Bedeutung von PET und Kt/V für die Peritonealdialyse

PET should be monitored 4 weeks after the start of peritoneal dialysis (PD) and then yearly, and Kt/V every 3 months. PET makes it possible to determine different velocities of glucose absorption (from the dialysate) and of the transport of such low-molecular-weight substances as creatinine and urea (from blood to dialysate), and in particular to calculate the prognosis of the long-term ultrafiltration capacity of the peritoneum in each PD patient. Kt/V is a measure of the urea clearance both of the peritoneum and of the actual kidneys; it seems that preservation of any residual renal function has a more significant positive influence on patient survival and on the technical course than does an increase of the dialysis dose. It is accepted that PD is working efficiently when Kt/V is over 1.7. Besides PET and Kt/V clinical (well-being, eating behaviour, whether body weight is steady, functional capacity) and other (blood pressure, neurological status, degree of anaemia, calcium/phosphate ratio) criteria are also important in the evaluation of whether PD treatment is adequate.     

Ionic dialysance and quality control in hemodialysis

Quantification of dialysis is based on the measurement of effective urea clearance (K), dialysis dose (Kt) or normalized dialysis dose (Kt/V). During the last 20 years, Kt/V was the single parameter actually useful for quantifying dialysis efficiency, because it can be calculated from just blood or dialysate urea concentrations at the beginning and at the end of the dialysis session. However the calculation of the normalized dialysis dose (Kt/V) actually delivered to the patient cannot be performed during each dialysis session, because of the need of urea concentration measurements. Ionic dialysance is a new parameter easily measured on-line, non-invasively, automatically and without any cost during each dialysis session by a conductivity method. Because ionic dialysance has been proved equal to the effective urea clearance taking into account cardiopulmonary and access recirculation, it is becoming an actual quality-assurance parameter of the dialysis efficiency.     

Evaluation of methods to calculate dialysis dose in daily hemodialysis

Daily dialysis has shown excellent clinical results because a higher frequency of dialysis is more physiological. Different methods have been described to calculate dialysis dose which take into consideration change in frequency. The aim of this study was to calculate all dialysis dose possibilities and evaluate the better and practical options. Eight patients, 6 males and 2 females, on standard 4 to 5 hours thrice weekly on-line hemodiafiltration (S-OL-HDF) were switched to daily on-line hemodiafiltration (D-OL-HDF) 2 to 2.5 hours six times per week. Dialysis parameters were identical during both periods and only frequency and dialysis time of each session were changed. Time average concentration (TAC), time average deviation (TAD), normalized protein catabolic rate (nPCR), Kt/V, equilibrated Kt/V (eKt/V), equivalent renal urea clearance (EKR), standard Kt/V (stdKt/V), urea reduction ratio (URR), hemodialysis product and time off dialysis were measured. Daily on-line hemodiafiltration was well accepted and tolerated. Patients maintained the same TAC although TAD decreased from 9.7 +/- 2 in baseline to a 6.2 +/- 2 mg/dl after six months, p < 0.01. No significant changes were observed in weekly Kt/V and eKt/V throughout the study. However EKR, stdKt/V and weekly URR were increased during D-OL-HDF in 24-34%, 46% and 50%, respectively. Hemodialysis product was raised in a 95% and time off dialysis was reduced to half. CONCLUSION: Dialysis frequency is an important urea kinetic parameter which there are to take in consideration. It's necessary to use EKR, stdKt/V or weekly URR to calculate dialysis dose for an adequate comparison between different frequency dialysis schedules.     

Determination of the dose of dialysis with integrated modules in the same monitor

The "gold standard" method to measure the mass balance achieved during dialysis for a given solute is based on the total dialysate collection. This procedure is unfeasible and too cumbersome. For this reason, alternative methods have been proposed including the urea kinetic modelling (Kt/V), the measurement of effective ionic dialysance (Diascan), and the continuous spent sampling of dialysate (Quantiscan). The aim of this study was to compare the reliability and agreement of these two methods with the formulas proposed by the urea kinetic modelling for measuring the dialysis dose and others haemodialysis parameters. We studied 20 stable patients (16 men/4 women) dialyzed with a monitor equipped with the modules Diascan (DC) and Quantiscan (QC) (Integra. Hospal). The urea distribution volume (VD) was determined using anthropometric data (Watson equation) and QC data. Kt/V value was calculated according to Daurgidas 2nd generation formula corrected for the rebound (eKt/V), and using DC (Kt/VDC) and QC (Kt/VQC) data. The total mass of urea removed was calculated as 37,93 +/- 16 g/session. The VD calculated using Watson equation was 35.7 +/- 6.6 and the VDQC was 35.06 +/- 9.9. And they showed an significative correlation (r:0,82 p < 0.001). The (VDQC-VDWatson) difference was -0.64 +/- 5.8L (ns). Kt/VDC was equivalent to those of eKt/V (1.64 +/- 0.33 and 1.61 +/- 0.26, mean difference -0.02 +/- 0.29). However, Kt/VQC value was higher than eKt/V (1.67 +/- 0.22 and 1.61 +/- 0.26 mean difference 0.06 +/- 0.07 p < 0.01). Both values correlated highly (R2: 0.92 p < 0.001). Urea generation (C) calculated using UCM was 8.75 +/- 3.4 g/24 h and those calculated using QC was 8.64 +/- 3.21 g/24 h. Mean difference 0.10 +/- 1.14 (ns). G calculated by UCM correlated highly with that derived from QC (R2: 0.88 p < 0.001). In conclusion, Kt/VDC and Kt/VQC should be considered as valid measures for dialysis efficiency. However, the limits of agreement between Kt/VQC and eKt/V were closer than Kt/VDC.     

The adequacy of peritoneal dialysis in a single Chinese center

ObjectiveTo assess the adequacy of peritoneal dialysis in Chinese by analyzing the relationship between weekly urea kinetics (Kt/V) and clinical outcomes.MethodsA total of 146 patients on continuous ambulatory peritoneal dialysis for more than 6 months in the Shanghai Renji Hospital between July 1997 and March 1999 were enrolled into this study. They were assigned to three groups according to weekly Kt/V: Group A, Kt/V less than 1.7; Group B, Kt/V between 1.7 and 2; and Group C, Kt/V greater than 2. Patient and technique survivals were analyzed by using the log rank method.ResultsThe overall 2-year actuarial patient and technique survivals were 90% and 76%, respectively. The 2-year actuarial patient survival was 78% for Group A, 97% for Group B, and 96% for Group C (p<0.05). The 2-year technique survival was 56% for Group A, 88% for Group B, and 88% for Group C. Both actuarial patient and technique survivals in Group A were significantly lower (p<0.05) compared with the other two groups.ConclusionThe study showed that clinical outcomes in Groups B and C patients were similar. However, patients with weekly Kt/V values less than 1.7 had poorer clinical outcomes compared with patients from groups B and C. We conclude that Chinese patients who were receiving peritoneal ambulatory dialysis may benefit from weekly Kt/V greater than 1.7.     

ADEMEX and HEMO trials: where are we going?

Doubt has remained as to whether or not the K/DOQI recommended targets for adequacy of dialysis for peritoneal dialysis patients is appropriate (weekly Kt/V 2 + creatinine clearance 50-60 l/1.73 m(2)). The ADEMEX trial can be interpreted as indicating that lower targets might be acceptable. The HEMO trial, not yet published but presented in April 2002, casts doubts on the advantages of achieving higher than recommended small solute clearance targets. Taken together, these trials require that we broaden our concept of adequacy. There is also a risk of complacency with respect to dialysis adequacy because of these trials and this would be unwise.     

Cystatin C Levels in Functionally Anephric Patients Undergoing Dialysis: The Effect of Different Methods and Intensities

Background and objectives: Cystatin C, a low molecular weight protein, is produced by nucleated cells, filtered by glomeruli, and degraded by tubules at a constant rate. Its serum concentration has been proposed as a marker of GFR. Its size should make it dialyzable. It is hypothesized that serum cystatin C levels are influenced by the method and intensity of dialysis received.Design: This is a cross-sectional pilot study of cystatin C in functionally anephric dialysis patients. It was measured predialysis in 14 patients on conventional (3 to 5 h, 3 × wk) hemodialysis; eight on nocturnal hemodialysis (three to seven nights, 6 to 8 h); three on daily hemodialysis (6 d, 1½ to 2½ h); and 10 on automated peritoneal dialysis. All had urea kinetic studies and values for single pool Kt/V (Sp Kt/V), standard weekly Kt/V (Std Kt/V), and protein equivalent of nitrogen appearance (nPNA; g/kg/d). C reactive protein (CRP; mg/L) and thyroid stimulating hormone (TSH; mIU/L) were measured as factors known to influence cystatin C.Results: There was no correlation between cystatin C and Sp Kt/V, but there was a significant inverse linear correlation with Std Kt/V and there were significant differences between treatment modalities in cystatin C levels and in Std Kt/V. The estimation of cystatin C was reliable and stable over 3 to 6 wk and its levels uninfluenced by nPNA, CRP, or TSH.Conclusion: Serum cystatin C levels are influenced by the method and intensity of dialysis and may have a role in treatment adequacy monitoring.Serum creatinine is a widely used yet crude marker of GFR (GFR). The limitations of serum creatinine and creatinine clearance for estimation of GFR are well known (1). Creatinine concentration is affected by several factors that are independent of GFR, such as age, race, muscle mass, gender, medication use, and catabolic state (2). Serum cystatin C, a cystine protease inhibitor, is a low molecular weight protein (13.2 KD) produced at a constant rate by all nucleated cells (3). In the kidney, it is freely filtered and catabolized in the proximal tubule without being secreted (3). Studies suggest that cystatin C is a better marker of GFR than serum creatinine because of its independence from age and gender (4). Prediction equations have been derived from pediatric and adult patients to give an estimate of GFR from the serum cystatin C (5,6). Surprisingly there are few studies of serum cystatin C levels in dialysis patients. Its size (13.2 kDaltons) should make it dialyzable and a marker for “middle molecule” toxin removal. We, therefore, conducted a pilot study of serum cystatin C levels in such patients. A recent study by Delaney and colleagues suggested that serum cystatin C reflected predominantly renal not dialytic clearance in chronic renal failure patients on peritoneal dialysis (7). For this reason, we studied functionally anephric patients. We hypothesized that serum cystatin C levels would be related to markers of dialysis adequacy such as the standard weekly Kt/V urea (Std Kt/V) (8). To test this hypothesis, we studied patients treated by a variety of dialytic modalities that provided a range of values for Std Kt/V. Significant differences in Std Kt/V exist between conventional three times per week hemodialysis and daily or nightly hemodialysis (9). Std Kt/V can also be used to compare different treatment modalities (peritoneal versus hemodialysis) as well as different frequencies and treatment times (8). We studied patients encompassing all these treatment modalities.     

Correlates of urea kinetic modeling during hemodialysis in patients with acute renal failure

The current guidelines on dialysis adequacy in acute renal failure (ARF) are loosely defined and have been extrapolated from patients with end-stage renal disease. The objectives of this study were (1) to compare three methods of urea kinetic modeling measurement in patients with ARF receiving intermittent hemodialysis, (2) to compare prescribed to delivered dose of dialysis, and (3) to explore the factors that are associated with dialysis delivery. 'Single-pool' urea kinetic modeling was assessed by the Ureakin) software and the second-generation equation which uses a logarithmic estimate of spKt/V. 'Equilibrated' Kt/V (eKt/V) was calculated using the rate adjustment equation. The prescribed dose was derived using the manufacturer's specifications of the dialyzer clearance, prescribed time, actual delivered blood and dialysate flow, and estimates of volume of urea distribution. A total of 78 consecutive spKt/V measurements were obtained in 24 patients. The mean urea reduction ratio was 51 +/- 1%. The delivered spKt/V was significantly lower than that prescribed (0.87 +/- 0.03 or 0.83 +/- 0.03 vs. 1.28 +/- 0.05; p = 0.0001). The equilibrated Kt/V was markedly lower than the delivered spKt/V (0.73 +/- 0.03 vs. 0.83 +/- 0.03; p = 0.0001). Univariate analyses demonstrated that female gender, low body mass index, low predialysis weight, use of cellulose acetate dialyzers, and increased prescribed time were associated with increased odds of prescribed spKt/V > or =1.2. Similarly, old age, increased delivered time, and high cytokine production were associated with increased odds of delivered spKt/V > or =1.2. In summary, while the impact of delivered intermittent hemodialysis on the survival of patients with ARF remains to be determined, these results indicate that dialysis delivery is suboptimal in ARF, and empiric dosing should strongly consider factors related to lean body mass, including age and gender.     

Patient and technique survival in continuous ambulatory peritoneal dialysis (CAPD) with a basic three 2-liter daily exchanges: a 12- year single center experience in the pre-urea kinetics era

Continuous ambulatory peritoneal dialysis (CAPD) is the prevailing mode of renal replacement therapy in Hong Kong and the routine practice is three 2 L daily exchanges with four exchanges reserved for patients with ultrafiltration problems or clinically inadequate dialysis. In our hospital, Tung Wah Hospital, adequacy of dialysis assessment by urea kinetics was conducted after 1993 and adjustment of dialysis regime according to Kt/V was made only after 1995. This study represented the survival data of CAPD patients in our center before the urea kinetics era. From 1983 to 1994, we have accepted 569 patients into our CAPD program with a mean age ±SD of 47.8 ±15.4 and incidence of diabetes of 17.9%. The overall patient survival rates were 92%, 56% and 26% at 1, 5 and 10 years respectively. The corresponding technique survival rates were 97%, 86% and 60%. A cross-sectional analysis of the CAPD population from 1993 to 1994 showed that only 5% of patients were on four 2 L exchanges and the mean Kt/V was 1.76 ±0.35 and creatinine clearance 58.1 ±23.2 L/week/1.73 m². The patient and technique survival rates were comparable to western centers with a higher mean Kt/V and creatinine clearance. Our data showed that favorable clinical outcome can be achieved with three 2 L daily exchange regime in Chinese patients. This indicates different Kt/V standards may exist for different racial populations.     

腹膜透析治疗充分性评估与影响因素干预

腹膜透析(PD)充分性是PD患者预后的关键因素,目前国内外常用的小分子溶质清除指标为每周尿素清除指数(Kt/V)。Kt/V已经由既往指南的＞2.0,降低到≥1.7即可。除了小分子溶质清除外,容量平衡、营养状态、临床症状等也是透析充分性的评估指标。因此,PD充分性评估既有小分子溶质的清除,也包括其他综合性因素。影响透析充分性的因素中,残余肾功能、腹膜转运特性为主要因素,应予以足够重视并定期监测。     

Monitoring parameters of dialysis dose

In order to deliver a specific dialysis dose (Kt/V) to all patients, their product Kt (urea clearance K multiplied by dialysis time t) should be individually adjusted according to total body water (V) of each patient. With dialysis time being fixed in most centres for organisational reasons, such individualization can be accomplished by individually set blood flow (QB). For a given t, the value of QB also defines the magnitude of the cumulative blood volume (VB = QB*t), i.e. the volume of blood perfused through the dialyser during the whole dialysis time. VB is displayed by every contemporary dialysis machine but not used. The aim of this work was to derive an easy to use approach to QB individualization based on patient's body weight and dialysis time to obtain a desired Kt/V value which would also be easy to check after dialysis by looking at the obtained VB value. Statistically significant correlation was found between the QB-based Kt/V estimation and Kt/V determined by the other two methods demonstrating practical feasibility of the novel approach. Kt/V values obtained with the QB prescribed according to patient's body weight tended to be better in females and patients with higher body mass index.     

Incremental peritoneal dialysis - yes

The incremental modality at the start of peritoneal dialysis (Incr-DP) is implicit in the definition of adequacy, which is expressed as the sum of dialysis clearance and renal clearance.Theoretically, it is possible to demonstrate that with a glomerular filtration rate at the start of dialysis of 6 mL/min, the minimum Kt/V target of 1.70 indicated by the current guidelines is easily exceeded with both 2-exchange of CAPD (incremental CAPD) and APD of 3 or 4 weekly sessions (Incr-APD), with a daytime icodextrin dwell. The GSDP (Peritoneal Dialysis Study Group) census data suggest that Incr-DP favors the choice of peritoneal dialysis. Although limited to a few studies with a relatively small number of patients, data show that Incr- CAPD is associated with a better quality of life, the achievement of Kt/V targets, and satisfactory ultrafiltration. The clearance of medium molecules is equivalent in Incr-DP and full-dose PD as it depends on the duration of the dwell and not on the number of exchanges. The maintenance of body weight, protein intake and peritoneal permeability may be explained by the lower glucose load with Incr-DP. The preservation of residual renal function is similar to that recorded with full-dose PD, while the peritonitis rate seems to be lower. The favorable results reported in the literature and the indications of the most recent guidelines about the importance of reducing the exposure to glucose to a minimum and safeguarding the patient's quality of life in our opinion further justify the use of Incr-DP.     

Does dialysis therapy improve autonomic and peripheral nervous system abnormalities in chronic uraemia?

OBJECTIVES: Autonomic nervous system (ANS) dysfunction and peripheral neuropathy occur in patients with chronic renal insufficiency. Adequate renal replacement therapy should prevent development or correct these abnormalities. DESIGN AND SUBJECTS: We studied retrospectively ANS and peripheral neuropathy in 32 patients with chronic uraemia who received either haemodialysis (16) or peritoneal dialysis (16) therapy, and compared the observed dialysis efficiency with changes in neurological function. METHODS: Heart rate variability (HRV) time domain indices and peripheral sensory nerve conduction studies were followed for a mean of 2.9 years. The adequacy of haemodialysis (HD) efficiency was estimated by Kt/V, an index of fractional urea clearance. Adequacy of continuous ambulatory peritoneal dialysis (CAPD) was estimated on the basis of the patient's wellbeing and nutritional status as excellent, satisfactory or poor. Based on observed changes in HRV time domain measures, the observations were divided in three subgroups: improved, unchanged or deteriorated. RESULTS: The peripheral sensory nerve conduction studies were abnormal in 38% of the patients and did not change significantly during the study. Improvement in HRV time domain measures occurred in HD patients with mean Kt/V > 1.20 or in CAPD patients with satisfactory or excellent response to dialysis treatment. Values of Kt/V < 0.85 in HD patients were associated with progressive deterioration of autonomic neuropathy. Diabetic patients (n = 4) differed from others as their HRV was grossly abnormal and did not improve. CONCLUSIONS: The adequacy of haemodialysis is a predictor of improvement of cardiac autonomic nervous function in chronic uraemia. The same trend of improvement was seen also in CAPD patients.     

Treatment time and ultrafiltration rate are more important in dialysis prescription than small molecule clearance

Chronic hemodialysis sessions, as developed in Seattle in the 1960s, were long procedures with minimal intra- and interdialytic symptoms. Over the next three decades, dialysis duration was shorten to 4, 3, even 2 h in thrice weekly schedules. This method spread rapidly, particularly in the United States, after the National Cooperative Dialysis Study suggested that the time of dialysis is of minor importance as long as urea clearance multiplied by dialysis time and scaled to total body water (Kt/V(urea)) equals 0.95-1.0. This number was later increased to 1.3, but the assumption that hemodialysis time is of minimal importance remained unchanged. However, Kt/V(urea) measures only the removal of low molecular weight substances and does not consider the removal of larger molecules. Nor does it correlate with the other important function of hemodialysis, namely ultrafiltration. Rapid ultrafiltration is associated with cramps, nausea, vomiting, headache, fatigue, hypotensive episodes during dialysis, and hangover after dialysis; patients remain fluid overloaded with subsequent poor blood pressure control leading to left ventricular hypertrophy, diastolic dysfunction, and high cardiovascular mortality. Kt/V(urea) should be abandoned as a measure of dialysis quality. The formula suggests that it is possible to decrease t as long as K is proportionately increased, but this is not true. Time of dialysis should be adjusted in such a way that patients would not suffer from symptoms related to rapid ultrafiltration, would not have other uremic symptoms and most patients would have blood pressure controlled without antihypertensive drugs.     

残余肾功能状态对腹膜透析效能的影响

目的:前瞻性观察终末期肾衰(ESRF)患者在腹膜透析(PD)治疗后残余肾功能(RRF)对透析效能及相关临床指标之间的影响。方法:所有患者按残余肾小球滤过率(rGFR)水平将其分为A组(GFR0~2ml/min)、B组(GFR2·1~4ml/min)和C组(GFR>4ml/min)。每3个月进行一次临床随访,全面评估患者的全身情况及透析状态,包括血压、身高、体重、体重指数(BMI)、尿量(UV)、残余肾肌酐清除率(Ccr)、每周总尿素氮表现率(Kt/Vtotal)、每周肌酐总清除率(WCcrtotal)、蛋白氮呈现率(nPNA)、残余肾尿素及Ccr。对比观察不同RRF状态患者透析状况和部分临床及生化指标变化。尿量<100ml/d或Ccr<1·0ml/min视为无尿。结果:三组不同残肾状态患者Kt/vtotal和Ccr分别为1·75±0·35、2·07±0·54、2·46±0·50和53·4±11·2、66·6±11·2、97·6±22·1(L/Wks),各组之间差异非常显著(P<0·001)。三组不同残余肾Kt/v和Ccr分别占总体kt/v的12·4%、27%、45·7%及总体Ccr的18·3%、47·3%和65·3%,三组间相比差异亦显著(P<0·01)。此外,三组间高血压发生率、心胸比例及左心室肥厚(LVH)亦存在一定差异,C组心脏增大的病例明显低于A、B两组。RRF状态与透析效能呈正相关。本组患者除2例在透析治疗时即无尿,128例患者中有31例(24·2%)发生无尿,其中原发病为血管炎综合征及糖尿病肾病各占4例和7例,其无尿发生率分别占本病种的66·7%及25·9%;另20例无尿患者为肾小球肾炎或其它疾病,占此类疾病的20·6%。此外,发生无尿患者中有5例(16·1%)透析时尿量<300ml/d。结论:PD患者的残余肾仍然是清除体内代谢产物的重要途径,同时也影响血压及心血管系统并发症。     

The role of hematocrit in efficiency of dialysis

To test the role of hematocrit (Hct), particularly when in the nearly normal range, on efficiency of dialysis, we analyzed the urea kinetics for 36 metabolically and hematologically stable patients on regular dialysis treatment and for 7 patients from this group before and after 3 months of treatment with human recombinant erythropoietin (rHuEPO). The volume of distribution of urea (V), the dialyzer clearance (Kd) and Kt/V were plotted against Hct. Hct showed a significant inverse correlation with Kd (r = 0.479, p = 0.003) and Kt/V (r = 0.572, p = 0.0002). Further division of the patients into groups with respect to Hct showed that the lowest Kt/V values were in the group with Hct greater than or equal to 37%. In the patients treated with rHuEPO, Hct rose from 18 +/- 1 to 35 +/- 5% (p less than 0.0001), and Kt/V decreased from 1.22 +/- 0.21 to 1.09 +/- 0.18 (p = 0.037). We conclude that Hct exerts a negative influence on efficiency of dialysis as evaluated by Kt/V. This is important for patients with normal or nearly normal Hct levels as well as for patients treated with rHuEPO, for whom normalization of Hct is pursued.     

Lower Serum Albumin Level Is Associated With an Increased Risk for Loss of Residual Kidney Function in Patients Receiving Peritoneal Dialysis

Preserving residual kidney function (RKF) is important in the management of patients on peritoneal dialysis. However, few studies have examined the association between serum albumin level and the risk of RKF loss. We prospectively recruited 104 patients who began peritoneal dialysis treatment at our hospital between 2006 and 2016. The primary outcome was complete RKF loss, defined as urine volume < 100 mL/day. Serum albumin level at baseline was the main exposure. During a median observation period of 24 months, 33 patients developed RKF loss. A Cox proportional hazards model showed that hypoalbuminemia was associated with an increased risk of RKF, even after adjustments for potential confounding factors. Multivariable‐adjusted linear regression analysis also showed that hypoalbuminemia was associated with greater rates of decline in 24‐h urine volume and in renal Kt/V urea. Our findings suggest that hypoalbuminemia is associated with an increased risk of RKF loss in patients with peritoneal dialysis.     

Evaluation of pre- and postdilutional on-line hemodiafiltration adequacy by partial dialysate quantification and on-line urea monitor.

On-line highflux hemodiafiltration (HDF) is a clinically interesting and effective mode of renal replacement therapy, which offers the possibility to obtain an increased removal of both small and large solutes. The fundamental role of urea kinetic monitoring to assess dialysis adequacy in conventional hemodialysis has been widely studied. Both direct measurement of the urea removed by the modified direct dialysate quantitation (mDDQ) based on partial dialysate collection (PDC) and dialysate-based urea kinetic modeling (DUKM) using urea monitor have been advocated. The validity of this assessment tool in the patients with on-line HDF remained unclear. The aims of this investigation were (1) to compare the delivered Kt/V, urea mass removal (UMR), solute removal index (SRI) and normalized protein catabolic rate (nPCR) between pre- and postdilutional high-flux HDF; (2) to verify and compare the efficiency of pre- and postdilutional HDF using DUKM with on-line dialysate urea sensor, and mDDQ with partial dialysate collection. During both mode of HDF, the paired analysis urea removed and Kt/V showed no significant difference. Using mDDQ, mean values for predilutional mode were as follows: Kt/V 1.53 +/- 0.01 UMR, 16.8 +/- 0.3 g/session; urea clearance 178 +/- 18 ml/min; SRI 75.5 +/- 7.7%; urea distribution volume (V) 28.3 +/- 1.2 liters; nPCR 1.34 +/- 0.18 g/kg/day; on the other hand, mean values for postdilutional mode were Kt/V 1.58 +/- 0.01; UMR 17.10 +/- 0.28 g/session; urea clearance 184 +/- 21 ml/min; SRI 77.2 +/- 3.5%; urea distribution volume, 27.8 +/- 1.5 liters; nPCR 1.34 +/- 0.19 g/kg/day. The mean value of urea generation rate was 5.82 +/- 1.12 mg/min during HDF. Our results showed that dialysis adequacy was achieved with both high-volume predilutional HDF and postdilutional HDF. These two modes of HDF provided similar and adequate small solute clearance. In addition, we found that on-line analysis of urea kinetics is a reliable tool for quantifying and assuring delivery of adequate dialysis.