Effect of medium cut-off and high-flux hemodialysis membranes on blood pressure assessed by ambulatory blood pressure monitoring

BACKGROUND

Hypertension is one of the most critical risk factors for cardiovascular disease, which is the leading cause of death in hemodialysis (HD) patients. Medium cut-off (MCO) membrane increases the clearance of medium molecules, which could improve blood pressure (BP) control. This study aimed to compare the effect of MCO and high-flux hemodialysis membranes on BP assessed by ambulatory blood pressure monitoring (ABPM).

METHODS

This is a pre-established secondary analysis of a 28-week, randomized, open-label crossover clinical trial. Patients were randomized to HD with MCO or high-flux membranes over 12 weeks, followed by a 4-week washout period, and then switched to the alternate membrane treatment for 12 weeks. ABPM was started before the HD session and ended at least 24 h later in weeks 1, 12, 16, and 28.

RESULTS

32 patients, 59% male, with a mean age of 52.7 years, and 40% with unknown CKD etiology, were enrolled. The dialysis vintage was 8 years, and more than 70% of the patients had hypertension. Regarding 24-h BP control, morning diastolic BP showed an increase in the high-flux compared to stability in the MCO group (interaction effect, p = 0.039). The adjusted ANOVA models showed no significant difference in the morning BP levels between the groups. Considering only the period of the HD session, patients in the MCO, compared to those in the high-flux membrane group, showed greater BP stability during dialysis, characterized by smaller variation in the pre-post HD systolic and minimum systolic BP (treatment effect, p = 0.039, and p = 0.023, respectively).

CONCLUSIONS

MCO membrane seems to have a beneficial effect on morning BP and favors better BP stability during HD sessions.

Effect of Hemodiafiltration on Self-Reported Sleep Duration: Results from a Randomized Controlled Trial

INTRODUCTION

Dialysis patients suffer from poor sleep duration and quality. We examined the self-reported sleep duration in patients randomized to either high-volume hemodiafiltration (HDF) or high flux hemodialysis (HD).

METHODS

Patients from 13 Brazilian dialysis clinics were enrolled in the HDFIT randomized controlled trial (RCT) investigating the impact of HDF on physical activity and self-reported outcomes. Self-reported sleep duration was taken from patient diaries recording sleep start and end time over a week during baseline, months 3 and 6, respectively. Sleep duration was analyzed by shift and nights relative to dialysis.

RESULTS

The HDFIT study enrolled 197 patients; sleep data were available in 173 patients (87 HD; 86 HDF). Patients' age was 53 ± 15 years, 57% were white, 72% were male, 34% had diabetes, Kt/V was 1.54 ± 0.40, and albumin 3.97 ± 0.36 g/dL. Most patients reported sleeping 510-530 min/night. At 3 months, HDF patients slept 513 ± 71 min/night, HD patients 518 ± 76 min/night. At 6 months, HDF patients slept 532 ± 74 min/night, HD patients 519 ± 80 min/night. At baseline, 1st shift patients slept 406 ± 86 min the night before HD, 534 ± 64 min the night after HD, and 496 ± 99 min the night between 2 non-HD days. Compared to patients in the 2nd and 3rd shifts, patients dialyzed in the 1st shift slept less in the night before dialysis. Similar patterns were seen after 3 and 6 months.

CONCLUSION

In our RCT, the dialysis modality (HDF vs. HD) had no effect on self-reported sleep duration. In both groups, dialysis in the 1st shift adversely affected self reported sleep duration.

Ventricular arrhythmia in chronic kidney disease patients

Patients with chronic kidney disease (CKD) are susceptible to the occurrence of ventricular arrhythmias. The leading cause of death in dialysis patients is cardiac arrhythmias. The pathophysiology of arrhythmias in this population is complex and seems to be related to structural cardiac abnormalities caused by CKD, associated with several triggers, such as water and electrolyte disorders, hormonal conditions, arrhythmogenic drugs, and the dialysis procedure itself. Little is known about the clinical outcomes in CKD patients with asymptomatic ventricular arrhythmias. The results of treatments with anti-arrhythmic drugs and invasive devices are controversial in these patients, according to the available literature. The aim of this study was to review this often-neglected topic, which is of special importance in the CKD population.

Hepcidin: an important iron metabolism regulator in chronic kidney disease

Anemia is a common complication and its impact on morbimortality in patients with chronic kidney disease (CKD) is well known. The discovery of hepcidin and its functions has contributed to a better understanding of iron metabolism disorders in CKD anemia. Hepcidin is a peptide mainly produced by hepatocytes and, through a connection with ferroportin, it regulates iron absorption in the duodenum and its release of stock cells. High hepcidin concentrations described in patients with CKD, especially in more advanced stages are attributed to decreased renal excretion and increased production. The elevation of hepcidin has been associated with infection, inflammation, atherosclerosis, insulin resistance and oxidative stress. Some strategies were tested to reduce the effects of hepcidin in patients with CKD, however more studies are necessary to assess the impact of its modulation in the management of anemia in this population. Resumo Anemia é uma complicação frequente e seu impacto na morbimortalidade é bem conhecido em pacientes com doença renal crônica (DRC). A descoberta da hepcidina e de suas funções contribuíram para melhor compreensão dos distúrbios do metabolismo de ferro na anemia da DRC. Hepcidina é um peptídeo produzido principalmente pelos hepatócitos, e através de sua ligação com a ferroportina, regula a absorção de ferro no duodeno e sua liberação das células de estoque. Altas concentrações de hepcidina descritas em pacientes com DRC, principalmente em estádios mais avançados, são atribuídas à diminuição da excreção renal e ao aumento de sua produção. Elevação de hepcidina tem sido associada à ocorrência de infecção, inflamação, aterosclerose, resistência à insulina e estresse oxidativo. Algumas estratégias foram testadas para diminuir os efeitos da hepcidina em pacientes com DRC, entretanto, serão necessários mais estudos para avaliar o impacto de sua modulação no manejo da anemia nessa população.

There Is No Impact of Diabetes on the Endothelial Function of Chronic Kidney Disease Patients

BACKGROUND

Patients with chronic kidney disease (CKD) and type 2 diabetes mellitus (DM) have increased risk of endothelial dysfunction, cardiovascular disease, and mortality. Several studies have separately analyzed endothelial function in these populations. However, data of patients with both CKD and DM are scarce. The aim of this study was to evaluate whether the presence of DM has any additional effect on the endothelial dysfunction of CKD patients.

METHODS

We measured endothelial progenitor cells (EPCs), stromal-derived factor 1 alpha (SDF-1α), serum and urinary nitric oxide (NO), flow-mediated dilation (FMD), and pulse wave velocity (PWV) in 37 CKD patients with DM (CKD-DM group) and in 37 without DM (CKD group).

RESULTS

CKD-DM group had a higher prevalence of obesity (P < 0.01), previous myocardial infarction (P = 0.02), myocardial revascularization (P = 0.04), and a trend for more peripheral artery disease (P = 0.07). Additionally, CKD-DM group had higher EPC (P = 0.001) and PWV (P < 0.001) values. On the other hand, no difference in SDF-1α and serum or urinary NO and FMD was observed between the groups.

CONCLUSIONS

Endothelial dysfunction is frequent in CKD patients, and an additive effect of diabetes cannot be implicated, suggesting the predominant role of uremia in this condition.

Uremia Retention Molecules and Clinical Outcomes

Chronic kidney disease is characterized by the accumulation of organic compounds in the bloodstream that may exert a variety of toxic effects in the body. These compounds, collectively known as uremic toxins, may be classified according to their physicochemical properties as free water-soluble low molecular weight molecules, middle molecules or protein-bound uremic toxins. Most of these retention molecules, due to either their size and/or binding to protein, constitute a complex therapeutic challenge to the nephrologist, particularly in end-stage renal disease, because of their limited removal by conventional dialysis therapies. Therefore, we review in this article the current clinical evidences that have supported the important role of uremic toxins in uremia by contributing to the adverse outcomes related to chronic kidney disease, such as increased mortality and cardiovascular events, as well as renal impairment progression that cannot be solely explained by traditional risk factors. These observations have ultimately contributed to testing new therapeutic targets, such as the gut, and the development of modern dialysis strategies to manage chronic kidney disease patients.

A Novel Missense GLA Mutation (p.G35V) Detected in Hemodialysis Screening Leads to Severe Systemic Manifestations of Fabry Disease in Men and Women

BACKGROUND/AIMS

Fabry disease (FD), an X-linked lysosomal storage disorder, leads to accumulation of globotriaosylceramide. Screening in dialysis patients may identify genetic variants of unknown clinical significance. We aimed to characterize the pathogenicity of a novel GLA gene mutation identified during hemodialysis screening and the histologic findings of early Fabry nephropathy.

METHODS

One out of 108 male hemodialysis patients screened for FD presented low α-galactosidase A activity. A novel missense mutation (p.G35V) in the GLA gene was detected. Family screening identified 11 additional cases (8 women). Clinical investigation was conducted in 10 patients (index case and 9 relatives). Pathogenicity of the new mutation was investigated by clinical and laboratory tests, cardiac and cranial magnetic resonance imaging, and kidney biopsy.

RESULTS

Cardiac manifestations were detected in most patient from both genders, such as left ventricular hypertrophy and short PR interval. White matter lesion was present in 3 women. Pulvinar lesion of the thalamus and ischemic stroke were detected in male patients. Abnormal glomerular filtration rate (GFR) and/or albuminuria were present in 5 patients (3 women). Renal biopsies (n = 7) revealed globotriaosylceramide deposits in different cell types and foot processes effacement in all patients, including women with normal albuminuria. Despite a normal GFR, tubulointerstitial fibrosis ranging from 5 to 20% was present in young women and men with normal or high albuminuria, respectively.

CONCLUSION

The novel missense mutation p.G35V leads to severe systemic manifestations of FD in men and women. Kidney histological changes, including tubulointerstitial fibrosis, may predate albuminuria and GFR changes in adult women. Novel non-invasive markers are required for early detection of Fabry nephropathy.

The shift from high to low turnover bone disease after parathyroidectomy is associated with the progression of vascular calcification in hemodialysis patients: A 12-month follow-up study

Parathyroidectomy (PTX) may cause low levels of PTH, leading to an excessive reduction of bone turnover, which is associated with poor outcomes in dialysis patients, including vascular calcification (VC). We aimed to prospectively investigate the impact of PTX on bone remodeling and its potential consequence on the progression of VC in hemodialysis patients. In this prospective study, 19 hemodialysis patients with severe secondary hyperparathyroidism (sHPT) were evaluated. All patients underwent laboratorial tests and coronary tomography at baseline and, 6 and 12 months after PTX; bone biopsy was performed at baseline and 12-month. At baseline, all patients had increased PTH levels up to 2500 pg/mL and high turnover bone disease in their bone biopsies. Fourteen (74%) patients had VC. During the follow-up, there was a significant decrease of PTH at 6 and 12-month. At 12-month, 90% of the patients evolved to low turnover bone disease. During the period of the hungry bone syndrome (first 6 months), no change of coronary calcium score was observed. However, calcium score increased significantly thereafter (12^th month). There was an association between VC progression and the severity of low turnover bone disease. In conclusion, the shift from high to low turnover bone disease after PTX occurs in parallel to VC progression, contributing to the understanding of the complex pathophysiology involving mineral metabolism and cardiovascular disease in hemodialysis patients.

Asymptomatic Ventricular Arrhythmia and Clinical Outcomes in Chronic Kidney Disease: A Pilot Study

BACKGROUND/AIMS

Ventricular arrhythmia is associated with increased risk of cardiovascular events and death in the general population. Sudden death is a leading cause of death in end-stage renal disease. We aimed at evaluating the effects of ventricular arrhythmia on clinical outcomes in patients with earlier stages of chronic kidney disease (CKD).

METHODS

In a prospective study of 109 nondialyzed CKD patients (estimated glomerular filtration rate 34.8 ± 16.1 ml/min/1.73 m², 57 ± 11.4 years, 61% male, 24% diabetics), we tested the hypothesis that the presence of subclinical complex ventricular arrhythmia, assessed by 24-hour electrocardiogram, is associated with increased risks of cardiovascular events, hospitalization, and death and with their composite outcome during 24 months of follow-up. Complex ventricular arrhythmia was defined as the presence of multifocal ventricular extrasystoles, paired ventricular extrasystoles, nonsustained ventricular tachycardia, or R wave over T wave.

RESULTS

We identified complex ventricular arrhythmia in 14% of participants at baseline. During follow-up, 11 cardiovascular events, 15 hospitalizations, and 4 deaths occurred. The presence of complex ventricular arrhythmia was associated with cardiovascular events (p < 0.001), hospitalization (p = 0.018), mortality (p < 0.001), and the composite outcome (p < 0.001). In multivariate Cox regression analysis, adjusting for demographic characteristics, complex ventricular arrhythmia was associated with increased risk of the composite outcome (HR 4.40; 95% CI 1.60-12.12; p = 0.004).

CONCLUSION

In this pilot study, the presence of asymptomatic complex ventricular arrhythmia was associated with poor clinical outcomes in nondialyzed CKD patients.

Association between indoxyl sulfate and bone histomorphometry in pre-dialysis chronic kidney disease patients

INTRODUCTION

Experimental studies have suggested that indoxyl sulfate (IS), a protein-bound uremic toxin, may be involved in the development of renal osteodystrophy.

OBJECTIVE

evaluate the association between IS levels and biochemical parameters related to mineral metabolism and bone histomorphometry in a cohort of pre-dialysis chronic kidney disease (CKD) patients.

METHODS

This is a post-hoc analysis of an observational study evaluating the association between coronary calcification and bone biopsy findings in 49 patients (age: 52 ± 10 years; 67% male; estimated glomerular filtration rate: 36 ± 17 ml/min). Serum levels of IS were measured.

RESULTS

Patients at CKD stages 2 and 3 presented remarkably low bone formation rate. Patients at CKD stages 4 and 5 presented significantly higher osteoid volume, osteoblast and osteoclast surface, bone fibrosis volume and bone formation rate and a lower mineralization lag time than CKD stage 2 and 3 patients. We observed a positive association between IS levels on one hand and the bone formation rate, osteoid volume, osteoblast surface and bone fibrosis volume on the other. Multivariate regression models confirmed that the associations between IS levels and osteoblast surface and bone fibrosis volume were both independent of demographic and biochemical characteristics of the study population. A similar trend was observed for the bone formation rate.

CONCLUSION

Our findings demonstrated that IS is positively associated with bone formation rate in pre-dialysis CKD patients.

Value of renal cortical thickness as a predictor of renal function impairment in chronic renal disease patients

Objective

To determine the presence of linear relationship between renal cortical thickness, bipolar length, and parenchymal thickness in chronic kidney disease patients presenting with different estimated glomerular filtration rates (GFRs) and to assess the reproducibility of these measurements using ultrasonography.

Materials and Methods

Ultrasonography was performed in 54 chronic renal failure patients. The scans were performed by two independent and blinded radiologists. The estimated GFR was calculated using the Cockcroft-Gault equation. Interobserver agreement was calculated and a linear correlation coefficient (r) was determined in order to establish the relationship between the different renal measurements and estimated GFR.

Results

The correlation between GFR and measurements of renal cortical thickness, bipolar length, and parenchymal thickness was, respectively, moderate (r = 0.478; p < 0.001), poor (r = 0.380; p = 0.004), and poor (r = 0.277; p = 0.116). The interobserver agreement was considered excellent (0.754) for measurements of cortical thickness and bipolar length (0.833), and satisfactory for parenchymal thickness (0.523).

Conclusion

The interobserver reproducibility for renal measurements obtained was good. A moderate correlation was observed between estimated GFR and cortical thickness, but bipolar length and parenchymal thickness were poorly correlated.

Visceral obesity assessed by computed tomography predicts cardiovascular events in chronic kidney disease patients

BACKGROUND AND AIM

Cardiovascular disease is the leading cause of death among patients with chronic kidney disease (CKD). Although there is emerging evidence that excess visceral fat is associated with a cluster of cardiometabolic abnormalities in these patients, the impact of visceral obesity evaluated by a gold-standard method on future outcomes has not been studied. We aimed to investigate whether visceral obesity assessed by computed tomography was able to predict cardiovascular events in CKD patients.

METHODS AND RESULTS

We studied 113 nondialyzed CKD patients [60% men; 31% diabetics; age 55.3 ± 11.3 years; body mass index (BMI) 27.2 ± 5.3 kg/m(2); estimated glomerular filtration rate (GFR) 33.7 ± 13.6 ml/min/1.73 m(2)]. Visceral and subcutaneous abdominal fat were assessed by computed tomography at L4-L5. Visceral to subcutaneous fat ratio >0.55 (highest tertile cut-off) was defined as visceral obesity. Cardiovascular events including acute myocardial infarction, angina, arrhythmia, uncontrolled blood pressure, stroke and cardiac failure were recorded during 24 months. Cardiovascular events were 3-fold higher in patients with visceral obesity than in those without visceral obesity. The Kaplan-Meier analysis indicated that patients with visceral obesity had shorter cardiovascular event-free time than those without visceral obesity (P = 0.021). In the univariate Cox analysis, visceral obesity was associated with higher risk of cardiovascular events (hazard ratio = 3.4; 95% confidence interval = 1.1-10.5; P = 0.03). The prognostic power of visceral obesity for cardiovascular events remained significant after adjustments for sex, age, diabetes, previous cardiovascular disease, smoking, sedentary lifestyle, BMI, GFR, hypertension, dyslipidemia and inflammation.

CONCLUSION

Visceral obesity assessed by computed tomography was a predictor of cardiovascular events in CKD patients.

Prevalence of ventricular arrhythmia and its associated factors in nondialyzed chronic kidney disease patients

BACKGROUND AND OBJECTIVES

Sudden cardiac death is the most common cause of mortality in chronic kidney disease patients, and it occurs mostly due to ventricular arrhythmias. In this study, we aimed at investigating the prevalence of ventricular arrhythmia and the factors associated with its occurrence in nondialyzed chronic kidney disease patients.

DESIGN SETTING PARTICIPANTS AND MEASUREMENTS

This cross-sectional study evaluated 111 chronic kidney disease patients (estimated glomerular filtration rate 34.7±16.1 mL/min/1.73 m(2), 57±11.4 years, 60% male, 24% diabetics). Ventricular arrhythmia was assessed by 24-hour electrocardiogram. Left ventricular hypertrophy (echocardiogram), 24-hour ambulatory blood pressure monitoring, and coronary artery calcification (multi-slice computed tomography) and laboratory parameters were also evaluated.

RESULTS

Ventricular arrhythmia was found in 35% of the patients. Non-controlled hypertension was observed in 21%, absence of systolic decency in 29%, left ventricular hypertrophy in 27%, systolic dysfunction in 10%, and coronary artery calcification in 49%. Patients with ventricular arrhythmia were older (p<0.001), predominantly men (p = 0.009), had higher estimated glomerular filtration rate (p = 0.03) and hemoglobin (p = 0.005), and lower intact parathyroid hormone (p = 0.024) and triglycerides (p = 0.011) when compared to patients without ventricular arrhythmia. In addition, a higher left ventricular mass index (p = 0.002) and coronary calcium score (p = 0.002), and a lower ejection fraction (p = 0.001) were observed among patients with ventricular arrhythmia. In the multiple logistic regression analysis, aging, increased hemoglobin levels and reduced ejection fraction were independently related to the presence of ventricular arrhythmia.

CONCLUSIONS

Ventricular arrhythmia is prevalent in nondialyzed chronic kidney disease patients. Age, hemoglobin levels and ejection fraction were the factors associated with ventricular arrhythmia in these patients.

Comparison of trisodium citrate and heparin as catheter-locking solution in hemodialysis patients

INTRODUCTION

The high incidence of patients beginning dialysis treatment with venous catheters, as well as the growing number of patients with permanent catheter access, has increased catheter- related blood infections and their consequences. Thus the search for substances with anticoagulant properties that also prevent catheter contamination is necessary.

OBJECTIVE

This study aimed at comparing heparin and trisodium citrate used as long-term catheter locking solutions regarding the occurrence of pyrogenic reaction, bacteremia, infection- related hospitalizations, thrombosis, and death.

METHODS

Retrospective study on the infection data from the Infection and Adverse Event Prevention Control Program registry, which included all hemodialysis patients using long-term catheters from April, 2006 to March, 2008. During the first 365 days, catheters were locked with heparin (Heparin group) and, during the following 365 days, with 46.7% trisodium citrate (Citrate group). Sixty-five patients were included in the study using 92 catheters. The groups were compared regarding the occurrence of pyrogenic reaction, bacteremia, hospitalization, catheter thrombosis, and death.

RESULTS

The catheter-related bacteremia episodes were significantly lower and hospitalization time was significantly shorter in the Citrate group when compared with those in the Heparin group. A tendency towards a lower occurrence of access site infection-related hospitalization was observed in the Citrate group (p = 0.055), and no difference was observed in catheter thrombosis leading to dysfunction between groups. Bacteremia-free and hospitalization-free times were longer in the Citrate group. The occurrence of bacteremia was associated with the presence of diabetes and heparin use. In multivariate analysis, being in the Heparin group was the only factor associated with bacteremia.

CONCLUSION

The use of 46.7% citrate solution effectively reduced bacteremia episodes and hospitalization in chronic kidney disease patients on hemodialysis with long-term catheters.

Fibroblast growth factor 23 in chronic kidney disease: bridging the gap between bone mineral metabolism and left ventricular hypertrophy

BACKGROUND

Left ventricular hypertrophy (LVH) is a major cardiovascular complication in chronic kidney disease (CKD) patients. For a successful management of LVH, the comprehensive understanding of the classical and the new emerging factors associated with LVH is of paramount importance. The aim of the present study was to evaluate the clinical correlates of bone mineral metabolism with the occurrence of LVH in nondialyzed CKD patients.

METHODS

This cross-sectional study included 96 patients with stages 2-4 CKD. Demographic characteristics, clinical profiles, laboratory tests and transthoracic echocardiogram were performed.

RESULTS

LVH was observed in 36% of the patients. Patients with LVH were older, had a higher prevalence of hypertension, and higher levels of intact parathormone, fibroblast growth factor 23 and C-reactive protein. Serum phosphorus, alkaline phosphatase and vitamin D were not associated with the presence of LVH. In the multiple logistic regression analyses only FGF23 remained as a variable independently associated with LVH.

CONCLUSION

We confirmed the high prevalence of LVH in nondialyzed CKD patients and showed that FGF23, an early marker of phosphorus load, was an important factor associated with LVH in these patients. Monitoring of FGF23 could be important for the management of LVH in this population.

KDIGO CKD-MBD Discussion forum: the Brazilian perspective

On November 14th, 2009, the Brazilian Society of Nephrology coordinated the Brazilian Discussion Meeting on the new KDIGO (Kidney Disease: Improving Global Outcomes) guidelines. The purpose of this meeting, which was attended by 64 nephrologists, was to discuss these new guidelines from the Brazilian perspective. This meeting was supported by an unrestricted grant of the biotechnology company Genzyme, which did not have access to the meeting room or to the discussion sections. This article brings a summary of the KDIGO guidelines and of the discussions by the attendees.

Phosphate binder impact on bone remodeling and coronary calcification--results from the BRiC study

BACKGROUND AND AIMS

Calcium-containing phosphate binders have been shown to increase the progression of vascular calcification in hemodialysis patients. This is a prospective study that compares the effects of calcium acetate and sevelamer on coronary calcification (CAC) and bone histology.

METHODS

101 hemodialysis patients were randomized for each phosphate binder and submitted to multislice coronary tomographies and bone biopsies at entry and 12 months.

RESULTS

The 71 patients who concluded the study had similar baseline characteristics. On follow-up, the sevelamer group had higher levels of intact parathyroid hormone (498 +/- 352 vs. 326 +/- 236 pg/ml, p = 0.017), bone alkaline phosphatase (38 +/- 24 vs. 28 +/- 15 U/l, p = 0.03) and deoxypyridinoline (135 +/- 107 vs. 89 +/- 71 nmol/l, p = 0.03) and lower LDL cholesterol (74 +/- 21 vs. 91 +/- 28 mg/dl, p = 0.015). Phosphorus (5.8 +/- 1.0 vs. 6 +/- 1.0 mg/dl, p = 0.47) and calcium (1.27 +/- 0.07 vs. 1.23 +/- 0.08 mmol/l, p = 0.68) levels did not differ between groups. CAC progression (35 vs. 24%, p = 0.94) and bone histological diagnosis at baseline and 12 months were similar in both groups. Patients of the sevelamer group with a high turnover at baseline had an increase in bone resorption (eroded surface, ES/BS = 9.0 +/- 5.9 vs. 13.1 +/- 9.5%, p = 0.05), whereas patients of both groups with low turnover at baseline had an improvement in bone formation rate (BFR/BS = 0.015 +/- 0.016 vs. 0.062 +/- 0.078, p = 0.003 for calcium and 0.017 +/- 0.016 vs. 0.071 +/- 0.084 microm(3)/microm(2)/day, p = 0.010 for sevelamer).

CONCLUSIONS

There was no difference in CAC progression or changes in bone remodeling between the calcium and the sevelamer groups.

Evaluation of the role of severe hyperparathyroidism on coronary artery calcification in dialysis patients

BACKGROUND

Chronic kidney disease (CKD) patients are at a high risk of dying from a cardiovascular event, mainly due to coronary calcification. Among the various uremic and dialysis-specific risk factors for coronary calcification are mineral metabolism disorders. The role that secondary hyperparathyroidism (SHPT) consequent to the altered calcium and phosphate metabolism plays in the pathogenesis of coronary calcification remains unclear. The aim of this study was to evaluate the prevalence of coronary artery calcification in dialysis patients with severe SHPT submitted to multislice coronary tomography (MSCT) and to identify risk factors for coronary calcification.

METHODS

This study involved 23 adult dialysis patients (age >18 years) with severe SHPT who were candidates for parathyroidectomy (PTX). All were submitted to MSCT and bone densitometry during the month preceding PTX. Fasting blood samples were collected immediately before surgery. Markers of mineral metabolism, including ionized calcium, phosphorus, alkaline phosphatase, intact-parathyroid hormone (iPTH), osteoprotegerin (OPG) and soluble receptor activator of nuclear factor-kappaB ligand, were analyzed. Dyslipidemia was assessed by determination of LDL, HDL and VLDL-cholesterol and triglyceride levels. Agatston units (AU) were used to calculate calcium scores.

RESULTS

No coronary calcification was found in 30% of the patients. Moderate (calcium score > 100 AU) and severe (calcium score >400 AU) calcification was observed in 12 and 36% of the patients, respectively. In the univariate analysis, calcium volume correlated positively with VLDL-cholesterol (r = 0.44; p = 0.03) and, albeit less than significantly, with age (r = 0.35; p = 0.09), triglycerides (r = 0.39; p = 0.05) and Framingham risk index (r = 0.37; p = 0.07). We also found that OPG correlated negatively with bone mineral density at the L2-L4 lumbar vertebrae (r = -0.54; p = 0.007) and femoral neck (r = -0.43; p = 0.04).

CONCLUSIONS

Although high levels of PTH should be considered a risk factor for cardiovascular death, the real role of severe SHPT on coronary calcification is to be clarified.

Resting energy expenditure and its determinants in hemodialysis patients

OBJECTIVE

Chronic kidney disease is associated with several metabolic disturbances that can affect energy metabolism. As resting energy expenditure (REE) is scarcely investigated in patients on hemodialysis (HD) therapy, we aimed to evaluate the REE and its determinants in HD patients.

DESIGN

Cross-sectional study.

SETTING

Dialysis Unit of the Nephrology Division, Federal University of São Paulo, Brazil.

SUBJECTS

The study included 55 patients (28 male, 41.4+/-12.6 years old) undergoing HD therapy thrice weekly for at least 2 months, and 55 healthy individuals pair matched for age and gender. Subjects underwent fasting blood tests, as well as nutritional assessment, and the REE was assessed by indirect calorimetry.

RESULTS

REE of HD patients was similar to that of pair-matched controls (1379+/-272 and 1440+/-259 kcal/day, respectively), even when adjusted for fat-free mass (P=0.24). REE of HD patients correlated positively with fat-free mass (r=0.74; P<0.001) and body mass index (r=0.37; P<0.01), and negatively with dialysis adequacy (r=-0.46; P<0.001). No significant univariate correlation was found between REE and age, dialysis vintage, serum creatinine, urea, albumin, bicarbonate, parathyroid hormone (PTH) or high-sensitivity C-reactive protein (CRP). In the multiple linear regression analysis, using REE as dependent variable, the final model showed that besides the well-recognized determinants of REE such as fat-free mass and age, PTH and CRP were the independent determinants of REE in HD patients (R (2)=0.64).

CONCLUSIONS

In this study, the REE of HD patients was similar to that of healthy individuals, even with the positive effect of secondary hyperparathyroidism and inflammation on REE of these patients.

Coronary artery calcification, systemic inflammation markers and mineral metabolism in a peritoneal dialysis population

AIMS

To assess the prevalence of coronary artery calcification (CAC) in peritoneal dialysis (PD) patients and to determine whether comorbidities such as inflammation, dyslipidemia and mineral metabolism disorders correlate with its development.

METHODS

Forty-nine PD patients (45% male; median age, 52 years) were submitted to multislice computed tomography. Inflammatory markers, anti-oxidized LDL antibody, calcium-phosphate balance and lipid profiles were assessed.

RESULTS

Twenty-nine patients (59.2%) presented CAC (median calcium score, 234.7 Agatston units). Patients with CAC were older than those without, more frequently presented a history of coronary artery disease or hypertension and had lower HDL cholesterol levels, as well as presenting higher levels of osteoprotegerin and LDL oxidation. The logistic regression revealed that the independent determinants of CAC were age (odds ratio = 1.12; p = 0.006) and number of prescribed anti-hypertensive drugs (odds ratio = 2.38; p = 0.048). When the population was stratified by calcium score quartile, soluble Fas levels were significantly higher in patients with severe calcification. In patients younger than 45, CAC correlated positively with phosphorus levels (r = 0.52; p = 0.04).

CONCLUSION

In PD patients, CAC is highly prevalent. Our results indicate that conditions such as inflammation and mineral disturbances are associated with its development.

Nutritional Parameters and Mortality in Incident Hemodialysis Patients

OBJECTIVE

To evaluate the impact of nutritional parameters at the time of initiation of hemodialysis (HD) on mortality.

DESIGN

Retrospective study.

SETTING

Dialysis Unit of the Federal University of Sao Paulo, Oswaldo Ramos Foundation.

PATIENTS

Three hundred forty-four incident HD patients (60.5% male, 26% diabetic) with the first nutritional evaluation performed before completing 3 months of onset of HD were included.

METHODS

The study consisted of baseline measurements of several nutritional parameters (triceps skinfold thickness [TSF], midarm muscle circumference [MAMC], body mass index [BMI], serum albumin, serum creatinine, and protein and energy intake assessed by 3-day food diary) and records of outcome (death) over a period of 10 years.

RESULTS

Muscle and/or fat depletion was observed in 51% of the studied patients, according to the percent standard of MAMC and TSF, respectively. Presence of diabetes, age over 60 years, serum albumin < 3.5 g/dL, MAMC adequacy < 90%, protein intake < 1.0 g/kg/d, and energy intake < 25 kcal/kg/d were associated with worse survival. When patients were analyzed according to tertiles of dialysis vintage, BMI > or = 25 (calculated as kg/m2) had a negative impact on survival only in the highest tertile (> 2.45 years). Patients with BMI < 25 and MAMC adequacy > or = 90% showed the best survival over the study period, and those with BMI > or = 25 but MAMC adequacy < 90% had the worst survival (P = .004). In the multivariate survival analysis adjusting for diabetes, advanced age, and hypoalbuminemia, the reduced MAMC (P = .008) and the low energy intake (P = .03) were independent predictors of death in incident HD patients.

CONCLUSIONS

Reduced MAMC and low energy intake at the beginning of chronic dialysis are risk factors for mortality. A negative effect of high BMI on survival was associated with reduced MAMC and longer dialysis vintage.

Coronary calcification in hemodialysis patients: the contribution of traditional and uremia-related risk factors

BACKGROUND

Coronary artery calcification is a common feature of atherosclerosis, occurring in 90% of angiographically significant lesions. There is recent evidence that coronary artery calcification is frequent in hemodialysis patients and it has been suggested that this increased incidence may be associated to uremia-related factors. The development and progression of coronary artery calcification is similar to osteogenesis. The aim of this study was to evaluate the relationship between coronary artery calcification, uremia-related factors, and bone histomorphometry in hemodialysis patients.

METHODS

A total of 101 hemodialysis patients were assessed for biochemical markers of inflammation, oxidative stress, and bone metabolism. Subsequently, they were submitted to multislice coronary tomography (MSCT) and transiliac bone biopsy.

RESULTS

The median calcium score was 116.2 (range 0 to 5547). Fifty-two percent of the patients showed moderate and severe coronary artery calcification, 20% had calcium scores greater than 1000. In univariate analysis, age (r= 0.57, P < 0.000001), osteoprotegerin (OPG) (r= 0.44, P= 0.00002), and body mass index (BMI) (r= 0.24, P= 0.01) correlated positively with calcium score. Bone trabecular volume and trabecular thickness correlated negatively with calcium score (r=-0.24, P= 0.02; r=-0.22, P= 0.03). There was a correlation of borderline significance between calcium score and C-reactive protein (CRP) (r= 0.18, P= 0.062). The multiple linear regression analysis identified OPG as the only variable independently associated with coronary artery calcification.

CONCLUSION

Coronary artery calcification is highly prevalent in the hemodialysis population and is associated with older age, higher BMI, inflammation and reduced trabecular bone volume. Higher OPG is independently associated with coronary artery calcification and may represent an incomplete self-defensive response to the progression of atherosclerosis in hemodialysis patients.

Is serum albumin a marker of nutritional status in hemodialysis patients without evidence of inflammation?

Hypoalbuminemia, a strong predictor of morbidity and mortality in hemodialysis patients, can be a consequence of a combination of malnutrition and inflammatory reactions. The purpose of this study was to analyze serum albumin as a marker of nutritional status in maintenance hemodialysis patients with no signs of inflammation. In a cross-sectional study, we selected 40 stable hemodialysis patients with normal levels of C-reactive protein (<0.8 mg/dL). The patients were classified as well nourished (65%) or malnourished (35%) according to the subjective global assessment. No significant differences were observed in serum albumin concentrations (immunoturbidimetric method) between well-nourished (4.3 +/- 0.3 g/dL) and malnourished (4.0 +/- 0.5 g/dL) patients, and the mean values were within the normal range in both groups. Albumin was inversely correlated with age (n=40; r=-0.32; P=0.02) and directly with energy intake (n=28; r=0.43; P=0.04). In this study, serum albumin did not discriminate well-nourished and malnourished hemodialysis patients without evidence of inflammation.

[Quality of life in chronic renal disease patients submitted to hemodialysis evaluated with SF-36 instrument]

Quality of life is a new concept in the health area and controversies exist about its application to clinical practice. Studies carried out in Brazil in the nephrology area have indicated the need for further investigations.

OBJECTIVE

To analyze the quality of life of patients with different times of hemodialysis.

METHODS

The study consisted of application of the questionnare SF-36, collection of demographic, socioeconomic and biochemical data, as well as of the clinical characteristics.

RESULTS

The study was conducted on 184 patients, 63% of them males, aged 46 15 years (X SD), with a hemodialysis time of 30 36 months; 48% had up to 4 years of schooling and 53% belonged to the economic-social classes D and E. Impairment of the different dimensions analyzed was observed, with the poorest results being obtained for Physical Aspects and Vitality. A negative correlation was detected between Age and Functional Capacity, Physical Aspects, Pain, and Vitality, and between Hemodialysis Time and Emotional Aspects. A positive correlation was observed between Schooling and Emotional Aspects and between Hemoglobin and Vitality. We observed that diabetic patients were older than non-diabetic patients and presented lower values for the Functional Capacity and General Health condition dimensions.

CONCLUSION

SF-36 proved to be a good instrument for the assessment of the quality of life of hemodialysis patients. The presence of a chronic disease, the need for continuous treatment over a long period of time, advanced age, and the presence of co-morbidities were factors that might interfere with the quality of life of this population.

Comparison of three methods for the determination of body fat in patients on long-term hemodialysis therapy

OBJECTIVE

To compare three simple methods of body composition analysis for the assessment of body fat in patients on long-term hemodialysis therapy.

DESIGN

Cross-sectional study using the skinfold thickness, bioelectrical impedance analysis, and near-infrared interactance techniques after a hemodialysis session.

SUBJECTS/SETTING

Ninety clinically stable patients (57 male/33 female) undergoing hemodialysis at the Dialysis Unit of the Federal University of São Paulo.

STATISTICAL ANALYSIS

Analysis of variance, intraclass correlation coefficient, and Bland-Altman plot analysis were used for the comparative analysis between the methods.

RESULTS

Body fat measurements obtained by skinfold thickness (13.5+/-6.2 kg) and bioelectrical impedance analysis (13.7+/-6.7 kg) were similar, whereas those measured by near-infrared interactance (11.3+/-5.1 kg) were significantly lower in comparison with skinfold thickness and bioelectrical impedance analysis (P<.001). The strongest intraclass correlation coefficient was found between bioelectrical impedance analysis and skinfold thickness (r=0.87), and near-infrared interactance vs skinfold thickness and bioelectrical impedance analysis methods yielded r=0.78 and r=0.76, respectively. Near-infrared interactance showed a progressive underestimation of body fat values in comparison with the bioelectrical impedance analysis technique in patients with higher amount of adiposity.

CONCLUSION

In our study, we cannot consider that one method of body composition analysis is more accurate than the other because we did not apply a gold standard method. However, the most simple, long-established, and inexpensive method of skinfold thickness seems to be still very useful to the dietitians' routine for assessing body fat in patients on long-term hemodialysis therapy.

[Nutritional condition in chronic renal failure patients treated by hemodialysis in Amazonas]

BACKGROUND

Chronic renal failure patients frequently show malnourishment.

OBJECTIVE

The food intake and the nutritional status of 165 chronic renal failure patients on maintenance hemodialysis were studied.

METHODS

Nutritional status of 165 patients were studied by anthropometry, biochemical measurements, protein nitrogen appearance rate (PNA) and a average food intake.

RESULTS

The results show that in mean the percent standard body weight, the body mass index (BMI), the mid arm muscle circumference (MAMC) and the triceps skinfold thickness (TSF) were adequate, however, 38% of women and 27% of men had the TSF bellow the 5th percentile; 39% of men and 2% of women presented MAMC bellow the 5th percent, showing that lose body fat in both sexs and the muscle stores in men. Energy intake was 29.5 +/- 10.2 Kcal/kg/day and 74% of the patients consumed less than 35 Kcal/kg/day, the recommended level for this population. Although the protein intake was in the recommended range (1.32 +/- 0.4 g/kg/day), 47% of the patients consumed less than 1.2 g/Kg/day. Mean serum albumin was 3.96 +/- 0.36 g/dL (normal value). According to TSF and of MAMC criteria (the reference was the 5th percentile), 74 (44.8%) patients were classified as malnourished.

CONCLUSIONS

The frequency of malnutrition is high in our population and the poor food intake may contribute to this condition.

Comparison of skinfold thicknesses and bioelectrical impedance analysis with dual-energy X-ray absorptiometry for the assessment of body fat in patients on long-term haemodialysis therapy

BACKGROUND

Body composition assessment in patients with chronic renal failure is of paramount importance since studies have demonstrated the association of protein-energy malnutrition with an increased morbidity and mortality in this population. However, practical and sensible indicators of body compartments are still needed for clinical purposes. Thus, we aimed to evaluate the simple methods of skinfold thicknesses (SKF) and bioelectrical impedance analysis (BIA), using dual-energy X-ray absorptiometry (DEXA) as a reference method, for the assessment of body fat in patients on long-term haemodialysis therapy.

METHODS

We studied 30 clinically stable patients (15 men/15 women) undergoing haemodialysis at the Dialysis Unit of the Federal University of São Paulo. Body fat assessment was performed by the SKF, BIA and DEXA methods after a haemodialysis session. Analysis of variance, intra-class correlation coefficient and Bland and Altman plot analysis were used for comparative analysis among the methods.

RESULTS

Body fat estimates by SKF (17.7 +/- 7.8 kg) and BIA (18.6 +/- 9.2 kg) were not significantly different from those obtained by DEXA (18.2 +/- 7.9 kg) considering the whole population. However, the BIA technique worked differently from DEXA when analysed by gender, measuring less fat content in men and higher fat content in women (P < 0.01). No differences were observed for SKF. Strong intra-class correlation coefficients (r) were found between DEXA with SKF (r = 0.94) and BIA (r = 0.91). DEXA showed a relatively good agreement with both SKF [0.47 +/- 2.8 (-5.0 to 6.0) kg] and BIA [-0.39 +/- 3.3 (-6.9 to 6.1) kg] in all patients according to the Bland and Altman plot analysis. However, considering gender, BIA showed greater mean prediction error of 1.93 +/- 2.5 (-3.0 to 6.8) kg for men and -2.71 +/- 2.3 (-7.2 to 1.8) kg for women.

CONCLUSIONS

The simple and long established method of SKF was preferable over BIA, which showed gender-specific variability in the assessment of body fat in patients undergoing haemodialysis. However, more comparative and longitudinal studies are needed to evaluate the applicability of these practical methods for monitoring body composition in the routine care of patients with chronic renal failure.