Peritoneal Equilibration Test Reference Values Using a 3.86% Glucose Solution During the First Year of Peritoneal Dialysis: Results of a Multicenter Study of a Large Patient Population.

BACKGROUND: The original peritoneal equilibration test (PET) was used to classify peritoneal dialysis (PD) patients using a 2.27% glucose solution. It has since been suggested that a 3.86% glucose solution be used because this provides better information about ultrafiltration (UF) capacity and the sodium (Na) sieving of the peritoneal membrane. OBJECTIVE: The aim of this study was to determine reference values for a PET using a 3.86% glucose solution (PET-3.86%). METHODS: We evaluated the PET-3.86% in a large population of incident PD patients attending 27 Italian dialysis centers. RESULTS: We evaluated the results of 758 PET-3.86% in 758 incident PD patients (1 test per patient). The mean duration of PD was 5 ± 3 months. The ratio of the concentrations of creatinine in dialysate/plasma (D/PCreat) was 0.73 ± 0.1 (median 0.74). The ratio between the concentrations of glucose at the end/beginning of the test (D/D0) was 0.25 ± 0.08 (median 0.24). Ultrafiltration uncorrected and corrected for bag overfill was respectively 776 ± 295 mL (median 781 mL) and 675 ± 308 mL (median 689 mL). Sodium sieving was 8.4 ± 3.8 mmol/L (median 8.0 mmol/L). CONCLUSION: The results of the study provide PET-3.86% reference values for the beginning of PD that can be used to classify PD patients into transport classes and monitor them over time.

Ionic conductivity of peritoneal dialysate: a new, easy and fast method of assessing peritoneal membrane function in patients undergoing peritoneal dialysis.

BACKGROUND: Peritoneal membrane function can be assessed using the peritoneal equilibration test (PET) and similar tests, but these are almost always complicated to use, require a considerable amount of working time and their results cannot always be easily interpreted. Ionic conductivity is a measure of the ability of an electrolyte solution to conduct electricity. We tested the hypothesis that the ionic conductivity of peritoneal dialysate can be used to evaluate peritoneal membrane function in peritoneal dialysis patients. METHODS: We measured the ionic conductivity and classic biochemical parameters of peritoneal dialysate in 69 patients during a modified PET and compared their ability to evaluate peritoneal membrane function and to diagnose ultrafiltration failure (UFF). RESULTS: Ionic conductivity was correlated well with classical parameters of peritoneal transport as glucose reabsorption of glucose (D/D0: r(2) = 0.62, P < 0.0001) and creatinine transport (D/PCreat: r(2) = 0.72, P < 0.0001). Twelve patients (17%) experienced UFF and, in them, the ionic conductivity area under the receiver-operating characteristic curve was 0.91 (95% confidence interval: 0.81-0.96) with sensitivity of 1.00 and specificity of 0.84 at a cut-off value of 12.75 mS/cm. CONCLUSIONS: These findings indicate that the ionic conductivity of peritoneal dialysate can be used as a new screening tool to evaluate peritoneal membrane function.

[Trend in PD in non-pediatric public centers in Italy: results of the 2010 GSDP-SIN census and comparison with the 2008 and 2005 censuses]. / Andamento della DP in Italia nei centri pubblici non pediatrici: Risultati del censimento GSDP-SIN 2010 e confronto con i censimenti 2008 e 2005.

The 2010 Italian Society of Nephrology Peritoneal Dialysis Study Group (GSPD-SIN) census (Cs-10) involved the 224 Centers performing PD in Italy. PD was used as 1st treatment in 23.3% (1429/4695) of pts (Cs-08:22.8%; Cs-05:24.2%), with 53.4% of them using CAPD. The use of incremental CAPD increased in Cs-10 (Cs-10:35.3%; Cs-08:25.7%; Cs-05:13.6%; p<0.0001). The number of prevalent pts was 4,222 (Cs-10:16.6%; Cs-08:16.6%; Cs-05:16.8%; p=NS), 45.7% of whom were on CAPD; 24.4% (Cs-08:21.8%; p<0.05) required assistance (family member:80.6%; caregiver:12.6%; nurse: 3.0%; RSA:3.4%). In Cs-10 the PD out rate (1,354 pts, of whom ep/100pt-yrs for drop-out: 12.4; death: 12.9; Tx: 7.5) was not different to previous years. The peritonitis rate was 0.30 ep/yr/pt, 18.5% of which with negative culture. There were 44 episodes of EPS in the period 2009-10 (0.53 ep/100yrs); while in the previous 5-year period there were 146 (0.70 ep/100pt-yrs). PET is performed by 98% of the centers, mostly using 2.27% (70.5%). Home visits are carried out by 59.1% of the centers. If regular (8.9% of the centers), they are associated with fewer ep/mth of peritonitis (61.2 vs 38.8) and lower drop-out (8.6 vs 12.8 ep/100 pt/yr - p<0.05) Cs-10 confirms the good results PD is having in the Centers that use it. Incremental CAPD and assisted PD are increasing. EPS remains a rare event. Standard PET is the most frequently-used evaluation of the peritoneal membrane. Though home visits are associated with lower peritonitis and drop-out rates, they are carried out regularly by a minority of the Centers.

A load volume suitable for reaching dialysis adequacy targets in anuric patients on 4-exchange CAPD.

INTRODUCTION: Continuous ambulatory peritoneal dialysis (CAPD) depuration indexes are targeted to get a minimum total weekly peritoneal urea clearance (Kt/V) of 1.70 and creatinine clearance/1.73 m(2) (pCrCL) of 50 l. In anuric patients these targets are difficult to achieve. Since dialysis volumes (load, VOL(in); drain, VOL(out)) are the main determinants of peritoneal clearances (pCLs), we aimed to estimate the minimum volumes required to fulfill these targets in anuric patients. METHODS: Sixty-nine CAPD anuric patients from eight dialysis units were observed retrospectively. Demographic data, dialysis schedule, VOLs and depuration indexes were recorded. The relationship between normalized VOLs and pCLs was estimated by linear regression analysis as a whole (95 % confidence interval of the fit) and stratified by tertiles of body weight (BW) and surface area (BSA). RESULTS: Mean weekly pKt/V was 1.89 ± 0.29, pCrCL 52.9 ± 8.0, VOL(in) 32.9 ± 5.3 ml/kg and VOL(out) 37.4 ± 6.7 ml/kg exchange. VOL(in) and VOL(out) correlated with depuration indexes only if normalized. A VOL(in) of 28.5 ml/kg exchange (27.0-30.0) was associated with a pKt/V of 1.70, and a VOL(in) of 29.5 (26.5-31.5) with a pCrCL of 50 l, with a VOL(out) of 31.7 ml/kg (29.5-33.5) and 32.4 (27.2-35.5), respectively. Smaller patients needed a lower normalized VOL(in)/exchange to obtain pKt/V = 1.70 (1st vs. 2nd vs. 3rd BW tertiles: 28.3 vs. 28.9 vs. 29.0 ml/kg; BSA tertiles: 1,696 vs. 1,935 vs. 2,086 ml/1.73). CONCLUSIONS: In CAPD anuric patients VOL(in) prescription could be tailored to body mass to reach the minimum depuration target. Normalized VOL(in) might be prescribed in slightly higher doses (from 27 to 30 ml/kg exchange) for patients with higher body mass.

The peritoneal dialysis catheter.

The results obtained from the positioning and management of the catheter for peritoneal dialysis depend on the techniques used, but also and above all, on the experience of the practitioners. A comparison between practitioners may help to change their convictions, as well as to further improve results, in the interests of patient welfare. This is the aim of these Best Practice Guidelines..

Peritoneal ultrafiltration in patients with advanced decompensated heart failure.

The aim of the Best Practice guidelines on peritoneal ultrafiltration (UF) in patients with treatment-resistant advanced decompensated heart failure (TR-AHDF) is to achieve a common approach to the management of decompensated heart failure in those situations in which all conventional treatment options have been unsuccessful, and to stimulate a closer cooperation between nephrologists and cardiologists. The standardization of the case series of different centers would allow a better definition of the results published in the literature, without which they are nothing more than anecdotes. TR-AHDF is characterized by the persistence of severe symptoms even when all possible pharmacological and surgical options have been exhausted. These patients are often treated with methods that allow extracorporeal UF - slow continuous ultrafiltration (SCUF) and continuous renal replacement therapy (CRRT) - which have to be performed in hospital facilities. Peritoneal ultrafiltration (PUF) can be considered a treatment option in patients with TR-AHDF when, despite the fact that all treatment options have been used, patients meet the following criteria: • stage D decompensated heart failure (ACC/AHA classification); • INTERMACS level 4 decompensated heart failure; • INTERMACS frequent flyer profile; • chronic renal failure (estimated glomerular filtration rate <50 ml/min per 1.73 m2: KDOQI classification stage 3 chronic kidney disease); • no obvious contraindications to peritoneal UF. PUF treatment modes are derived from the treatment regimens proposed by various authors to obtain systemic UF in patients with severe decompensated heart failure, using manual and automated incremental peritoneal dialysis involving various glucose concentrations in addition to the single icodextrin exchange. These guidelines also identify a minimum set of tests and procedures for the follow-up phase, to be supplemented, according to the center's resources and policy, with other tests that are less routine or more complex also from a logistic/organizational standpoint, emphasizing the need for the patient's clinical and treatment program to involve both the nephrologist and the cardiologist. The pathophysiological aspects of a deterioration in kidney function in patients with decompensated heart failure are also considered, and the results of PUF in patients with decompensated heart failure reported in the various case series are reviewed.

Encapsulating peritoneal sclerosis.

The purpose of this best practice is to briefly define what has now been accepted regarding encapsulating peritoneal sclerosis (EPS), highlighting the latest developments and outlining future lines of research. The medical therapy that can be proposed (to be discussed individually, verifying the individual features of the patient) appears to include steroids, tamoxifen, and sirolimus or everolimus, with blood levels maintained at reference values for post-transplantation therapy. In view of the high incidence of relapse also in responders, it appears appropriate to continue therapy for prolonged periods, at least for 6 months. Moreover, a surgical assessment is indicated, especially for patients with intestinal symptoms including subocclusion status. To date the prevention of EPS is an unresolved issue. The recommended measures include the accurate prevention and best treatment of acute peritonitis, the use of biocompatible dialysis fluids (there is no consensus on their exact definition) and the monitoring of ultrafiltration characteristics and peritoneal membrane transport. Other recommended measures are the extensive use of renin-angiotensin- aldosterone axis inhibitors for the treatment of arterial hypertension in PD and the exclusion of beta- blockers. Other suggested strategies are tamoxifen prophylaxis in cases at risk and to adopt personalized immunosuppressive protocols for patients with PD who undergo renal transplantation.

Incidence of renal replacement therapy in Veneto for 2008, 2009 and 2010.

This section of the report of the Veneto Dialysis and Transplantation Registry (VDTR) provides data on the incidence of patients receiving renal replacement therapy (RRT) in the region from 2008 to 2010. Its purpose is to provide health authorities with the information they need to plan the delivery of RRT in Veneto. Data were obtained from the VDTR, defining incident patients according to the recommendations of the Italian Dialysis and Transplantation Registry. The incidence rate was calculated per million population (pmp). Variability by province and treatment center was studied by applying multilevel modeling methods. An age-period-cohort model was used to forecast the incidence rate of RRT over the years to come. The incidence of patients on RRT was 114.23 pmp in 2008, 120.15 pmp in 2009 and 107.08 pmp in 2010. The patients' median age at the time of starting RRT was 70.5 in 2008, 68.7 in 2009 and 69.5 in 2010. During these 3 years, 66.3% of patients were male, and 33.7% were female. Incidence rates were not uniformly distributed between the provinces in the region, but were significantly higher in 2. The incidence rate of patients needing RRT seems likely to remain stable in the future, until 2015 at least. Renal vascular disease was the primary cause of end-stage renal disease (ESRD), followed closely by diabetes, while the proportion due to primary glomerulonephritis has gradually decreased. Initial dialysis modality was hemodialysis (HD) for 78% of patients, while about 20% started RRT on peritoneal dialysis (PD), and a negligible proportion had a preemptive kidney transplantation. About 35% patients began dialysis with a temporary vascular catheter; this percentage remained fairly constant until 2010. The incidence of RRT in Veneto is one of the lowest in Italy and remained substantially stable over the period 1998-2010, despite the population of patients with ESRD becoming older and more severely ill. This finding could mean a heavier burden on the welfare system in the future.

Prevalence of renal replacement therapy in Veneto for 2008, 2009 and 2010.

The aim of this section is to provide descriptive data for end-stage renal disease (ESRD) in the Veneto Region (Italy). Data were obtained from the Veneto Dialysis and Transplantation Registry (VDTR). Patients were considered to be prevalent renal replacement therapy (RRT) patients if alive on 31 December of each year examined. Prevalence is expressed per million population (pmp). The trend for prevalence of each treatment in the period examined was estimated by random effects longitudinal logistic regression. Prevalence of RRT in Veneto in the years 2008, 2009 and 2010 was 888, 923 and 950 pmp, respectively. The prevalence of RRT patients by treatment modality showed a slight increase for hemodialysis, notable stability for peritoneal dialysis and a more pronounced increase for transplantation. Every year, about 10% of peritoneal dialysis patients shifted to hemodialysis, and 12% received a transplant. The transition probability from hemodialysis to peritoneal dialysis was negligible, and less than 5% of hemodialysis patients received a transplant. The probability of returning to hemodialysis after having received a transplant was less than 2% a year. Bicarbonate hemodialysis slowly increased from 1998 to 2010, both in percentage and in prevalence per million population; conversely, hemodiafiltration (HDF) showed a mild but constant decrease. Automated peritoneal dialysis (APD), which was quantitatively almost negligible in 1998, reached the same level as continuous ambulatory peritoneal dialysis (CAPD) in 2010. The prevalence of patients undergoing living donor transplants almost doubled in the period 1998-2010. The increase of prevalence over time was not proportional for the 3 modalities of RRT: hemodialysis prevalence grew slowly, peritoneal dialysis prevalence remained stable, and renal transplant prevalence quickly increased.

Mortality in the Veneto population on renal replacement therapy.

This section reports survival rates for patients on renal replacement therapy (RRT). The data obtained from the Veneto Dialysis and Transplantation Registry (VDTR) cover the whole population in the region. Patients on RRT alive on 31 December of each year were assumed to be at risk of dying in the following year. Furthermore, time-to-event analysis was used to describe the complete history of patients from when they started RRT until they died, including transitions between the 3 main treatment modalities - hemodialysis (HD), peritoneal dialysis (PD) and renal transplantation. The cohort of patients starting RRT from 1998 to 2010 was followed up until 31 December 2010. Survival rates from the first treatment to death were calculated according to the life table method. Relative survival and excess mortality rates were estimated according to the Ederer II method. A multistate model was used to describe changes in a patient's condition (changes of treatment, or death) over time. Among prevalent patients on RRT, the annual risk of death was 10.65% in 2008, 9.35% in 2009 and 8.86% in 2010. The overall mortality rate was 12.5 per 100 patient-years (95% confidence interval [95% CI], 12.1-13.0). The 5-year relative survival was 59% (95% CI, 57%-60%), and at 10 years relative survival was 41% (95% CI, 39%-43%); the estimated excess mortality rate was very high at the start of RRT (18 per 100 patient-years) but gradually decreased after the second year. On multivariate analysis, excess mortality was associated with age and primary renal diseases. Less than 10% of patients starting on PD shifted to HD in the first year of RRT, and a considerable proportion received a transplant, amounting to 6% in the first year, and thereafter increasing steadily: at the end of the fifth year, 34% of patients starting RRT on PD had received a transplant. HD patients behaved differently: any shift to PD was negligible, and the patients receiving a transplant amounted to only 2% in the first year and about 16% by the end of the fifth year. Cumulative mortality among HD patients was particularly high (already 18% at 1 year, and 70% at 10 years) by comparison with those on PD (8% at 1 year, 54% at 10 years). Although mortality on RRT is not particularly high in Veneto by comparison with countries other than Italy, this result is mainly due to an increasing number of patients receiving transplants, which makes them a favorably selected population. The mortality rate was high among those on HD, particularly in the first year. Our population on RRT is rather heterogeneous, and a description of the outcomes based only on the whole population may be misleading.

[Incremental peritoneal dialysis - no]. / Dialisi peritoneale incrementale - no.

The incremental approach to peritoneal dialysis provides reduced dialytic purification by an intermittent schedule maintaining the total solute clearance above the minimal targets, even if they have not been validated as adequacy targets for intermittent treatments. The early initiation of peritoneal dialysis (GFR >8 mL/min 1.73 m²) has been demonstrated not to be useful to improve patient survival. Standard initiation of dialysis (GFR 5-7 mL/min 1.73 m²) using the incremental modality implies a loss of dialysis clearance that is likely to have an effect on-often asymptomatic-cardiovascular disease. There is no scientific evidence that incremental peritoneal dialysis helps to preserve residual renal function or the peritoneal membrane nor that it reduces the peritonitis rate or complications due to uremia. The central role of the extent of residual renal function regarding the prescription of incremental peritoneal dialysis and the usual procedures for its assessment set the stage for possible underdialysis, even for short periods.

Comparison between creatinine-based equations for estimating total creatinine clearance in peritoneal dialysis: a multicentre study.

BACKGROUND: It is crucial to assess the adequacy of peritoneal dialysis (PD) because of its influence on patient outcome. Collecting dialysate and urine for 24 h can be rather troublesome, so a simple and inexpensive alternative method for rapidly evaluating adequacy in PD would be very useful. Our study aimed to assess the performance of 12 different creatinine (Cr)-based equations commonly used to estimate GFR in predicting total Cr clearance (totCrCL) in PD. METHODS: Four Italian dialysis centres enrolled 355 PD patients with 2916 fluid collections. To rank the equations, their accuracy (median absolute percentage error, MAPE), precision (root mean square error, RMSE), agreement (k statistics), sensitivity and specificity (area under ROC curves, AUC, where x = 1 - specificity and y = sensitivity) were calculated with reference to the measured totCrCL. RESULTS: The Gates, Virga and 4-MDRD equations showed the best global performance as concerns accuracy (MAPE = 14.1, 16.3, 15.9% respectively), precision (RMSE = 13.2, 13.3, 13.4), agreement (k = 0.425, 0.440, 0.375), sensitivity and specificity (AUC = 0.825, 0.826, 0.820), while the Cockcroft-Gault formula revealed a rather poor reliability. CONCLUSIONS: Fluid collection remains the gold standard for assessing PD adequacy. Our study ascertained how 12 Cr-based equations performed in estimating totCrCL in PD patients with a view to enabling the most accurate and precise among them to be chosen for use in approximately assessing totCrCL.

A new equation for estimating renal function using age, body weight and serum creatinine.

BACKGROUND: Many formulas have been developed to estimate glomerular filtration rate (GFR). The aim of our study was to propose a new, more reliable equation. METHODS: The study considered 530 subjects (training sample) with M/F 280/250, age 57.1 +/- 17.4, creatinine clearance (CrCl) 55.2 +/- 38.2 (range 2.1-144.0) for the development the new equation. A linear model was used to describe Cr production using serum Cr (sCr), age, and body weight (BW) as variables: (CrCl + b(4)) . sCr = b(1) - (b(2) . age) + (b(3) . BW) subsequently estimating parameter values by linear least squares, with CrCl as the dependent variable, and 1/sCr, age/sCr, BW/sCr as independent variables. CrCl = {[69.4 - (0.59 . age) + (0.79 . BW)]/sCr} - 3.0 (males) and {[57.3 - (0.37 . age) + (0.51 . BW)]/sCr} - 2.9 (females). A 229-patient renal failure validation sample with M/F 166/63, age 53.0 +/- 14.8, GFR 32.0 +/- 14.3 (range 4.3-69.8), assessed using iohexol Cl, was considered to compare the Cockcroft-Gault (C-G) and MDRD formulas with the new equation for estimating GFR. RESULTS: The mean % error in GFR estimated by the new equation (+2.3 +/- 28.3%) was better than with the C-G and MDRD formulas (+5.2 +/- 30.1% and -11.4 +/- 25.9%, respectively, p < 0.0005 and p < 0.0001), and so was the mean absolute % error, bordering on statistical significance (19.8 +/- 20.3 vs. 21.1 +/- 22.0 and 22.4 +/- 17.3, p = 0.08 and p < 0.005). The precision was also better (RMSE = 7.89 vs. 8.02 and 9.13). The Bland-Altman test showed no GFR over or underestimation trend (measured +/- predicted GFR/2 vs. % error, R2 = 0.001). CONCLUSIONS: The new equation appears to be at least as accurate as the C-G and MDRD formulas for estimating GFR.

Systolic and diastolic function in renal replacement therapy: a cross-sectional study.

BACKGROUND: Heart disease is the main cause of death among uremic patients (pts). Our study aimed to assess left ventricular (LV) systolic and diastolic function in all of our pts on renal replacement therapy (RRT), investigating any differences between hemodialysis (HD), peritoneal dialysis (PD) and transplantation (TX) pts. METHODS: All pts on RRT at our nephrology unit were enrolled in the study and evaluated once over a period of 6 months: 125 pts were studied: 61 pts on HD, 30 pts on PD and 34 TX pts. Systolic and diastolic function indexes were compared between HD, PD and TX pts. All comparisons were corrected for the effects of age, gender and time on treatment. RESULTS: HD pts suffered from worse systolic function, with a lower mean fractional shortening and ejection fraction (EF), than TX pts. Twenty percent of HD pts had an EF value <55%. PD pts showed worse diastolic function than TX pts and >80% of them suffered from pathological diastolic indexes. The proportion of hypertensive pts was TX 88.2%, PD 86.7% and HD 50.8%. The percentage of pts with LV hypertrophy (LVH) was TX 55.9%, PD 53.3% and HD 36.1%. CONCLUSIONS: TX pts had better systolic and diastolic function than HD and PD pts, despite having more hypertension and LVH.

Comparison of peritoneal equilibration test with 2.27% and 3.86% glucose dialysis solution.

BACKGROUND: The standard Peritoneal Equilibration Test (PET) uses a 2.27% glucose dialysis solution in peritoneal dialysis (PD). A more hypertonic solution (3.86%) has recently been proposed to obtain further information about ultrafiltration (UF). AIM: To compare results in terms of peritoneal solute transport (4h-dialysate-to-plasma ratio, 4h-D/P) between 2.27% and 3.86% PET. DESIGN: 23 patients on PD were randomized to form two groups, A and B. A 2.27% dextrose 2-L exchange was used in group A, followed on the same day by a 3.86% dextrose 2-L exchange, both with a 4-hour dwell (2.27% and 3.86% PET); in group B, the same treatment was administered in reverse. 4h-D/P of urea, creatinine and sodium at time 0, 60, 120 and 240 minutes and net UF were calculated for each PET and compared. RESULTS: No significant statistical differences were found for the usual peritoneal transport indexes, 4h-D/P of urea and creatinine, between 2.27% and 3.86% PET, which produced almost identical results. The creatinine 4h-D/P were 0.67+/-0.09 vs. 0.66+/-0.10 (p= NS) and the urea 4h-D/P 0.91+/-0.04 vs. 0.90+/-0.04 (p= NS). The sodium D/P was lower at all times during the 3.86% PET: D/P60= 0.92+/-0.05 vs. 0.88+/-0.03, D/P120= 0.91+/-0.02 vs. 0.87+/-0.03, D/P240= 0.92+/-0.02 vs. 0.88+/-0.04 (p< 0.0001). The net UF was 478 +/- 175 vs. 936 +/- 233 mL respectively (p< 0.0001). CONCLUSION: Our study suggests that a 3.86% PD solution could be used for PET instead of the 2.27% solution in order to assess peritoneal solute transport, as well as UF, while obtaining almost identical results as the 2.27% solution.

Sodium removal and sodium concentration during peritoneal dialysis: effects of three methods of sodium measurement.

BACKGROUND: Sodium removal (NaR) may have a major impact on the survival of peritoneal dialysis patients. The dialysate/plasma sodium concentration ratio (D/P(Na)) is an indirect index of transcellular water transport by aquaporin channels, and thus of ultrafiltration. Sodium concentration can be assessed by means of flame photometry (F), and direct (D-ISE) or indirect ion-selective electrodes (I-ISE), but these methods have different properties. I-ISE is being used increasingly in clinical laboratories. The aim of this study was to evaluate NaR and D/P(Na) using the three different measurement methods. METHODS: We performed peritoneal equilibration tests (PETs) in 44 peritoneal dialysis patients and calculated the NaR. We also calculated D/P(Na) during the test; plasma and dialysate sodium concentrations were measured by F, D-ISE and I-ISE. RESULTS: NaR was lower (P<0.001) with D-ISE (69+/-29 mmol) than with F (81+/-29 mmol) or I-ISE (79+/-28 mmol). D/P(Na) was also lower at baseline (0.92+/-0.02 vs 0.95+/-0.02 and 0.95+/-0.02; P<0.001), after 60 min (0.87+/-0.03 vs 0.90+/-0.03 and 0.90+/-0.03; P<0.001) and at the end of PET (0.88+/-0.04 vs 0.92+/-0.04 and 0.92+/-0.04; P<0.001) when measured by D-ISE in comparison with F and I-ISE, respectively. CONCLUSIONS: NaR and D/P(Na) were lower when measured by the D-ISE method compared with the F and I-ISE methods. NaR and D/P(Na) were similar when measured by F or I-ISE. I-ISE can be used reliably in the evaluation of NaR and D/P(Na) in everyday clinical practice of peritoneal dialysis.