Search

Patients with chronic kidney disease (CKD) are at higher cardiovascular risk than the general population. Cardiovascular diseases, vascular calcification among them, are the leading cause of death in these patients. Factors influencing vascular calcification are oxidative stress, inflammation, and accumulation of uremic toxins during CKD. Uric acid is a cardiorenal toxin that accumulates in the case of kidney malfunction. The primary therapy for replacing kidney function and removing toxins from end-stage renal disease patients is hemodialysis. Effective removal of toxins can be estimated by blood or dialysate lab analysis or optical monitoring. In this study, the authors tested a miniaturized optical sensor for monitoring uric acid levels and removal for the first time in a more extensive clinical study, including Hemodialysis (HD) and Post-dilutional online hemodiafiltration (HDF) procedures with different settings in Tallinn, Estonia. The results (Mean±SD, Lab vs. Sensor) of the uric acid concentration 57.20±34.05 vs. 57.22±33.09 µmol/L, reduction ratio 68.72±10.91 vs. 67.89±12.48 %, and total removed amount 7.00±2.10 vs. 7.33±2.29 mmol did not differ significantly from the values obtained from the clinical laboratory (p<0.05).Clinical Relevance-During this study, a miniaturized optical sensor was tested for the first time in the clinic in different dialysis settings. The results confirm that the sensor is reliable for regularly monitoring cardiorenal toxin uric acid removal during hemodialysis.

Optical online methods are used to monitor the haemodialysis treatment efficiency of end stage kidney disease (ESKD) patients. The aim of this study was to analyse the effect of the administration of UV-absorbing drugs, such as paracetamol (Par), on the accuracy of optical monitoring the removal of uremic toxins uric acid (UA) and indoxyl sulfate (IS) during standard haemodialysis (HD) and haemodiafiltration (HDF) treatments. Nine patients received Par in daily dosages 1−4 g for 30 sessions. For 137 sessions, in 36 patients the total daily dosage of UV-absorbing drugs was less than 500 mg, and for 6 sessions 3 patients received additional UV-absorbing drugs. Par administration slightly affected the accuracy of optically assessed removal of UA expressed as bias between optically and laboratory-assessed reduction ratios (RR) during HD but not HDF employing UV absorbance of spent dialysate (p < 0.05) at 295 nm wavelength with the strongest correlation between the concentration of UA and absorbance. Corresponding removal of IS based on fluorescence at Ex280/Em400 nm during HD and HDF was not affected. Administration of UV-absorbing drugs may in some settings influence the accuracy of optical assessments in spent dialysate of the removal of uremic solutes during haemodialysis treatment of ESKD patients.

Optical monitoring of spent dialysate has been used to estimate the removal of water-soluble low molecular weight as well as protein-bound uremic toxins from the blood of end stage kidney disease (ESKD) patients. The aim of this work was to develop an optical method to estimate the removal of β2-microglobulin (β2M), a marker of middle molecule (MM) uremic toxins, during hemodialysis (HD) treatment. Ultraviolet (UV) and fluorescence spectra of dialysate samples were recorded from 88 dialysis sessions of 22 ESKD patients, receiving four different settings of dialysis treatments. Stepwise regression was used to obtain the best model for the assessment of β2M concentration in the spent dialysate. The correlation coefficient 0.958 and an accuracy of 0.000 ± 0.304 mg/L was achieved between laboratory and optically estimated β2M concentrations in spent dialysate for the entire cohort. Optically and laboratory estimated reduction ratio (RR) and total removed solute (TRS) of β2M were not statistically different ( p > 0.35). Dialytic elimination of MM uremic toxin β2M can be followed optically during dialysis treatment of ESKD patients. The main contributors to the optical signal of the MM fraction in the spent dialysate were provisionally identified as tryptophan (Trp) in small peptides and proteins, and advanced glycation end-products.

Tryptophan is an essential dietary amino acid that originates uremic toxins that contribute to end-stage kidney disease (ESKD) patient outcomes. We evaluated serum levels and removal during haemodialysis and haemodiafiltration of tryptophan and tryptophan-derived uremic toxins, indoxyl sulfate (IS) and indole acetic acid (IAA), in ESKD patients in different dialysis treatment settings. This prospective multicentre study in four European dialysis centres enrolled 78 patients with ESKD. Blood and spent dialysate samples obtained during dialysis were analysed with high-performance liquid chromatography to assess uremic solutes, their reduction ratio (RR) and total removed solute (TRS). Mean free serum tryptophan and IS concentrations increased, and concentration of IAA decreased over pre-dialysis levels (67%, 49%, -0.8%, respectively) during the first hour of dialysis. While mean serum total urea, IS and IAA concentrations decreased during dialysis (-72%, -39%, -43%, respectively), serum tryptophan levels increased, resulting in negative RR (-8%) towards the end of the dialysis session ( p < 0.001), despite remarkable Trp losses in dialysate. RR and TRS values based on serum (total, free) and dialysate solute concentrations were lower for conventional low-flux dialysis ( p < 0.001). High-efficiency haemodiafiltration resulted in 80% higher Trp losses than conventional low-flux dialysis, despite similar neutral Trp RR values. In conclusion, serum Trp concentrations and RR behave differently from uremic solutes IS, IAA and urea and Trp RR did not reflect dialysis Trp losses. Conventional low-flux dialysis may not adequately clear Trp-related uremic toxins while high efficiency haemodiafiltration increased Trp losses.

Aim: In this work we estimated the contribution of the fluorescence of 4-pyridoxic acid (4-PA) to the total fluorescence of spent dialysate with the aim of evaluating the on-line monitoring of removal of this vitamin B-6 metabolite from the blood of patients with end-stage renal disease (ESRD)., Methods: Spectrofluorometric analysis of spent dialysate, collected from hemodialysis and hemodiafiltration sessions of 10 patients receiving regularly pyridoxine injections after dialysis treatment, was performed in the range of Ex/Em 220-500 nm. 4-PA in dialysate samples was identified and quantified using HPLC with fluorescent and MS/MS detection., Results: Averaged HPLC chromatogram of spent dialysate had many peaks in the wavelength region of Ex320/Em430 nm where 4-PA was the highest peak with contribution of 42.2±17.0% at the beginning and 47.7±18.0% in the end of the dialysis. High correlation (R = 0.88-0.95) between 4-PA concentration and fluorescence intensity of spent dialysate was found in the region of Ex310-330/Em415-500 nm, respectively., Conclusion: 4-PA elimination from the blood of ESRD patients can be potentially followed using monitoring of the fluorescence of the spent dialysate during dialysis treatments., Competing Interests: The authors declare that they have no conflict of interest.

Purpose: The aim of the study was to explore the possibility of assessing lean body mass (LBM) based on UV absorbance measurements in spent dialysate., Methods: 9 patients on chronic three-times-a-week HD (4 female, 5 male, mean age 58.8 ± 8.6 years) were studied. Blood and spent dialysate samples were collected for 3 consecutive hemodialysis (HD) sessions from every patient. A double-beam spectrophotometer was used for the determination of UV absorbance in the collected spent dialysate samples. Dual-energy x-ray absorptiometry (DXA) scans were performed on an interdialytic day. LBM was calculated based on creatinine concentration in blood (LBMblood) and UV absorbance in spent dialysate (LBMa) and assessed by DXA (LBMDXA). Also, in vitro experiments were carried out to investigate the effect of tissue hydration on DXA measurements., Results: Although LBMa was slightly lower compared to LBMblood, the estimates based on UV absorbance in spent dialysate presented greater accuracy and precision compared to LBMDXA. The significant difference between LBMblood and LBMDXA was with high probability caused by the altered tissue hydration of HD patents., Conclusions: In summary, the results show that it is possible to asses LBM based on UV absorbance in spent dialysate.

Background: Early patient referral correlates with improved patient survival on dialysis. We examine whether early referral and a planned first dialysis affect quality of life (QoL)., Methods: All patients commencing dialysis in nine centres in seven European countries between 1 July 1998 and 31 October 1999 were recruited., Definitions: early referral=followed by a nephrologist >1 month before first dialysis (<1 month=late referral); planned=early referral and previous serum creatinine >300 micro mol/l and non-urgent first dialysis (early referral and no creatinine >300 micro mol/l or urgent first dialysis=unplanned). QoL was measured at 8 weeks using a visual analogue scale (VAS) and Short Form 36 (SF-36)., Results: VAS was significantly higher in early referral patients [mean (SD) 58.4 (20) vs 50.4 (19), P=0.005], particularly if the first dialysis was planned [60.7 (20) vs 54.2 (20), P=0.03]. Planned patients also had higher SF-36 mental summary scores [45.4 (12) vs 39.7 (11), P=0.003], role emotional scores [58.0 (43) vs 30.9 (38), P=0.003], and mental health scores [63.7 (24) vs 54.6 (22), P=0.01] than unplanned patients. Adjusting for centre and other confounding variables showed that having a planned first dialysis had an independent effect on QoL (VAS, and the SF-36's mental summary score, physical functioning, role physical, general health, role emotional and mental health). Early referral had no independent effect on QoL. Socio-economic status had an important positive effect on physical QoL., Conclusions: While the effect of early referral to a nephrologist on QoL appeared centre dependent, a smooth transition onto dialysis was associated with significantly better early QoL, independent of other variables.

Introduction: The epidemiology of end-stage renal disease (ESRD) and renal replacement therapy (RRT) is under continuous evolution all over the world. Of particular interest is the development of RRT in the countries of the former Soviet bloc which underwent great political and socio-economical changes in the last decade. We report here the epidemiological analysis of ESRD and RRT in the three Baltic countries: Lithuania, Estonia, Latvia. Subjects and methods. This epidemiological report is based on data from centre questionnaires which were collected from 1996 onwards, with a response rate of 98-99%., Results: The prevalence/incidence of RRT patients in 1999 were 213/99.5 p.m.p. in Lithuania, 186/45.5 p.m.p. in Estonia and 172/55.8 p.m.p. in Latvia. Haemodialysis (HD) was the most common RRT modality in Lithuania (60% of prevalent patients), but not in Estonia (29%), while in Latvia it was nearly as common as renal transplantation (45 and 46%, respectively). Home HD was not performed. The proportion treated by peritoneal dialysis (PD) was very low in Lithuania (4% of RRT patients), while the percentage was higher in Latvia (9%) and Estonia (20.4%). The percentage of patients on RRT treated by renal transplantation was high throughout, representing the main modality of treatment in Estonia (50.5% of RRT prevalent patients, 94 p.m.p.) and in Latvia (46%, 79 p.m.p.) and being high in Lithuania (36%, 77 p.m.p.). The main renal diseases leading to ESRD were glomerulonephritis, pyelonephritis and diabetes., Conclusion: The epidemiology of RRT in the Baltic countries is undergoing rapid changes. Transplantation has reached an impressive level. A high percentage of RRT patients live with a functioning graft.