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Recent studies have shown that microRNA-16-5p ( miR-16-5p ) plays a crucial role in the pathological mechanism of vascular calcification. Nevertheless, the expression profile of miR-16-5p in maintenance hemodialysis (MHD) patients who are predisposed to vascular calcification remains unknown. This study aims to investigate the potential associations between calcification risk and serum miR-16-5p expression among MHD patients. This cross-sectional study involved 132 MHD patients from the Dialysis Center of Beijing Friendship Hospital between 1 January 2019 and 31 December 2020. The degree of calcification in MHD patients was assessed using the Abdominal aortic calcification (AAC) score, and miR-16-5p expression was quantified using quantitative real-time polymerase chain reaction (qRT-PCR) with the 2 -ΔΔCT method. Statistical analyses, including spearman correlation, linear regression and logistic regression analysis were used to explore the associations between laboratory parameters and AAC score. Calcifications were observed in 79(59.80%) patients. The linear regression showed a one-quartile decrease in miR-16-5p expression led to a significant increase in the AAC score by 5.336 (95% CI: 2.670-10.662, p  = 0.000). Multivariate logistic regression analyses revealed that decreased miR-16-5p expression, reduced serum urea nitrogen, elevated white blood cell count, and longer dialysis vintage were significantly associated with an increased incidence of vascular calcification. The Area Under the Curve (AUC) of the Receiver Operating Characteristic (ROC) of the miR-16-5p-based logistic regression model was 0.842 (95% CI: 0.771-0.913, p  = 0.000). There was an independent association between miR-16-5p expression and calcification degree. Lower miR-16-5p expression levels seem to be a potential risk factor of vascular calcification in MHD patients.

Hemodialysis (HD) leads to cognitive impairment; however, the pathophysiology of maintenance HD remains unclear. This study aimed to investigate the longitudinal alterations in gray matter volume (GMV) and cerebral blood flow (CBF) in patients on HD at follow-up compared with baseline, examine the alterations in functional connectivity (FC) by defining co-changed brain regions as seed points, and investigate the correlation between the co-changed brain regions and neuropsychological test scores. Twenty-seven patients with HD and 30 healthy controls were enrolled in this study. All participants underwent high-resolution T1-weighted imaging, arterial spin labeling, and functional MR imaging to measure GMV, CBF, and FC. The patients on HD were assessed at baseline and 3 years subsequently. The right and left medial superior frontal gyrus (SFGmed.L) exhibited significantly lower GMV and CBF in patients on HD at follow-up compared with baseline and lower FC between the SFGmed.L and left middle temporal gyrus (MTG.L). FC between the SFGmed.L and MTG.L was positively correlated with neuropsychological test scores in the HD group at follow-up. Reduced GMV and CBF may result in decreased FC between the SFGmed.L and MTG.L, which may be associated with cognitive impairment in patients on maintenance HD. Our findings provide unique insights into the pathological mechanisms of patients on maintenance HD with cognitive impairment., Competing Interests: Declarations. Ethical approval: The study has been approved by the Ethics Committee of Beijing Friendship Hospital, Capital Medical University. The study was conducted following the Declaration of Helsinki. Consent to participate: Informed consent was obtained from all study participants. Legally Authorized Representatives of illiterate participants provided informed consent for the study. Consent to publication: All the authors agreed to publish this article. Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background & Aims: Sarcopenia is frequent in hemodialysis patients and associated with an increased likelihood of adverse outcomes. Early identification of the risk of sarcopenia and effective intervention are of great importance for dialysis patients. However, little research has been carried out on potential biomarkers of sarcopenia in hemodialysis patients. The aim of this study was to investigate whether serum carnitine or acylcarnitine levels are biomarkers of sarcopenia in hemodialysis patients, and whether these are prognostic factors for occurrence of complications., Methods: This prospective clinical pilot study enrolled patients (n = 259) who were treated in the Blood Purification Center from May 2021 to July 2022, all participants were followed-up for 1- year. Serum carnintine and acylcarnitine (AC) were measured using our previously reported targeted liquid chromatography tandem mass spectrometry (LC-MS/MS) method. The correlations between carnitine or acylcarnitine levels with sarcopenia and prognosis in patients were analysed., Results: The C0 (Free carnitine, FC) and total carnitine (TC) levels were significantly lower in the sarcopenia group than in the nonsarcopenia group [nonsarcopenia vs. sarcopenia: 20.97 (16.96, 25.83) vs. 17.77 (14.30, 22.78); p = 0.002] and [nonsarcopenia vs. sarcopenia: 30.12 (24.76, 36.62) vs. 26.03 (21.30, 32.01); p = 0.003]. Besides, significant difference between the groups were noted in low free carnitine (C0 < 20 μmol/L) patients (nonsarcopenia vs. sarcopenia: 72 (42.4%) vs. 56 (62.9%); p = 0.002) and high C2/C0 ratio (>0.4) patients (nonsarcopenia vs. sarcopenia: 36 (21.2%) vs. 30 (33.7%); p = 0.028). By multivariable analysis, the disturbed CM defined as C0 deficient and/or C2/C0 carnitine ratio abnormal rise was independently and significantly correlated with the prevalence of sarcopenia after adjusting for some confounding factors, such as age, gender and dialysis duration (P values for trend <0.05). Hemodialysis patients with sarcopenia [OR: 3.214 (1.307,7.904)] and disturbed CM [OR: 3.217 (1.112,9.305)] both had a 3-fold increased risk of falling and fracture after one year follow up. In addition, age and sarcopenia [OR: 2.883 (1.321, 6.289)] were independently and positively associated with incidence of Cardio- and cerebro-vascular events., Conclusion: Disturbed carnitine metabolism is independently correlated with sarcopenia and prognosis in patients with hemodialysis. Serum carnitine level and C0/C2 ratio has the potential to be a simple, objective, and quick test for sarcopenia assessment whether such an intervention should be carried out for dialysis patients., Competing Interests: Conflict of interest There are no conflicts of interest/competing interests to declare., (Copyright © 2024 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

Background: Phosphates, similar to urea, are small molecular substances that can be cleared during dialysis. Dialytic phosphate reduction rate (PRR) may, to some extent, be related to the relative amount of phosphates cleared during dialysis. However, few studies have evaluated the associations between PRR and mortality in maintenance hemodialysis (MHD) patients. In this study, we investigated the association between PRR and clinical outcomes in MHD patients., Methods: This was a retrospective, matched case-control study. Data were collected from the Beijing Hemodialysis Quality Control and Improvement Center. Patients were divided into four groups according to PRR quartile. Age, sex, and diabetes were matched between the groups. The primary outcome was all-cause death, and the secondary outcome was cardiocerebrovascular death., Results: The study cohort comprised 4063 patients who were divided into four groups according to the PRR quartile: group PRR 1 (< 48.35%), group PRR 2 (48.35% - 54.14%), group PRR 3 (54.14% - 59.14%), and group PRR 4 (≥ 59.14%). We enrolled 2172 patients (543 in each study group) by case-control matching. The all-cause death rates were as follows: group PRR 1 : 22.5% (122/543), group PRR 2 : 20.1% (109/543), group PRR 3 : 19.3% (105/543), and group PRR 4 : 19.3% (105/543). No significant differences in all-cause and cardiocerebrovascular death rates according to the Kaplan-Meier survival curves were found between the groups (log-rank test, P > 0.05). Multivariable Cox regression analysis revealed no significant differences in all-cause and cardiocerebrovascular death rates between the four groups (P = 0.461; adjusted hazard ratio, 0.99; 95% confidence interval, 0.97 - 1.02 versus P = 0.068; adjusted hazard ratio, 0.99; 95% confidence interval, 0.97 - 1.00, respectively)., Conclusions: Dialytic PRR was not significantly associated with all-cause death and cardiocerebrovascular death in MHD patients., (© 2023. The Author(s).)

Background: Patients undergoing hemodialysis experience inflammation, which is associated with a higher risk of mortality. The lymphocyte-to-C reactive protein ratio (LCR) is a novel marker of inflammation that has been shown to predict mortality in patients with malignant cancer. However, the utility of LCR has not been evaluated in patients undergoing hemodialysis., Methods: We performed a multi-center cohort study of 3,856 patients who underwent hemodialysis as part of the Beijing Hemodialysis Quality Control and Improvement Project between 1 January 2012 and December 2019. The relationship between LCR and all-cause mortality was assessed using a restricted cubic spline model and a multivariate Cox regression model. An outcome-oriented method was used to determine the most appropriate cut-off value of LCR. Subgroup analysis was also performed to evaluate the relationships of LCR with key parameters., Results: Of the 3,856 enrolled patients, 1,581 (41%) were female, and their median age was 62 (53, 73) years. Over a median follow-up period of 75.1 months, 1,129 deaths occurred. The mortality rate for the patients after 60 months was 38.1% (95% confidence interval (CI) 36%-40.1%), resulting in a rate of 93.41 events per 1,000 patient-years. LCR showed an L-shaped dose-response relationship with all-cause mortality. The optimal cut-off point for LCR as a predictor of mortality in hemodialysis patients was 1513.1. An LCR of ≥1513.1 could independently predict mortality (hazard ratio 0.75, 95% CI 0.66-0.85, P<0.001)., Conclusions: Baseline LCR was found to be an independent prognostic biomarker in patients undergoing hemodialysis. Implying that it should be a useful means of improving patient prognosis and judging the timing of appropriate interventions in routine clinical practice., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Chen, Guo, Diao, Huang and Liu.)

Introduction: Patients' session-to-session variation has been shown to influence outcomes, making critical the monitoring of dialysis dose in each session. The aim of this study was to detect the intra-patient variability of blood single pool Kt/V as measured from pre-post dialysis blood urea and from the online tool Adimea ® , which measures the ultraviolet absorbance of spent dialyzate., Methods: This open, one-armed, prospective non-interventional study, evaluates patients on bicarbonate hemodialysis or/and on hemodiafiltration. Dialysis was performed with B. Braun Dialog+ machines equipped with Adimea ® . In the course of the prospective observation, online monitoring with Adimea ® in each session was established without the target warning function being activated. A sample size of 97 patients was estimated., Results: A total of 120 patients were enrolled in six centers in China (mean age 51.5 ± 12.2 years, 86.7% males, 24.2% diabetics). All had an AV-fistula. The proportion of patients with blood Kt/V < 1.20 at baseline was 48.3%. During follow-up with Adimea ® , the subgroup with Kt/V > 1.20 at baseline remains at the same adequacy level for more than 90% of the patients. Those with a Kt/V < 1.20 at baseline, showed a significant increase of Kt/V to 60% of the patients reaching the adequacy level >1.20. The coefficient of variation for spKt/V as evaluated by Adimea ® was 9.6 ± 3.4%, not significantly different from the 9.6 ± 8.6% as blood Kt/V taken at the same time., Conclusion: Online monitoring of dialysis dose by Adimea ® improves and maintains dialysis adequacy. Implementing online monitoring by Adimea into daily practice moves the quality of dialysis patient care a significant step forward.

Background: Hemodialysis is the main approach for renal replacement therapy in patients with end-stage renal disease (ESRD) in China. The timing of dialysis initiation is one of the key factors influencing patient survival and prognosis. Over the past decade, the relationship between the timing of dialysis initiation and mortality has remained unclear in patients with ESRD in China., Methods: Patients who commenced maintenance hemodialysis from 2009 to 2014 from 24 hemodialysis centers in Mainland China were enrolled in the study (n = 1,674). Patients were divided into 2 groups based on the year they started hemodialysis (patients who started hemodialysis from 2009 to 2011, and patients who started hemodialysis from 2012 to 2014). Analysis of the yearly change in the estimated glomerular filtration rate (eGFR) at the initiation of dialysis was performed for the 2 groups. Meanwhile, the patients were divided into 3 groups based on their eGFR at the initiation of dialysis (<4, 4-8, and >8 mL/min/1.73 m2). For these 3 groups, the relationship between the eGFR at the start of dialysis and mortality were analyzed., Results: The average eGFRs were 5.68 and 5.94 mL/min/1.73 m2 for 2009-2011 and 2012-2014, respectively. Compared with the 2009-2011 group, the proportion of patients with diabetes in 2012-2014 increased from 26.7 to 37.7%. The prognosis of patients with different eGFRs at the start of dialysis was analyzed using Kaplan-Meier survival curves. After adjusting for confounding factors through a Cox regression model, no significant difference was demonstrated among the 3 groups (<4 mL/min/1.73 m2 was used as the reference, in comparison with 4-8 mL/min/1.73 m2 [p = 0.681] and >8 mL/min/1.73 m2 [p = 0.403])., Conclusion: In Mainland China, the eGFR at the start of dialysis did not change significantly over time from 2008 to 2014 and had no association with the mortality of patients with ESRD., (© 2020 The Author(s) Published by S. Karger AG, Basel.)

Introduction: Starting dialysis early or late both result in a low quality of life and a poor prognosis in patients undergoing haemodialysis. However, there remains no consensus on the optimal timing of dialysis initiation, mainly because of a lack of suitable methods to assess variations in dialysis initiation time. We have established a novel equation named DIFE (Dialysis Initiation based on Fuzzy-mathematics Equation) through a retrospective, multicentre clinical cohort study in China to determine the most suitable timing of dialysis initiation. The predictors of the DIFE include nine biochemical markers and clinical variables that together influence dialysis initiation. To externally validate the clinical accuracy of DIFE, we designed the assessment of DIFE (ADIFE) study as a prospective, open-label, multicentre, randomised controlled trial to assess the clinical outcomes among patients who initiate dialysis in an optimal start dialysis group and a late-start dialysis group, based on DIFE., Methods and Analysis: A total of 388 enrolled patients with end-stage renal disease will be randomised 1:1 to the optimal start dialysis group, with a DIFE value between 30 and 35, or the late-start dialysis group, with a DIFE value less than 30, using the Randomization and Trial Supply Management system. Participants will be assessed for changes in signs and symptoms, dialysis mode and parameters, biochemical and inflammatory markers, Subjective Global Assessment, Kidney Disease Quality of Life Short Form, Cognitive Assessment, medical costs, adverse events and concomitant medication at baseline, predialysis visiting stage and postdialysis visiting stage, every 12-24 weeks. The following data will be recorded on standardised online electronic case report forms. The primary endpoint is 3-year all-cause mortality. The secondary endpoints include non-fatal cerebrocardiovascular events, annual hospitalisation rate, quality of life, medical costs and haemodialysis related complications., Ethics and Dissemination: Ethical approval was obtained from the Ethics Committee of the First Affiliated Hospital of Dalian Medical University China (registration no: YJ-KY-2017-119) and the ethics committees of all participating centres. The final results of the ADIFE trial will be presented to the study sponsor, clinical researchers and the patient and public involvement reference group. Findings will be disseminated through peer-reviewed journals, Clinical Practice Guidelines and at scientific meetings., Trial Registration Number: ClinicalTrial.gov. Registry (NCT03385902); pre-results., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Severe secondary hyperparathyroidism (SHPT) is a serious problem in patients undergoing hemodialysis. The efficacy and safety of microwave ablation (MWA), a minimally invasive treatment, for severe SHPT are as yet unclear. To clarify the role of MWA, we administered it to patients with severe SHPT and assessed its efficacy and safety. This was a prospective, single-center, single-arm, clinical trial. We enrolled patients with severe SHPT attending our hemodialysis center who met the inclusion and exclusion criteria. We then assessed primary outcome measures (serum concentrations of intact parathyroid hormone) and secondary outcome measures (serum concentrations of calcium and phosphorus). Twenty-six patients were enrolled in this study, 10 of whom (38.46%) were responsive to MWA and 16 (61.54%) of whom were not. The main complication was hypocalcemia (10 cases, 38.46%), which had occurred in all cases by one week after administration of MWA. Responding patients with hypocalcemia all achieved normal serum calcium concentrations within seven months and non-responding patients within three months. There were no changes in serum phosphorus concentrations after MWA in either responders or non-responders. Microwave ablation is relatively ineffective in patients with severe SHPT undergoing maintaining hemodialysis and should not be the initial therapy in such cases.

Background: It has been argued that the benefits of reducing sodium loading may be offset by increased activation of the renin-angiotensin-aldosterone system (RAAS) and sympathetic nervous system. This study aimed to investigate the long-term effects of an increase in dialysis sodium removal on circulating RAAS and sympathetic system in hypertensive hemodialysis (HD) patients with "normal" post-HD volume status., Methods: Thirty hypertensive HD patients were enrolled in this pilot trial. After one month period of dialysis with standard dialysate sodium of 138 mmol/L, the patients were followed up for a four months period with dialysate sodium set at 136 mmol/L, without changes in instructions regarding dietary sodium control. During the period of study, the dry weight was adjusted monthly under the guidance of bioimpedance spectroscopy to maintain post-HD volume status in a steady state; 44-hour ambulatory blood pressure, plasma renin, angiotensin II (Ang II), aldosterone, and norepinephrine (NE) were measured., Results: After four months of HD with low dialysate sodium of 136 mmol/L, 44-hour systolic and diastolic blood pressures (BPs) were significantly lower (-10 and -6 mmHg), in the absence of changes in antihypertensive medications. No significant changes were observed in plasma renin, Ang II, aldosterone, and NE concentrations. The post-HD volume parameters were kept constant., Conclusion: Mildly increasing dialysis sodium removal over 4 months can significantly improve BP control and does not activate circulating RAAS and sympathetic nervous system in hypertensive HD patients.

Purpose: To investigate the effect of no water removal (NWR) on preservation of residual renal function (RRF) in new hemodialysis (HD) patients., Methods: Fifty-six patients with a daily urine volume ≥ 1,000 mL were included. Patients were randomized to different fluid management groups of NWR or water removal (WR) for 6 months. If predialysis BP was >150/90 mmHg, patients could take antihypertensive drugs. The primary endpoints included death, cardio-cerebral vascular disease, refractory hypertension, and edema or an auxiliary examination indicating obvious fluid retention. The secondary endpoint was oliguria. A daily urine volume, 24-h urine creatinine clearance, the defined daily dose (DDD) index of antihypertensive drugs, erythropoietin resistance index, cardiothoracic ratio, and left ventricular mass index (LVMI) were recorded., Results: Eight patients in the NWR group reached the primary endpoints. Nine patients in the WR group reached the secondary endpoint. At the end of the study, patients in the NWR group had more increased systemic blood pressure (9.0 ± 8.3 vs. -2.4 ± 2.0 mmHg, p < 0.001), DDD index (1.2 ± 1.02 vs. -0.9 ± 0.51, p < 0.001), daily urine volume (164 ± 351 vs. -726 ± 342 mL, p < 0.001), cardiothoracic ratio (0.02 ± 0.04 vs. -0.03 ± 0.03, p < 0.001), LVMI (9.6 ± 17.0 vs. -12.0 ± 21.4 g/m(2), p < 0.001), and less decreased urine creatinine clearance (-1.0 ± 0.4 vs. -2.0 ± 1.0, p < 0.001), compared with those patients in the WR group., Conclusions: Preservation of RRF by NWR is warranted in new HD patients, but is not appropriate for all patients.

Background: The raw annual mortality rate reported in Chinese patients on maintenance hemodialysis (MHD) was around 10% between 2005 to 2010, and it was around 20% in the US as reported by the United States Renal Data System (USRDS). Our hypothesis was that the large survival difference was caused by differences in race and practice pattern between nations in addition to differences in patient characteristics., Methods: Annual mortality in Beijing prevalent MHD patients per year in 2007, 2008, 2009 and 2010 was reported and relative risks of death were compared with the corresponding mortality of USRDS prevalent MHD patients (in whites, African-Americans and Asian-Americans) after age, gender and primary cause of end-stage renal disease (ESRD) were adjusted. A total of 11 675 MHD patients from 104 dialysis facilities under control of Beijing Blood Purification Quality Control and Improvement Center (BJBPQCIC) from 31 December 2006 to 31 December 2010 were included. A total of 1 937 819 MHD patients (only white, African-American and Asian-American were eligible for inclusion) were subtracted from the USRDS No-60-Day prevalent dataset from the year 2004 to 2009, using the RenDER system. Raw annual mortality for each race was reported as a number per 1000 MHD patients at risk for each year. Age, gender and primary cause of ESRD, adjusted annual mortality and relative risk race of death were reported comparing the Beijing patients and each race of the USRDS., Results: The raw annual mortality for the Beijing cohort increased gradually from 47.8 per 1000 patient-years in 2007 to 76.8 in 2010. The raw annual mortality for the white cohort in 2007 was 250.7 per 1000 patient-years, and gradually decreased to 236.3 in 2009. The raw annual mortality for African-Americans (167.8 and 156.7 per 1000 patient-years in 2007 and 2009, respectively) was much lower than that for whites. The annual mortality for Asian-Americans was slightly lower than that for African-Americans. After adjustment, Beijing MHD still had a survival benefit compared with each of the examined USRDS race. The annual mortality rates were 99.4, 80.6 and 94.3 per 1000 patient-years when adjusted to whites, African-Americans and Asian-Americans, respectively, in cohort 2009., Conclusions: The annual mortality for the Beijing MHD patients was lower than that for their USRDS counterparts, and this difference existed after baseline demographics were adjusted. This survival difference between the Beijing and the USRDS MHD cohorts could be attributed to differences in race or practice pattern. More studies are needed to validate our hypothesis.

Background: Mineral and bone disorder (MBD) in patients with chronic kidney disease is associated with increased morbidity and mortality. Studies regarding the status of MBD treatment in developing countries, especially in Chinese dialysis patients are extremely limited., Methods: A cross-sectional study of 1711 haemodialysis (HD) patients and 363 peritoneal dialysis (PD) patients were enrolled. Parameters related to MBD, including serum phosphorus (P), calcium (Ca), intact parathyroid hormone (iPTH) were analyzed. The achievement of MBD targets was compared with the results from the Dialysis Outcomes and Practice Study (DOPPS) 3 and DOPPS 4. Factors associated with hyperphosphatemia were examined., Results: Total 2074 dialysis patients from 28 hospitals were involved in this study. Only 38.5%, 39.6% and 26.6% of them met the Kidney Disease Outcomes Quality Initiative (K/DOQI) defined targets for serum P, Ca and iPTH levels. Serum P and Ca levels were statistically higher (P < 0.05) in the HD patients compared with those of PD patients, which was (6.3 ± 2.1) mg/dL vs (5.7 ± 2.0) mg/dL and (9.3 ± 1.1) mg/dL vs (9.2 ± 1.1) mg/dL, respectively. Serum iPTH level were statistically higher in the PD patients compared with those of HD patients (P = 0.03). The percentage of patients reached the K/DOQI targets for P (37.6% vs 49.8% vs 54.5%, P < 0.01), Ca (38.6% vs 50.4% vs 56.0%, P < 0.01) and iPTH (26.5% vs 31.4% vs 32.1%, P < 0.01) were lower among HD patients, compared with the data from DOPPS 3 and DOPPS 4. The percentage of patients with serum phosphorus level above 5.5 mg/dL was 57.4% in HD patients and 47.4% in PD patients. Age, dialysis patterns and region of residency were independently associated with hyperphosphatemia., Conclusions: Status of MBD is sub-optimal among Chinese patients receiving dialysis. The issue of hyperphosphatemia is prominent and needs further attention.

Residual renal function (RRF) is of paramount importance for hemodialysis (HD) adequacy, morbidity, and mortality. Some studies have shown that overhydration is beneficial for preservation of RRF, but it can also increase the probability of adverse events such as hypertension and heart failure in HD patients. To determine the optimal amount of dehydration, we performed HD with limited water removal in HD patients. Eighteen HD patients included in this self-controlled study underwent HD with limited water removal. Water removal volume was determined by a previous volume as follows. Total water removal volume was divided into levels: ≤3.0, 3.0-9.0, and >9.0 L per week. Water removal was performed to obtain dry weight in the last dialysis, and was performed three times with a ratio of 1:1:2 and 2:2:3, respectively. Urine volume, endogenous creatinine clearance rate, Kt/V, hemoglobin, and serum albumin were recorded before and after the study at 3, 6, 9, and 12 months. The follow-up period was 12 months. Ten patients withdrew from the study because of adverse events including hypertension (n = 3), heart failure (n = 3), angina (n = 1), polycystic kidney rupture (n = 1), obvious edema (n = 1), and one patient had too much interdialytic weight gain to continue. As a result, we stopped this study after 1 month. Our data suggest that the preservation of RRF with limited water removal in HD patients must be interpreted with caution.