renal failure has not been demonstrated.

Influence of low protein diet on nonthyroidal illness syndrome in chronic renal failure

Renal failure causes alterations in thyroid hormone metabolism known as nonthyroidal illness syndrome. In the present study we have examined the effect of a low protein diet (LPD) on circulating levels of hormones of the pituitary-thyroid axis, and tumor necrosis factor alpha (TNF-alpha) in patients with chronic renal failure. Seventeen subjects with conservatively treated chronic renal failure (estimated creatinine clearance 39.5+/-11.1 mL/min) were studied before and after 8 wk of dietary intervention (0.6 g/kg of ideal body mass protein, 30% of calories derived from fat, 62% of calories derived from carbohydrates, and 10 mg/kg of phosphorus). Body fat and fat-free mass remained unchanged. Urea and TNF-alpha serum concentrations significantly decreased, whereas T3 and total and free T4 serum concentrations increased significantly. Triiodothyronine level after treatment correlated negatively with baseline urea level. Changes in T3, T4, and fT4 serum concentrations as well as calculated peripheral deiodinase activity correlated negatively with their baseline values. Alterations in TNF-alpha correlated positively with protein intake, whereas changes in T4 and T4/TSH were inversely related to vegetal protein intake. In conclusion, low protein, low phosphorus diet, which is often prescribed to patients with moderate impairment of renal function, exerts a beneficial effect on low T3 syndrome coexisting with renal failure. The effect of low protein diet on the pituitary-thyroid axis is dependent on the degree of renal functional impairment and LPD-induced decrease in TNF-alpha may also contribute to the observed effects of dietary treatment.

Body Composition in Diabetic Subjects with Chronic Kidney Disease: Interest of Bio-Impedance Analysis, and Anthropometry

BACKGROUND/AIMS

Lean body mass (LBM) is reduced in uremia, but this has not been reported in diabetic nephropathy.

SUBJECTS AND METHODS

We compared predicted % LBM to DEXA measurements in 10 non-diabetic uremic, 10 non-uremic diabetic and 10 uremic diabetic subjects matched for age, gender and BMI. We also measured % LBM by anthropometry, bio-impedance analysis (BIA) and compared them with DEXA in 49 diabetic subjects with a wide range of renal failure. The results were compared and a Bland & Altman procedure was performed. Associations between glomerular filtration rate (GFR) and % LBM were tested.

RESULTS

In matched groups, predicted % LBM values were overestimated in non-diabetic uremic subjects, and underestimated in non-uremic diabetic subjects. In uremic diabetic subjects, the error was intermediary. As compared to DEXA (% LBM: 69.0 +/- 7.1%), measurement of % LBM by anthropometry (71.4 +/- 8.0%, p < 0.05) and BIA (67.2 +/- 7.6%, p < 0.05) were biased in the 49 diabetic subjects. The mean of anthropometric and BIA (Ant+BIA) were similar to DEXA results (69.3 +/- 6.8%, p = 0.64), with best correlation coefficients and Bland & Altman plots. GFR was correlated to % LBM assessed by DEXA, BIA and Ant+BIA.

CONCLUSION

In diabetic subjects with chronic kidney disease, LBM should be measured, rather than predicted. A good evaluation is possible, even without DEXA.

Resting energy expenditure in uremic, diabetic, and uremic diabetic subjects

We compared Harris and Benedict [H & B; Harris, J. A., & Benedict, F. G. (1919). A biometric study of basal metabolism in man. Washington, DC: Carnegie Institution of Washington. p. 279.] predicted resting energy expenditure (REE) to values measured by indirect calorimetry in normal, uremic, diabetic, and uremic diabetic subjects. Predicted REE were overestimated (+9.2%, P<.005) in uremic subjects, and underestimated (-8.5%, P<.0001) in diabetic subjects. Uremic diabetic subjects were submitted to the opposite influences of diabetes and uremia on REE. Differences in body composition (lower fat-free mass in uremia and higher fat-free mass in diabetes) played a major role in these influences. In uremic diabetic subjects, predicted REE seemed well fitted to measured REE (biases <2%), but they were less correlated, and limits of agreement between predicted and measured REE were large. Although their mean REE seems normal, prediction by the H&B equation leads to important individual errors in uremic diabetic subjects: direct measurement of energy expenditure by indirect calorimetry may be helpful to precise the adequate energy content of a diet for these subjects.

Metabolism and clinical interest of serum transthyretin (prealbumin) in dialysis patients

Chronic renal failure is responsible for an increase in serum concentrations of transthyretin. Elevated serum transthyretin during renal insufficiency is secondary to the lack of retinol-binding protein degradation in renal tubules and to the subsequent increase in the fraction of transthyretin bound to retinol-binding protein. In both hemodialysis and peritoneal dialysis patients, serum transthyretin was demonstrated to be a reliable marker of nutritional status, exhibiting significant relationships with energy and protein intakes as well as with fat stores and lean body mass. Serum transthyretin levels less than 300 mg/l were shown to be associated with an increased risk of morbidity and mortality in dialysis patients. The predictive value of transthyretin was shown to be independent of serum albumin. Regular measurements of both serum albumin and transthyretin make it possible to detect patients whose prognosis is compromised by malnutrition and in whom an active nutritional therapy must be undertaken. Simultaneous measurements of inflammatory markers such as serum C-reactive protein are required to evaluate the role of inflammation in serum albumin and transthyretin variations. These low-cost protein parameters should be incorporated in the regular assessment of dialysis patients and measured every 1 to 3 months.

The National Kidney Foundation K/DOQI clinical practice guidelines for dietary protein intake for chronic dialysis patients

This paper discusses two of the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (K/DOQI) clinical practice guidelines for nutrition in chronic renal failure. These are the guidelines that recommend a dietary protein intake of 1.2 g protein/kg body weight/day for clinically stable maintenance hemodialysis (MHD) patients (Guideline 15) and 1.2 to 1.3 g protein/kg/day for clinically stable chronic peritoneal dialysis (CPD) patients (Guideline 16). These recommended protein intakes are greater than the usually ingested protein intakes of MHD and CPD patients and are also greater than the recommended protein intakes for healthy, nonpregnant, nonlactating adults. The possible mechanisms that engender these increased protein needs include (1) the substantial quantity of amino acids, peptides, and proteins removed by the dialysis procedure and (2) the protein catabolic or antianabolic state caused by the uremic milieu, the inflammatory state, the oxidative and carbonyl stress, and the bioincompatible dialysis materials to which MHD and CPD patients are exposed. There are a number of nitrogen balance studies that have been performed to identify the dietary protein needs of MHD and CPD patents. The results of this research as well as some of the methodological limitations of these studies are reviewed. The concepts of the average dietary protein intake required to maintain protein balance in MHD or CPD patients and the safe protein intake that will maintain protein balance in virtually all MHD and CPD patients are discussed.