Pathophysiology of protein-energy wasting in chronic renal failure

Changes in dietary protein intake has no effect on serum cystatin C levels independent of the glomerular filtration rate

Cystatin C is being considered as a replacement for serum creatinine in the estimation of the glomerular filtration rate (GFR); however, its plasma levels might be affected by factors other than the GFR, such as protein intake. We performed a post hoc analysis of the data in the Modification of Diet in Renal Disease study, in which we compared serum creatinine and cystatin C levels in 741 patients with available estimates of protein intake at baseline prior to their randomization to diets containing various amounts of protein, and at 2 years of follow-up in 426 of these patients in whom a cystatin C measurement was available. The 503 patients in study A (GFR 25-55 ml/min per 1.73 m(2)) had been assigned a low (0.58 g/kg per day) or a usual (1.3 g/kg per day) protein intake, and the 238 participants in study B (GFR 13-24 ml/min per 1.73 m(2)) were assigned a very low (0.28 g/kg per day) or the low protein intake. In either study group, lowering the dietary protein intake reduced the change in creatinine, but did not have a significant change in cystatin C. Thus, in patients with moderate-to-severe chronic kidney disease, serum cystatin C unlike serum creatinine was not affected by dietary protein intake independent of changes in GFR. Hence, cystatin C may allow more accurate estimates of GFR than creatinine for patients with reduced protein intake. Further study of other non-GFR determinants of cystatin C is needed before the widespread adoption.

Unintentional weight loss is an independent predictor of mortality in a hemodialysis population

OBJECTIVE

This study investigated common components of classification of nutrition screening risk in the prediction of clinical end-points (mortality and morbidity) in hemodialysis patients over a 3-year period (2005 to 2008).

DESIGN

This was a retrospective cohort study.

SETTING

This study was conducted at a Hemodialysis centre.

PARTICIPANTS

The study included patients on maintenance hemodialysis in June 2005.

INTERVENTION

Assessment of nutrition risk was carried out using components of Protein-Energy Wasting criteria.

MAIN OUTCOME MEASURE

Clinical outcome at the 3-year follow-up (June 2008) was measured as mortality and morbidity (as unplanned hospital admissions). Risk of mortality was investigated independent of comorbidities, age, gender, ethnicity, and dialysis vintage using Cox proportional hazards model.

RESULTS

A total of 217 patients met the inclusion criteria (143 male [66%]; age, 60.5 ± 15.6 years). Patients who lost ≥5% body weight in the 6 months before the study commenced, had a 3-fold (Hazard Ratio = 3.0; 95% confidence interval: 1.2 to 7.5) independent greater risk of death (P = .02). Low serum albumin (<38 g/L) resulted in higher morbidity and mortality; however, this was not statistically significant when adjusted for confounders. Body mass index was only available in 64% (138 of 217) of the cohort at baseline, and was not related to clinical outcome at the 3-year follow-up.

CONCLUSION

Unintentional weight loss is independently predictive of clinical outcome in this cohort of dialysis patients. It is recommended that nutrition screening tools include weight loss as a key component in classification of risk and for prioritizing patient care.

High-calorie diet partially ameliorates dysregulation of intrarenal lipid metabolism in remnant kidney

Chronic renal failure (CRF) is associated with malnutrition and renal tissue accumulation of lipids, which can contribute to progression of renal disease. This study was designed to explore the effect of a high-calorie diet on pathways involved in lipid metabolism in the remnant kidney of rats with CRF. 5/6 nephrectomized rats were randomized to receive a regular diet (3.0 kcal/g) or a high-calorie diet (4.5 kcal/g) for 12 weeks. Renal lipid contents and abundance of molecules involved in cholesterol and fatty acid metabolism were studied. The CRF group consuming a regular diet exhibited growth retardation; azotemia; proteinuria; glomerulosclerosis; tubulointerstitial injury; heavy lipid accumulation in the remnant kidney; up-regulation of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), ATP-binding cassette transporter-1 (ABCA1), liver X receptor (LXR) α/β, carbohydrate-responsive element binding protein (ChREBP) and acyl-CoA carboxylase (ACC); and down-regulation of peroxisome proliferator-activated receptor-α (PPAR-α), carnitine palmitoyltransferase-1 (CPT1) and liver-type fatty acid binding protein (L-FABP). The high-calorie diet restored growth; reduced the severity of tubulointerstitial injury, proteinuria and azotemia; partially lowered renal tissue lipid contents; attenuated the up-regulation of mediators of lipid influx (LOX-1), lipid efflux (LXR-α/β and ABCA1) and fatty acid biosynthesis (ChREBP and ACC); and reversed the down-regulation of factors involved in fatty acid oxidation (PPAR-α, CPT1 and L-FABP). In conclusion, a high-calorie diet restores growth, improves renal function and structure, and lowers lipid burden in the remnant kidney. The latter is associated with and most likely due to reduction in lipid influx and enhancement of fatty acid oxidation.

Resistance exercise and nutrition to counteract muscle wasting

Loss of muscle mass is an unfavourable consequence of aging and many chronic diseases. The debilitating effects of muscle loss include declines in physical function and quality of life and increases in morbidity and mortality. Loss of muscle mass is the result of a decrease in muscle protein synthesis, an increase in muscle protein degradation, or a combination of both. Much research on muscle wasting has tended to focus on preventing muscle protein breakdown, and less attention has been paid to providing adequate stimulation to increase muscle protein synthesis. In this review, we present evidence to suggest that interventions aimed at increasing muscle protein synthesis represent the most effective countermeasure for preventing, delaying, or reversing the loss of skeletal muscle mass experienced in various muscle wasting conditions. Based on results from acute and chronic studies in humans in a wide variety of wasting conditions, we propose that resistance exercise training combined with appropriately timed protein (likely leucine-rich) ingestion represents a highly effective means to promote muscle hypertrophy, and may represent a highly effective treatment strategy to counteract the muscle wasting tassociated with aging and chronic disease.

Ghrelin and obestatin levels in end-stage renal disease

Malnutrition is fairly common in end-stage renal disease (ESRD) patients, persistent lack of appetite being a major symptom. Ghrelin and obestatin are two hormones that are involved in appetite and energy homeostasis. The present study examined ghrelin and obestatin levels in 24 ESRD patients undergoing haemodialysis and 24 age-matched healthy controls. Serum and saliva ghrelin and obestatin levels in the ESRD patients were significantly higher compared with controls, while saliva ghrelin and obestatin levels in all study participants were significantly higher than serum levels. Saliva ghrelin correlated with serum ghrelin and saliva obestatin correlated with serum obestatin in all study participants, although there was no correlation between ghrelin and obestatin levels. In conclusion, the results suggest that the kidneys may have a role in the metabolism and/or clearance of obestatin, as they do for ghrelin. Further studies are needed to determine if elevated levels of these hormones in ESRD patients contribute to the malnutrition that is common in these patients.

Determinants of resting energy expenditure in hemodialysis patients, and comparison with healthy subjects

OBJECTIVE

This study evaluated the factors that affect the resting energy expenditure (REE) and nutritional status of hemodialysis patients, and to assess any differences with healthy subjects.

DESIGN

This was an observational case-control study.

SETTING

This study took place at the Hemodialysis Units of the Laikon General Hospital and 401 General Military Hospital (Athens, Greece).

PATIENTS

Twenty-five patients undergoing hemodialysis and 23 controls were recruited. Controls were healthy volunteers with no history of diseases or medication use. Patients with active infectious or inflammatory disease were excluded.

INTERVENTION

We measured REE using indirect calorimetry. Body composition as measured by Bioelectrical Impedance Analysis (BIA), anthropometry, and biochemical parameters were assessed in both groups.

MAIN OUTCOME MEASURE

Adjusted or unadjusted for muscle mass, REE was compared between the two groups. Multiple linear regression analysis was used to study independent determinants of REE.

RESULTS

Patients had no clinical signs of malnutrition. Resting energy expenditure was not different between the two groups, but REE adjusted for muscle mass was significanlty higher in hemodialysis patients. There were no differences in body composition, with the exception of muscle mass. Patients had lower muscle mass than controls, as determined by duration of disease. The only significant determinant of REE was muscle mass.

CONCLUSION

Patients had a higher REE adjusted for muscle mass than did controls, implying that they might be at a catabolic stage, and at risk of malnutrition. These findings indicate the need for determining body composition and for nutritional assessment and support in hemodialysis patients, even without indications of malnutrition.

Correlation of Dietary Intakes and Biochemical Determinates of Nutrition in Hemodialysis Patients

OBJECTIVE

The purpose of this study was to determine the effect of dietary intakes on nutritional indicators of patients on hemodialysis.

METHOD

This study was carried out at the hemodialysis unit at the Ministry of Health, Ankara Hospital, from 2003-2004. Sixty-seven patients on regular hemodialysis were enrolled in the study. Nutritional status was assessed by biochemical parameters (urea, uric acid, creatinine, Na, K, Cl, Ca, P, alkaline phosphatase, SGOT, SGPT, cholesterol, total protein, albumin, hemoglobin, hematocrit) and anthropometric measurements (height, dry weight, body mass index), and dietary intakes were calculated.

RESULTS

In this study, the mean age of the patients was 45.3 +/- 13.49, and the duration of hemodialysis was 4.9 +/- 3.64 year. Dialysis time was 12.4 +/- 2.7 h/week. The ratio of individuals with BMI of 20 kg/m2 or below this value was 19.4%. Blood hemoglobin and hematocrit levels were below than the recommended level. Mean serum urea (148.0 +/- 27.76 mg/dL) and creatinine (8.8 +/- 2.13 mg/dL) were found to be high, while a significant negative correlation was found between blood urea level and dietary fat (p < 0.01, r = -0.31). A significant positive correlation was found between vitamin B1, vitamin B6, folate, potassium, iron, and magnesium; between uric acid and vitamin D; between blood creatinine level and dietary vitamin B1, vitamin B6, folate, vitamin C, potassium, iron, magnesium; between blood potassium level and dietary vitamin C only; and between blood cholesterol level and dietary vitamin D only (p < 0.01).

Nutrition aspects in children receiving maintenance hemodialysis: impact on outcome

Children with end-stage renal disease (ESRD) have rates of mortality estimated to be 30-times higher than expected for age compared with those of healthy children. Physical manifestations of under-nutrition, such as body mass index (BMI) and low height standard deviation score (SDS), have been associated with increased risk of mortality. Traditional measures, such as height, weight and serum albumin concentration, may not be accurate indicators to assess the nutritional status of children receiving maintenance hemodialysis. Normalized protein catabolic rate (nPCR) has emerged as a better marker of nutritional status of such children. Meeting the special nutritional needs of these children often requires nutritional supplementation, by either the enteral or the parenteral route. Recently, in children receiving maintenance hemodialysis who are malnourished, intradialytic parenteral nutrition (IDPN) has been utilized as a means to provide additional protein and calories. This article is a state-of-the-art review of malnutrition in children receiving maintenance hemodialysis, with special focus on outcome, nPCR and IDPN.

Malnutrition-inflammation-atherosclerosis syndrome in Chronic Kidney disease

Chronic kidney disease is becoming a major health problem globally and in India an alarming number of about 8 million people are suffering from this disease. Patients undergoing hemodialysis have a high prevalence of protein-energy malnutrition and inflammation. As these two conditions often occur concomitantly in hemodialysis patients, they have been referred together as 'malnutrition-inflammation-atherosclerosis syndrome' to emphasize the important association with atherosclerotic cardiovascular disease. The three factors related to the pathophysiology in these patients are dialysis related nutrient loss, increased protein catabolism and hypoalbuminemia. Inflammation in Chronic Kidney disease is the most important factor in the genesis of several complications in renal disease. Pro-inflammatory cytokines like IL-1 and TNF-alpha play a major role in the onset of metabolic alterations in Chronic Kidney disease patients. Atherosclerosis is a very frequent complication in uremia due to the coexistence of hypertension, hyperhomocysteinemia, inflammation, malnutrition and increased oxidative stress, generation of advanced glycation end products, advanced oxidation protein products, hyperlipidemia and altered structural and functional ability of HDL. LDL-cholesterol, apolipoprotein (A), apolipoprotein (B), and Lp(a) are also associated with atherosclerosis. Studies have now provided enormous data to enable the evaluation of the severity of malnutrition-inflammation-atherosclerosis syndrome as well as effective monitoring of these patients.

Consequences of low plasma histidine in chronic kidney disease patients: associations with inflammation, oxidative stress, and mortality

BACKGROUND

Histidine is considered as an antiinflammatory and antioxidant factor. Histidine deficiency may contribute to an impaired nutritional state in patients with chronic kidney disease (CKD).

OBJECTIVE

We aimed to investigate the consequences of plasma histidine deficiency in CKD patients.

DESIGN

CKD patients (n = 325; 203 M) with a median age of 54 y (range: 19-70 y) were evaluated shortly before the beginning of renal replacement therapy. The median glomerular filtration rate was 6.4 mL/min (range: 0.8-14.5 mL/min). Nutritional status was assessed by subjective global assessment. Survival was followed for up to 60 mo; 101 patients died.

RESULTS

Plasma histidine concentrations were significantly lower in CKD patients with history of cardiovascular disease, presence of plaques, protein-energy wasting, and inflammation. Plasma histidine was negatively associated with age, C-reactive protein, interleukin-6, leukocytes, thrombocytes, fibrinogen, hepatocyte growth factor, adhesion molecules, insulin-like growth factor-1, and 8-hydroxy-2'-deoxyguanosine and was positively associated with handgrip strength, hemoglobin, S-albumin and fetuin-A. A multivariate regression analysis showed that histidine concentrations were independently associated with hepatocyte growth factor, hemoglobin, and fetuin-A. In unadjusted analysis, a low histidine concentration was associated with all-cause mortality (log rank chi-square test = 8.9; P = 0.002). After adjustment for age, sex, cardiovascular disease, inflammation, diabetes mellitus, serum S-albumin, and amino acid supplementation, the association between low histidine and mortality remained significant (hazard ratio: 1.55; 95% CI: 1.02, 2.40; P < 0.05).

CONCLUSION

Low plasma concentrations of histidine are associated with protein-energy wasting, inflammation, oxidative stress, and greater mortality in CKD patients.

Dialysis adequacy and nutritional status of hemodialysis patients

To characterize the nutritional status of renal failure patients and its relationship with hemodialysis adequacy measured by Kt/V, a study was carried out with a population of 44 adult patients with renal failure and mean age 51+/-15 years. Anthropometric data, such as dry weight, height, arm circumference, triceps skinfold thickness, mid-arm muscle circumference, and body mass index were assessed, and biochemical tests were conducted for urea, potassium, creatinine, serum albumin, and phosphorus levels, in addition to hemogram and quarterly urea reduction rate average (Kt/V). In order to evaluate calorie intake, a dietary questionnaire on habitual daily food ingestion was administered, taking into consideration the hemodialysis date. The patients were divided into 2 separate groups for the statistical analysis, with 50% of the patients in each group: A (Kt/V<1.2) and B (Kt/V>1.2). The data were tabulated as mean and standard deviation, with differences tested by Student's t test. The correlations between variables were established by the coefficient p of Pearson. Most of the patients (43%) were considered eutrophic, based on the BMI, and presented inadequate calorie intake, corresponding to 88.5+/-24% (30.8 kcal/kg actual weight) of the total energy required and adequate protein intake, reaching 109.9+/-40% of the recommended daily allowance (1.24 g/kg of actual weight). There was a correlation of Kt/V with anthropometric parameters such as body mass index, arm circumference, and mid-arm muscle circumference. The biochemical parameters related to dialysis adequacy were albumin, ferritin, and urea (predialysis). Well-dialyzed patients presented better levels of serum albumin. There was an influence of gender and age on correlations of the analyzed variables. Female and younger patients presented better dialysis adequacy. The dialysis adequacy was related to the nutritional status and influenced by the protein intake and body composition. Gender and age had an important influence in the dialysis adequacy, as men presented lower dialysis adequacy and younger adults presented better dialysis adequacy. Further research is necessary to understand better how to facilitate effective and efficient techniques for the nutritional status assessment of hemodialysis patients.

Role of adipose tissue in determining muscle mass in patients with chronic kidney disease

OBJECTIVE

Malnutrition is a powerful predictor of mortality in chronic kidney disease (CKD). However, its etiology is unclear. We hypothesized that the adipocyte-derived proteins leptin and adiponectin, inflammation (as measured by C-reactive protein, CRP), and insulin resistance (as measured by homeostasis model assessment, HOMA), implicated in the malnutrition-inflammation complex syndrome commonly seen in maintenance dialysis patients, would be associated with the loss of muscle mass in earlier stages of CKD. Arm muscle area was used as an indicator of muscle mass.

PATIENTS AND SETTING

The Modification of Diet in Renal Disease Study cohort of people with CKD stages 3 and 4 was used for analysis (N = 780).

MAIN OUTCOME MEASURES

Regression models were carried out to examine the relationships of leptin, adiponectin, CRP, and HOMA with arm muscle area (the main study outcome).

RESULTS

Arm muscle area was 39 +/- 15 cm(2) (mean +/- SD), and adiponectin levels were 13 +/- 7 microg/mL. Median and interquartile range (IQR) concentrations were: 9.0 (13.6) ng/mL for leptin, 2.3 (4.9) mg/L for CRP, and 2.4 (2.0) for HOMA. Higher leptin (beta coefficient and 95% confidence interval, -6.9 [-8.7 to -5.1], P < .001) and higher CRP (beta coefficient and 95% confidence interval, -2.7 [-3.9 to -1.4], P < .001) were associated with lower arm muscle area. There was a trend toward lower arm muscle area with higher adiponectin (P = .07), but no association with HOMA (P = .80).

CONCLUSION

Leptin and CRP were associated with lower muscle mass in subjects with CKD at stages 3 and 4. Further studies are needed to understand the mechanisms underlying these associations, and to develop targeted interventions for this patient population.

Nutrient intake during peritoneal dialysis at the Prince of Wales Hospital in Hong Kong

BACKGROUND

Individuals undergoing peritoneal dialysis are at increased risk of developing cardiac disease and malnutrition.

STUDY DESIGN

A cross-sectional survey.

SETTINGS AND PARTICIPANTS

249 Chinese continuous ambulatory peritoneal dialysis (CAPD) patients were recruited from the Prince of Wales Hospital in Hong Kong. Another 249 age- and sex-matched controls were recruited from an archive of 1,010 individuals with known food frequency questionnaire (FFQ) data.

OBJECTIVE

To compare the dietary intake pattern of CAPD patients with controls and evaluate its association with background cardiac disease.

OUTCOMES AND MEASUREMENTS

Intake of different nutrients was estimated by using a 7-day FFQ.

RESULTS

Intake of all nutrients was lower in CAPD patients than controls, with resulting lower overall energy intake. Nutrient intake was decreased further in CAPD patients with background cardiac disease, which corresponded to worse nutritional status. Controlling for age, male sex, body weight, diabetes mellitus, dialysis therapy duration, residual renal function, peritoneal dialysis urea clearance, and Charlson Comorbidity Index score, background cardiac disease was associated independently with less intake of energy and most macronutrients and micronutrients. However, the association between background cardiac disease and energy and most nutrient intake was decreased or even lost when additional adjustment was made for C-reactive protein and serum albumin levels.

LIMITATIONS

An FFQ is limited in that nutrient quantitation is not exact and may be underestimated as a result of underreporting by patients. CAPD patients were compared with a control group without cardiovascular disease ascertainment that did not include subjects with diabetes.

CONCLUSIONS

Chinese CAPD patients had significantly lower nutrient intake than age- and sex-matched controls. The association between cardiac disease and lower dietary macronutrient and micronutrient intake in CAPD patients was mediated in part through systemic inflammation, which also was associated with more malnutrition. More attention should be focused on improving the intake pattern of Chinese CAPD patients.

Hepatitis C inflection in dialysis patients: a link to poor clinical outcome?

Among the 350,000 maintenance dialysis patients in the USA, the mortality rate is high (20-23% per year) as is the prevalence of hepatitis C virus (HCV) infection (5-15%). An additional same number of dialysis patients in the USA may be infected with HCV but have undetectable HCV antibodies. Almost half of all deaths in dialysis patients, including HCV-infected patients, are due to cardiovascular disease. Since over two-thirds of dialysis patients die within 5 years of initiating dialysis and because markers of malnutrition-inflammation complex syndrome (MICS), rather than traditional cardiovascular risk factors, are among the strongest predictors of early death in these patients, the impact of HCV infection on nutritional status and inflammation may be a main cause of poor survival in this population. Based on data from our cross-sectional and limited longitudinal studies, we hypothesize that HCV infection confounds the association between MICS and clinical outcomes in dialysis patients and, by doing so, leads to higher short-term cardiovascular events and death. Understanding the natural history of HCV and its association with inflammation, nutrition and outcomes in dialysis patients may lead to testing more effective anti-HCV management strategies in this and other similar patient populations, providing benefits not only for HCV infection but the detrimental consequences associated with this infection. In this article, we review the link between the HCV infection and mortality in dialysis patients and compare HCV antibody to molecular methods to detect HCV infection in these individuals.

Epidemiology of dialysis patients and heart failure patients

The epidemiology of maintenance dialysis patients and heart failure patients has striking similarities. Both groups have a high prevalence of comorbid conditions, a high hospitalization rate, a low self-reported quality of life, and an excessively high mortality risk, mostly because of cardiovascular causes. Observational studies in both dialysis and heart failure patients have indicated the lack of a significant association between the traditional cardiovascular risk factors and mortality, or the existence of a paradoxic or reverse association, in that obesity, hypercholesterolemia, and hypertension appear to confer survival advantages. The time discrepancy between the 2 sets of risk factors, that is, overnutrition (long-term killer) versus undernutrition (short-term killer) may explain the overwhelming role of malnutrition, inflammation, and cachexia in causing the reverse epidemiology, which may exist in more than 20 million Americans. We have reviewed the opposing views about the concept of reverse epidemiology in dialysis and heart failure patients, the recent Die Deutsche Diabetes Dialyze study findings, and the possible role of racial disparities. Contradictory findings on hyperhomocysteinemia in dialysis patients are reviewed in greater details as a possible example of publication bias. Additional findings related to intravenous iron and serum ferritin, calcium, and leptin levels in dialysis patients may enhance our understanding of the new paradigm. The association between obesity and increased death risk in kidney transplanted patients is reviewed as an example of the reversal of reverse epidemiology. Studying the epidemiology of dialysis patients as the archetypical population with such paradoxic associations may lead to the development of population-specific guidelines and treatment strategies beyond the current Framingham cardiovascular risk factor paradigm.

Transcriptional Levels of Growth Factors in Skeletal Muscle of Maintenance Hemodialysis Patients

This study was performed to assess the mRNA levels in skeletal muscle of maintenance hemodialysis (MHD) patients. Fifty-one sedentary MHD patients and 21 sedentary normal adults of similar age, gender distribution, and racial/ethnic mix as the patients were examined. The subjects had needle muscle biopsy to measure mRNA levels. They were assessed in right vastus lateralis muscle for insulinlike growth factor I (IGF-IEa and IGF-IEc), IGF-II, the IGF-I receptor, the IGF-II receptor, and myostatin. mRNA was measured by real-time polymerase chain reaction amplification of reverse transcribed cDNA. The results showed that in the MHD patients, as compared with the normal control patients, skeletal muscle mRNA levels for IGF-IEa, IGF-II, and the IGF-I receptor were significantly reduced, whereas mRNA for IGF-IEc, IGF-II receptor, and myostatin were not different than normal. We conclude that sedentary MHD patients show reductions in mRNA levels in the right vastus lateralis muscle for certain growth factor proteins, notably IGF-IEa, IGF-II, and the IGF-I receptor. These abnormalities may contribute to the sarcopenia and impaired endurance capacity, strength, and physical performance that occur in MHD patients.

Nutritional Status in Hemodialysis Patients: Options for On-Line Convective Treatment

Although hemodialysis (HD) has improved the life expectancy of patients with end-stage renal disease (ESRD), uremic patients continue to experience high morbidity and mortality. Two of the most important risk factors for morbidity and mortality are protein-energy malnutrition (PEM) and inflammation. The causes for PEM in ESRD are numerous. The use of materials for dialysis, especially of the dialyzer membrane, is reported as one of the recognized causes for chronic inflammation in hemodialysis. We performed a 6-month prospective study examining the influence of on-line predilution hemodiafiltration on the inflammatory and nutritional status in a population of male hemodialysis patients using ultrapure dialysis fluid and polyamide dialyzers. We evaluated serum C-reactive protein, albumin, and transferrin and some nutritional parameters such as body mass index (BMI), phase angle (phi), fatty mass (FM), and free fatty mass (FFM) using bioelectrical impedance (BIA). Results showed significant amelioration of BMI and the re-equilibrium of the acute phase protein after on-line predilution hemodiafiltration. These results support the hypothesis that on-line predilution hemodiafiltration, as convective extracorporeal treatment, may be used to treat malnourished hemodialysis patients and to prevent malnutrition in the ESRD patient at risk for malnutrition.

Chronic Obstructive Pulmonary Disease, inflammation and co-morbidity--a common inflammatory phenotype?

Chronic Obstructive Pulmonary Disease (COPD) is and will remain a major cause of morbidity and mortality worldwide. The severity of airflow obstruction is known to relate to overall health status and mortality. However, even allowing for common aetiological factors, a link has been identified between COPD and other systemic diseases such as cardiovascular disease, diabetes and osteoporosis.

COPD is known to be an inflammatory condition and neutrophil elastase has long been considered a significant mediator of the disease. Pro-inflammatory cytokines, in particular TNF-α (Tumour Necrosis Factor alpha), may be the driving force behind the disease process. However, the roles of inflammation and these pro-inflammatory cytokines may extend beyond the lungs and play a part in the systemic effects of the disease and associated co-morbidities. This article describes the mechanisms involved and proposes a common inflammatory TNF-α phenotype that may, in part, account for the associations.

Menu Suggestion: An Effective Way to Improve Dietary Compliance in Peritoneal Dialysis Patients

OBJECTIVE

Poor compliance with the dietary prescriptions is quite common in dialysis patients. We believe that most of the noncompliance is caused by the patient's poor understanding of the dietary prescription. Therefore, in the present study, we tried to investigate the role of menu suggestion in improving the patient's compliance with the dietary prescription.

DESIGN AND SETTING

A longitudinal cohort study conducted at an outpatient dialysis clinic.

PATIENTS

Seventy clinically stable patients on peritoneal dialysis were included in this prospective study during April 1, 2004, to November 31, 2004, in a single center. Patients who had significant cognitive impairment and thus did not understand the food contents during the training course were not eligible for enrollment.

INTERVENTION

All the patients were randomly assigned to 1 of 2 groups. Group 1 patients received the traditional patient education method. Group 2 patients additionally received individualized menu suggestions based on their food preferences and education on how to exchange the foods at equivalent amounts according to the exchange list.

MAIN OUTCOME MEASURES

At present, there are no clear optimal dietary protein intake levels for peritoneal dialysis patients. Our experience is that a dietary protein intake level of 0.8 to 1.2 g/kg/d can maintain our patients in a good nutritional status. Thereafter, in this study we prescribed the dietary protein intake level at 0.8 to 1.2 g/kg/d and defined compliance as meeting this target protein intake level.

RESULTS

There were 35 patients in each group. The compliance was 22.9% in group 1 and 57.1% in group 2 (P < .05).

CONCLUSIONS

Our study suggests that menu suggestion may be an effective way of improving the compliance with the diet in peritoneal dialysis patients. It improves the patient's understanding of the dietary prescription.

Nutritional Status and Food Insecurity in Hemodialysis Patients

OBJECTIVE

The purpose of this study was to determine whether a relationship exists between nutrition status and food security of patients on hemodialysis (HD).

DESIGN

A descriptive correlation study.

SETTING

This study consisted of HD patients undergoing treatment at three northeast Louisiana dialysis centers.

PATIENTS

Ninety-eight HD patients participated in the study. The mean age of subjects was 59.1 +/- 14.2 years. The sample was 44% white and 56% black; 49% male and 51% female.

RESULTS

Multiple linear regression and chi2 analysis were used to assess relationships between demographics and food insecurity scores and Subjective Global Assessment scores. Race significantly predicted food insecurity (beta = 0.248; P = .019), with black patients being more food insecure than white subjects. A significant positive relationship was found between the level of education and Subjective Global Assessment scores (beta = 0.222; P = .037). In this sample, 16.3% of the subjects were found to be food insecure, and 64.3% of the patients were mildly to moderately malnourished, whereas another 13.3% were severely malnourished.

CONCLUSIONS

Future research in this area should include food security questions related to the ability to obtain foods for health. Renal health care professionals should assess patients for possible food insecurity so that appropriate interventions can be implemented.

Intradialytic Parenteral Nutrition Treatment and Biochemical Marker Assessment for Malnutrition in Adolescent Maintenance Hemodialysis Patients

Protein-energy malnutrition (PEM) is a significant cause of morbidity and mortality for patients receiving maintenance hemodialysis. Minimal study has evaluated therapeutic options for and biochemical marker assessment of pediatric patient PEM. In 2001, we expanded the indications for intradialytic parenteral nutrition (IDPN) treatment of PEM to all maintenance hemodialysis patients, regardless of etiology, who had a >10% weight loss and were at less than the 90th percentile of ideal body weight. Nine patients received thrice weekly IDPN from 3 to 22 months with minimal side effects. Six patients had weight and body mass index increase, 1 patient stopped losing weight, and 2 patients continued to lose weight during the initial 5 months of IDPN therapy. Cohort subanalysis showed that all patients with organic PEM responded to IDPN therapy, whereas patients with psychosocial causes of PEM did not. The normalized protein catabolic rate increased significantly for patients whose condition responded to IDPN therapy, whereas serum albumin did not change. The current study suggests that IDPN is effective treatment of organic causes of PEM in pediatric patients receiving maintenance hemodialysis and that normalized protein catabolic rate may be superior to serum albumin as a marker of nutrition status. The observation that IDPN was not sufficient to reverse PEM in patients with psychosocial PEM causes should direct caregivers to address the relevant underlying causes as well as to provide intensive nutrition therapy.

A dramatic reduction of normalized protein catabolic rate occurs late in the course of progressive renal insufficiency

BACKGROUND

Spontaneous reduction in dietary protein intake is a recognized feature of severe renal failure, and previous studies have suggested that this may occur at an early stage of renal functional decline.

METHODS

We examined the effects of progressive renal insufficiency on the normalized protein catabolic rate (nPCR) in 1282 patients (mean age 55.8+/-15.5 years; 60.4% male) over a 7 year period. All values of nPCR (n = 5082) obtained before commencement of dialysis were included. A total of 361 (28.2%) patients later developed end-stage renal failure and were started on dialysis.

RESULTS

Cross-sectional analysis showed nPCR being significantly less at lower creatinine clearance. Mean nPCR was 1.17+/-0.31 at a clearance >50, 1.04+/-0.27 at 25-50, 0.93+/-0.21 at 10-25 and 0.74+/-0.18 at <10 ml/min. Mean nPCR in each clearance group was different from that in all other groups (P<0.001 in all cases). When nPCR was studied longitudinally in relation to time of initiation of dialysis, the fall in nPCR only became significant in the 3 months preceding initiation. Curve fitting suggested a two-phase exponential association between nPCR and renal function, a gentle decline of nPCR in mild and moderate renal failure culminating in a dramatic decline when CrCl reached 15 ml/min and weekly Kt/V(urea) 2.5. nPCR at dialysis initiation predicted survival on dialysis even when corrected for age, diabetes and non-renal co-morbid load. However, it was no longer significant when residual renal function was included in the model. The group initiating dialysis with a normal nPCR maintained this throughout the first 3 years on dialysis whilst the group initiating with a low nPCR, though improving initially, continued to have significantly lower nPCR levels throughout follow-up than their normal nPCR counterparts.

CONCLUSION

A significant reduction of nPCR occurs late in progressive renal insufficiency and may predict the need for dialysis initiation. nPCR levels <0.8 at initiation predict future low nPCR levels and mortality on dialysis. The correlation between nPCR and CrCl in early renal insufficiency may be partly artefactual.

Reverse epidemiology: a spurious hypothesis or a hardcore reality?

In maintenance hemodialysis (MHD) patients, associations between demographic, clinical and laboratory values and mortality, including cardiovascular death, are significantly different and, in some cases, in the opposite direction of those derived from the general population. This phenomenon, termed 'reverse epidemiology', is not limited to MHD patients but is also observed in populations that encompass an estimated 20 million Americans including those with an advanced age, heart failure, malignancies, and AIDS. A significant portion of this reversal may be due to the overwhelming effect of the malnutrition-inflammation complex syndrome (MICS). Since two thirds of MHD patients die within 5 years of initiation of dialysis treatment, traditional cardiovascular risk factors such as obesity, hypercholesterolemia and hypertension cannot exert a long-term deleterious impact, and instead, their short-term beneficial effects on MICS provides a survival advantage. In order to improve survival and quality of life in MHD patients, extrapolated ideal norms derived from the general population should be substituted with novel norms obtained from outcome-oriented epidemiologic analyses while accounting for the differential effect of MICS in different case-mix subgroups.

C-reactive protein is a significant predictor of decrease in fat mass in hemodialysis patients

Malnutrition and inflammation are common in hemodialysis patients, and are usually closely associated. We examined annual body fat mass changes, a possible nutritional parameter, in maintenance hemodialysis patients, and investigated the factors affecting such changes. Body fat mass of 454 hemodialysis patients (61+/-11 years, 269 males and 185 females) was measured twice by dual energy X-ray absorptiometry (DEXA), with a 12-month interval between measurements. In a total of 65 patients with hemodialysis duration of less than 1 year at the first measurement, fat mass at the second measurement had increased significantly over the course of a year (P<0.0001). In contrast, in a total of 389 patients with hemodialysis duration of more than 1 year at the first measurement, fat mass at the second measurement significantly decreased (P<0.005). In the 389 patients, significant negative correlations were seen between fat mass changes and CRP (r=-0.165, P<0.005). In a multiple regression analysis, CRP was a significant factor (beta=-0.163, P<0.005) affecting fat mass changes, independent of other confounding clinical factors (R(2)=0.127, P<0.001). These results show that body fat mass of long-term hemodialysis patients decreases after an initial increase in the first to second years of hemodialysis. In hemodialysis patients, fat mass change appears to be a parameter indicative of nutritional changes. Chronic inflammation, represented by higher CRP levels, is a significant factor affecting decrease in fat mass, and is related to poorer nutritional status.

Strong Association Between Volume Status and Nutritional Status in Peritoneal Dialysis Patients

BACKGROUND

Malnutrition is a strong predictor of mortality in maintenance peritoneal dialysis (PD) patients. Various factors have been identified to contribute to the development of malnutrition. The present study tried to investigate the possible role of fluid overload in the development of malnutrition.

METHODS

Twenty-eight PD patients were included in this study. Fluid status was evaluated by means of repeated bioimpedance analysis, and nutritional status was assessed by means of handgrip strength and subjective global assessment. All patients were followed up closely for 9 months. Based on changes in bioimpedance analysis data, patients were divided into group A (with continuous and steadily improved fluid status; n = 18) and group B (with consistent fluid overload; n = 10).

RESULTS

There were no differences in sex, age, and height between the 2 groups. In group A, patients' extracellular water (ECW) volume decreased significantly during follow-up, whereas intracellular water (ICW) volume increased significantly (both P < 0.001). In group B, ECW volume increased significantly, whereas ICW volume increased at an early stage and then decreased. The ratio of ECW to total-body water decreased significantly in group A, but increased significantly in group B. Along with the improvement in fluid status, nutritional status in group A also improved significantly (the prevalence of malnutrition decreased from 66.7% to 11.1%; P < 0.01). However, in group B, nutritional status deteriorated significantly (handgrip strength decreased from 238.33 +/- 88.93 to 216.1 +/- 86.19 N; P < 0.05; and the prevalence of malnutrition increased from 40% to 50%).

CONCLUSION

Our data suggest there is a strong association between fluid status and nutritional status. Improved fluid status is associated with improvement in nutritional status, whereas deterioration in fluid status is associated with the development of malnutrition.

Assessment of nutritional status in hemodialysis patients using patient-generated subjective global assessment

OBJECTIVE

To evaluate the scored Patient-Generated Subjective Global Assessment (PG-SGA) as a nutrition assessment tool in hemodialysis patients.

DESIGN

A cross-sectional observational study assessing the nutritional status of hemodialysis patients.

SETTING

Private tertiary Australian hospital.

SUBJECTS

Sixty patients, ages 63.9 +/- 16.2 years.

INTERVENTION

Scored PG-SGA questionnaire, comparison of PG-SGA score > or =9 with subjective global assessment (SGA), albumin, corrected arm muscle area, and triceps skinfold.

RESULTS

According to SGA, 80% of patients were well nourished and 20% of patients were malnourished. Patients classified as well nourished (SGA-A) attained a significantly lower median PG-SGA score compared with those rated as moderately malnourished or at risk of malnutrition (SGA-B). A PG-SGA score > or =9 had a sensitivity of 83% and a specificity of 92% at predicting SGA classification. There were significant correlations between the PG-SGA score and serum albumin, PG-SGA score, and percentage weight loss over the past 6 months. There was no association between PG-SGA score and body mass index or anthropometric measurements.

CONCLUSION

The scored PG-SGA is an easy-to-use nutrition assessment tool that allows quick identification of malnutrition in hemodialysis patients.

L-carnitine infusions may suppress serum C-reactive protein and improve nutritional status in maintenance hemodialysis patients

Scattered reports indicate that L-carnitine may suppress proinflammatory cytokines in sick individuals without renal disease and may improve protein synthesis or nitrogen balance either in patients without renal disease or in maintenance hemodialysis (MHD) or chronic peritoneal dialysis patients. We conducted an experimental study in MHD patients to evaluate the effects of L-carnitine treatment on inflammatory and protein-energy nutritional status. MHD patients were assigned to receive intravenous injections of L-carnitine 20 mg/kg (n = 48) or placebo (n = 65) thrice weekly at the end of each hemodialysis treatment for 6 months. The carnitine-treated group showed a statistically significant decrease in serum C-reactive protein and increase in serum albumin and transferrin, blood hemoglobin, and body mass index. Conversely, in the placebo-treated group, a significant decrease was reported for serum albumin, serum transferrin, and body mass index, whereas the other considered measures did not change significantly. These preliminary findings suggest that in MHD patients, L-carnitine therapy may suppress inflammation, particularly among those patients with C-reactive protein > or =3 mg/dL, and may improve protein-energy nutritional status.

Avaliação nutricional de pacientes em hemodiálise

OBJETIVO: O objetivo deste estudo foi o de avaliar o estado nutricional e a ingestão de energia e de nutrientes de uma população em hemodiálise no Hospital das Clínicas, Universidade Federal de Pernambuco. MÉTODOS: De um total de 47 pacientes em hemodiálise de manutenção, 37 indivíduos (18 homens e 19 mulheres, idade 50,4 ± 16,3 anos) foram selecionados. O índice de massa corporal foi utilizado para a classificação do estado nutricional e a dieta foi investigada por meio do método do diário alimentar de 4 dias. RESULTADOS: Os resultados evidenciaram um predomínio de indivíduos eutróficos (62,2%) e igual prevalência de baixo peso e excesso de peso (18,9% de pacientes em cada caso). Com relação à dieta, os achados desta pesquisa revelaram um adequado consumo energético-protéico. De uma forma geral, a ingestão média diária de nutrientes foi considerada adequada, exceto pelo cálcio e pela vitamina A, que apresentaram <50,0% e <70,0% da ingestão diária recomendada, respectivamente. CONCLUSÃO: Esses resultados indicam que se deve dar atenção cuidadosa às diferenças regionais e nacionais que influenciam o estado nutricional e a ingestão dietética de pacientes em hemodiálise.

Role of carnitine in modulating acute-phase protein synthesis in hemodialysis patients

Increased serum levels of C-reactive protein (CRP) in uremic and dialysis patients are associated with low serum prealbumin and albumin concentrations and increased mortality and greater risk of cardiovascular disease. Proinflammatory cytokines may cause malnutrition by increasing protein catabolism. Many studies have shown that L-carnitine supplementation leads to improvements in several conditions seen in uremic patients, including cardiac complications, impaired exercise and functional capacities, muscle symptoms, increased symptomatic intradialytic hypotension, and erythropoietin-resistant anemia. L-carnitine therapy may either suppress the inflammatory response or act independently on both inflammation and appetite and/or anabolic processes. Moreover, L-carnitine may suppress proinflammatory cytokines in sick individuals without renal disease and may improve protein synthesis or nitrogen balance in patients without renal disease and in hemodialysis and peritoneal dialysis patients. In a pilot study, we provided preliminary evidence that treatment with L-carnitine, 20 mg/kg 3 times weekly at the end of each hemodialysis treatment, was associated with a reduction in serum CRP levels and improvement in anabolic status. The improvement or normalization of serum concentrations of serum CRP also was correlated with increased serum concentrations of albumin, transferrin, and blood hemoglobin. The possibility that some or all of these changes may have been caused by improved nutritional intake cannot be ruled out. Further randomized clinical trials will be necessary to confirm the role of L-carnitine as a modulator of inflammatory protein synthesis in hemodialysis patients.

Prevalence of malnutrition in Nigerians with chronic renal failure

In developed countries, malnutrition is common in patients with chronic renal failure (CRF) and has adverse effects on patient morbidity and mortality. The prevalence of malnutrition before the initiation of dialysis is poorly characterized in CRF patients in developing countries. We studied the prevalence of malnutrition among Nigerians with CRF before commencement of dialysis. Body mass index (BMI) and serum protein levels were measured in 74 dialysis naïve Nigerians with CRF and 48 controls. Patients with nephrotic syndrome, steroid use and failure of organs other than the kidneys were excluded. The mean BMI was significantly lower in the patients compared to the controls (22.4 +/- 14.9 kg/M2 Vs. 25.2 +/- 2.7 kg/M2; p = 0.0001). Low BMI (less than 20 Kg/M2) was present in 16 (21.6%) of the patients compared with one of the controls. The mean serum total protein and albumin were also significantly lower in the patients compared to controls (61.9 +/- 14.4 g/L Vs. 73.8 +/- 6.8 g/L; p < 0.0001, and 31.5 +/- 9.3 g/L Vs. 39.6 +/- 4.4 g/L; p < 0.0001 respectively). Protein malnutrition (serum albumin < 29 g/L) was present in 32 (43.2%) of patients with CRF and one (2.1%) of the control subjects. Malnutrition is common in Nigerian CRF patients before the commencement of dialysis. In these patients, emphasis should be placed on prevention and/or correction of malnutrition because of its documented adverse effects on the outcomes of maintenance dialysis.

Malnutrition-inflammation complex syndrome in dialysis patients: causes and consequences

Protein-energy malnutrition (PEM) and inflammation are common and usually concurrent in maintenance dialysis patients. Many factors that appear to lead to these 2 conditions overlap, as do assessment tools and such criteria for detecting them as hypoalbuminemia. Both these conditions are related to poor dialysis outcome. Low appetite and a hypercatabolic state are among common features. PEM in dialysis patients has been suggested to be secondary to inflammation; however, the evidence is not conclusive, and an equicausal status or even opposite causal direction is possible. Hence, malnutrition-inflammation complex syndrome (MICS) is an appropriate term. Possible causes of MICS include comorbid illnesses, oxidative and carbonyl stress, nutrient loss through dialysis, anorexia and low nutrient intake, uremic toxins, decreased clearance of inflammatory cytokines, volume overload, and dialysis-related factors. MICS is believed to be the main cause of erythropoietin hyporesponsiveness, high rate of cardiovascular atherosclerotic disease, decreased quality of life, and increased mortality and hospitalization in dialysis patients. Because MICS leads to a low body mass index, hypocholesterolemia, hypocreatininemia, and hypohomocysteinemia, a "reverse epidemiology" of cardiovascular risks can occur in dialysis patients. Therefore, obesity, hypercholesterolemia, and increased blood levels of creatinine and homocysteine appear to be protective and paradoxically associated with a better outcome. There is no consensus about how to determine the degree of severity of MICS or how to manage it. Several diagnostic tools and treatment modalities are discussed. Successful management of MICS may ameliorate the cardiovascular epidemic and poor outcome in dialysis patients. Clinical trials focusing on MICS and its possible causes and consequences are urgently required to improve poor clinical outcome in dialysis patients.

Nutritional profile of patients with chronic renal failure

OBJECTIVE

A substantial number of patients with end-stage chronic renal failure (CRF) on dialysis have an inflammatory state that can be detected by elevation in serum levels of C-reactive protein (CRP). Hypoalbuminemia, which occurs in this population and always has been associated with malnutrition, seems to be a consequence of this inflammatory state. Data focusing on patients before dialysis treatment are lacking.

DESIGN

Cross-sectional observational study.

SETTING

Outpatients from the Nephrology Division of the University Hospital.

PATIENTS

We investigated nutritional status and serum CRP in 27 patients (13 women) with advanced CRF on the occasion of their first visit.

METHODS

Nutritional status was evaluated by anthropometric and serum measurements. Energy and protein intake were evaluated using a 24-hour recall questionnaire.

RESULTS

Data are reported as mean +/- SD. Glomerular filtration rate was 18 +/- 5 mL/min. Anthropometric measurements showed normal body mass index in 75% of the patients, whereas the remaining patients were overweight; fat store was depleted in 60% of the patients. Serum albumin was 4.4 +/- 0.5 mg/dL and CRP was 0.47 +/- 0.63 mg/dL. Protein ingestion was 1.04 +/- 0.24 g/kg/d, and energy intake was 23.57 +/- 7.8 kcal/kg/d.

CONCLUSION

Patients with advanced CRF without specific treatment, evaluated for the first time, showed fat store depletion. This alteration was not associated with inflammation or with visceral protein loss, but with low energy intake. These results support the idea that this population should be followed up by specialists from the early stage of CRF to prevent malnutrition.

Chronic consumption of a moderately low protein diet does not alter hematopoietic processes in young adult mice

The current studies examined whether hematopoiesis in the bone marrow and T-cell development in the thymus were attenuated in young adult A/J mice fed a moderately low protein diet (MPD, 50 g protein/kg) for 15 wk compared with mice fed a control protein diet (CPD, 180 g protein/kg). Flow cytometric analyses using antibodies against CD31 and Ly-6C as well as CD4 and CD8 were performed to identify stem, mixed progenitor, erythroid, lymphoid, granuloid and monocytic compartments in the bone marrow and four thymocyte subsets, respectively. Chronic restriction of young adult mice to MPD neither decreased the cellularity nor altered the distribution of subpopulations in either primary tissue. Subsequently, a new set of mice were provided with CPD and a low protein diet (LPD, 25 g protein/kg). After 5 wk, body and thymus weights in LPD group were reduced 26 and 30%, respectively, which was accompanied by a 505% increase in serum corticosterone. Surprisingly, LPD did not alter the number or distribution of cells in the bone marrow and the percentages of thymocyte subsets, supporting the findings from the MPD group. We conclude that chronic consumption of a marginal protein diet by young adult mice does not disrupt hematopoietic processes.

Longitudinal study of nutritional status, body composition, and physical function in hemodialysis patients

BACKGROUND

Cross-sectional studies have shown an association between the duration (y) of dialysis and nutritional status, providing evidence of wasting.

OBJECTIVE

The aim was to determine the extent, pace, determinants, and optimal methods of assessing wasting in patients undergoing hemodialysis.

DESIGN

Laboratory variables, body composition, and physical activity, function, and performance were tested 4 times over 1 y in 54 hemodialysis patients. Changes in repeated measures were evaluated, with adjustment for baseline differences by age, sex, race, diabetes status, and dialysis vintage (ie, time since initiation of dialysis).

RESULTS

No significant changes in body weight, fat mass, lean body mass, or laboratory variables were observed. Phase angle, a bioelectrical impedance analysis-derived variable related to body cell mass, decreased significantly (linear estimate: -0.043 degrees /mo, or approximately 0.5 degrees/y; P = 0.001). Physical activity measured by accelerometry declined 3.4%/mo (P = 0.01). The Maximum Activity Score of the Human Activity Profile (HAP) also declined significantly (linear estimate: -0.50/mo, or approximately 6 points/y; P = 0.025). Higher interleukin 1beta (IL-1beta) concentrations were associated with a narrower phase angle (P = 0.004) and with a more rapid decline in phase angle with time (time x IL-1beta interaction, P = 0.01); similar effects of IL-1beta on physical activity were observed. Dietary protein and energy intakes were associated with changes in the HAP.

CONCLUSIONS

Evidence of adverse changes in body composition and physical activity, function, and performance and of a modest influence of inflammation and dietary intake on these changes was observed in this cohort. Tools such as bioelectrical impedance analysis, accelerometry, and the HAP may be required to identify subtle changes.

Important factors other than dialysis adequacy associated with inadequate dietary protein and energy intakes in patients receiving maintenance peritoneal dialysis

BACKGROUND

Anorexia that results in inadequate nutrient intake is considered one of the most important causes of malnutrition in dialysis patients.

OBJECTIVE

The objective was to determine factors other than dialysis adequacy that are associated with inadequate protein and energy intakes in patients receiving continuous ambulatory peritoneal dialysis.

DESIGN

Dietary protein and energy intakes were assessed with a food-frequency questionnaire in 266 patients, and factors other than dialysis adequacy that are potentially associated with reductions in energy and protein intakes were examined.

RESULTS

Only 39% of the patients had protein intakes > or = 1.2 g x kg(- 1) x d(- 1), and 26% had energy intakes > or = 126 kJ x kg(- 1) x d(- 1). Other than having a greater total urea clearance and glomerular filtration rate, patients with protein intakes > or = 1.2, as opposed to < 1.2, g x kg(- 1) x d(- 1) had lower high-sensitive C-reactive protein concentrations and fewer complications with volume overload (29% compared with 46%; P = 0.006). Patients with energy intakes > or = 126, as opposed to < 126, kJ x kg(- 1) x d(- 1) were younger, had lower high-sensitive C-reactive protein concentrations, and had a lower prevalence of diabetes (P = 0.006), atherosclerotic vascular disease (P = 0.020), and history of volume overload (P = 0.013). Multiple regression analysis showed that other than increasing age, diabetes, and total urea clearance, having a history of volume overload was independently associated with a 0.22-g x kg(- 1) x d(- 1)decrease in protein (P = 0.001) and a 13.07-kJ x kg(- 1) x d(- 1) decrease in energy intake (P = 0.006).

CONCLUSION

An important yet unrecognized association was observed between a history of volume overload and dietary intake in peritoneal dialysis patients.

Nutritional problems associated with end-stage renal disease in the developing world

Protein-energy malnutrition is a major problem in dialysis patients. There is increased morbidity and mortality in dialysis patients with malnutrition. There are very few published studies on nutritional parameters and adequacy of dialysis from the developing world and especially from Africa. There was a significant improvement in neuromuscular function and nutrition in 22 hemodialysis patients in Egypt with optimization of dialysis dose and nutritional status. In a study of 82 continuous ambulatory peritoneal dialysis (CAPD) patients in Durban, South Africa, there was a reduction in the number of hospital admissions in adequately dialyzed patients (achieving Kt/V of >2.1). In another study of 84 CAPD patients from the same center, 76.2% of patients were assessed as being malnourished, with loss of appetite being an important etiological factor. Strategies to optimize dialysis dose, together with services of a renal dietician, will assist in improving the nutrition of patients with chronic renal failure.

A malnutrition-inflammation score is correlated with morbidity and mortality in maintenance hemodialysis patients

Malnutrition inflammation complex syndrome (MICS) occurs commonly in maintenance hemodialysis (MHD) patients and may correlate with increased morbidity and mortality. An optimal, comprehensive, quantitative system that assesses MICS could be a useful measure of clinical status and may be a predictor of outcome in MHD patients. We therefore attempted to develop and validate such an instrument, comparing it with conventional measures of nutrition and inflammation, as well as prospective hospitalization and mortality. Using components of the conventional Subjective Global Assessment (SGA), a semiquantitative scale with three severity levels, the Dialysis Malnutrition Score (DMS), a fully quantitative scoring system consisting of 7 SGA components, with total score ranging between 7 (normal) and 35 (severely malnourished), was recently developed. To improve the DMS, we added three new elements to the 7 DMS components: body mass index, serum albumin level, and total iron-binding capacity to represent serum transferrin level. This new comprehensive Malnutrition-Inflammation Score (MIS) has 10 components, each with four levels of severity, from 0 (normal) to 3 (very severe). The sum of all 10 MIS components ranges from 0 to 30, denoting increasing degree of severity. These scores were compared with anthropometric measurements, near-infrared-measured body fat percentage, laboratory measures that included serum C-reactive protein (CRP), and 12-month prospective hospitalization and mortality rates. Eighty-three outpatients (44 men, 39 women; age, 59 +/- 15 years) on MHD therapy for at least 3 months (43 +/- 33 months) were evaluated at the beginning of this study and followed up for 1 year. The SGA, DMS, and MIS were assessed simultaneously on all patients by a trained physician. Case-mix-adjusted correlation coefficients for the MIS were significant for hospitalization days (r = 0.45; P < 0.001) and frequency of hospitalization (r = 0.46; P < 0.001). Compared with the SGA and DMS, most pertinent correlation coefficients were stronger with the MIS. The MIS, but not the SGA or DMS, correlated significantly with creatinine level, hematocrit, and CRP level. During the 12-month follow-up, 9 patients died and 6 patients left the cohort. The Cox proportional hazard-calculated relative risk for death for each 10-unit increase in the MIS was 10.43 (95% confidence interval, 2.28 to 47.64; P = 0.002). The MIS was superior to its components or different subversions for predicting mortality. The MIS appears to be a comprehensive scoring system with significant associations with prospective hospitalization and mortality, as well as measures of nutrition, inflammation, and anemia in MHD patients. The MIS may be superior to the conventional SGA and the DMS, as well as to individual laboratory values, as a predictor of dialysis outcome and an indicator of MICS.

Elevated plasma F2-isoprostanes in patients on long-term hemodialysis

BACKGROUND

End-stage renal disease (ESRD) patients on long-term hemodialysis (HD) may be under increased oxidative stress, caused by either HD or renal failure. Plasma F2-isoprostanes have been established as an important indicator of in vivo oxidative stress.

METHODS

Plasma esterified F2-isoprostanes were measured in 25 HD patients and 23 controls with normal renal function, employing gas chromatography-mass spectrometry with negative chemical ionization (GC-MS-NCI). C-reactive protein (CRP) was determined concurrently in patients and controls by enzyme-linked immunosorbent assay (ELISA). alpha-Tocopherol, retinol, albumin and creatinine were also determined.

RESULTS

The average total esterified F2-isoprostanes in the ESRD patients was 1.62 +/- 0.73 vs. 0.27 +/- 0.10 ng/mL in controls (P < 0.001), with no overlap between patients and controls. Plasma F2-isoprostanes in diabetic ESRD patients were similar to F2-isoprostanes in patients with other causes for renal failure. In a subset of 10 of these ESRD patients evaluated eight months after the initial measurement, plasma-esterified F2-isoprostanes were not altered by an individual dialysis session. Average plasma CRP values were also higher in HD patients (P < 0.02), but some patients had CRP values that were similar to controls. In the HD patients, total plasma F2-isoprostanes and plasma CRP were correlated (r = 0.48, P = 0.015). Plasma alpha-tocopherol did not differ between patients and controls, but plasma retinol was higher in patients (3.15 +/- 1.71 micromol/L) than in controls (1.97 +/- 0.51 micromol/L, P < 0.05).

CONCLUSIONS

These results are consistent with the hypothesis that oxidative stress in ESRD patients contributes to increased values of esterified plasma F2-isoprostanes, with concurrent increases in plasma CRP levels in some patients. Impaired clearance of esterified F2-isoprostanes may contribute to the elevated levels in renal failure. Plasma esterified F2-isoprostanes may be a useful indicator to evaluate effectiveness of interventions to decrease oxidative stress and associated inflammation.

Leptin is a negative acute phase protein in chronic hemodialysis patients

BACKGROUND

Hypoalbuminemia strongly predicts death in hemodialysis patients and results from both inflammation and malnutrition. One potential link between malnutrition and inflammation is appetite suppression triggered by inflammation. Leptin is secreted by adipose tissue and suppresses appetite, and it is also a positive acute phase protein in the rat. Factored for body weight, leptin is known to be increased in hemodialysis patients, but its relationship to inflammation is unknown.

METHODS

We examined the relationship between spontaneously occurring activation of the acute phase response and leptin levels in 29 chronic hemodialysis patients. Serum samples were obtained three times weekly for six weeks and then monthly from 29 chronic hemodialysis patients, and the levels of the positive acute phase proteins [C-reactive protein (CRP), alpha1-acid glycoprotein (alpha1 AG), serum amyloid A, ceruloplasmin] and the negative acute phase proteins (albumin and transferrin) as well as leptin and interleukin-6 (IL-6) were measured.

RESULTS

Positive and negative acute phase proteins were evaluated at the maximum CRP (mean, 9.42 +/- 1.14 mg/dL) and minimum values (mean, 0.41 +/- 0.09 mg/dL). When CRP was elevated, leptin levels were significantly reduced, as were the negative acute phase proteins albumin and transferrin. Serum amyloid A, ceruloplasmin, alpha1 acid glycoprotein, and IL-6 were all significantly increased at the maximum CRP level, compatible with general activation of the acute phase response. The change in leptin correlated negatively with the change in CRP (R = 0.437, P = 0.018), as did changes in albumin (R = 0.620, P < 0.001).

CONCLUSIONS

Leptin is not increased as a consequence of inflammation in hemodialysis patients, but behaves as a negative rather than as a positive acute phase protein. Inflammation is unlikely to reduce appetite in dialysis patients through a leptin-mediated mechanism.

National kidney foundation K/DOQI clinical practice guidelines for nutrition in chronic renal failure

The National Kidney Foundation Kidney Disease Outcomes Quality Initiative Clinical Practice Guidelines for Nutrition in Chronic Renal Failure was recently published in the American Journal of Kidney Diseases. This publication provides 27 clinical practice guidelines for adults and 10 clinical practice guidelines for children. The adult guidelines focus primarily on patients undergoing maintenance dialysis therapy, although there are several clinical practice guidelines on nutritional issues for patients with advanced chronic renal failure (CRF) not undergoing dialysis therapy. The pediatric guidelines focus entirely on children undergoing maintenance dialysis treatment. The present article discusses a number of the more prominent clinical practice guidelines for the adults. Among these is the recommendation that the protein-energy nutritional status in these patients should be assessed by a panel of measures rather than by any single measure. Also, non-dialyzed patients with advanced CRF (ie, glomerular filtration rate <25 mL/min) and those undergoing maintenance hemodialysis or chronic peritoneal dialysis should be prescribed a dietary energy intake of 35 kcal/kg/day for patients who are <60 years of age and 30 kcal/kg for patients >/=60 years of age. Maintenance hemodialysis patients should be prescribed 1.2 g protein/kg/d; chronic peritoneal dialysis patients should be prescribed 1.2 to 1.3 g protein/kg/d. For non-dialyzed patients with CRF (glomerular filtration rate <25 mL/min), 0.60 g protein/kg/d should be prescribed. For patients who will not accept such a diet or are unable to maintain an adequate energy intake on that diet, a protein intake of up to 0.75 g protein/kg/d may be prescribed. At least 50% of the protein intake for all of these patients should be of high biologic value. A guideline concerning indications for inaugurating maintenance dialysis treatment or renal transplantation on the basis of deteriorating nutritional status is also given.

Relationship between nutritional status and the glomerular filtration rate: results from the MDRD study

BACKGROUND

The relationship between the protein-energy nutritional status and renal function was assessed in 1785 clinically stable patients with moderate to advanced chronic renal failure who were evaluated during the baseline phase of the Modification of Diet in Renal Disease Study. Their mean +/- SD glomerular filtration rate (GFR) was 39.8 +/- 21.1 mL/min/1.73 m2.

METHODS

The GFR was determined by 121I-iothalamate clearance and was correlated with dietary and nutritional parameters estimated from diet records, biochemistry measurements, and anthropometry.

RESULTS

The following parameters correlated directly with the GFR in both men and women: dietary protein intake estimated from the urea nitrogen appearance, dietary protein and energy intake estimated from dietary diaries, serum albumin, transferrin, percentage body fat, skinfold thickness, and urine creatinine excretion. Serum total cholesterol, actual and relative body weights, body mass index, and arm muscle area also correlated with the GFR in men. The relationships generally persisted after statistically controlling for reported efforts to restrict diets. Compared with patients with GFR > 37 mL/min/1.73 m2, the means of several nutritional parameters were significantly lower for GFR between 21 and 37 mL/min/1.73 m2, and lower still for GFRs under 21 mL/min/1.73 m2. In multivariable regression analyses, the association of GFR with several of the anthropometric and biochemical nutritional parameters was either attenuated or eliminated completely after controlling for protein and energy intakes, which were themselves strongly associated with many of the nutritional parameters. On the other hand, few patients showed evidence for actual protein-energy malnutrition.

CONCLUSIONS

These cross-sectional findings suggest that in patients with chronic renal disease, dietary protein and energy intakes and serum and anthropometric measures of protein-energy nutritional status progressively decline as the GFR decreases. The reduced protein and energy intakes, as GFR falls, may contribute to the decline in many of the nutritional measures.