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World Journal of Nephrology & Urology

Original Article

Volume 12, Number 1, July 2023, pages 1-7

Albumin Loss in Post-Dilution On-Line Hemodiafiltration Compared With Pre-Dilution On-Line Hemodiafiltration and Conventional Hemodialysis

Hemodiafiltration (HDF) has been established as the best method of dialysis for patients with end-stage renal disease. The attributed clearance it offers is the highest, both in the form of the pre- and post-dilution models. However, there are reports that the method has negative effects on patients, including loss of albumin during the session, but this has not yet been fully clarified in the literature.

The aim of our study was to determine the amount of albumin lost during a dialysis session, using a polyethersulfone filter with both pre-dilution and post-dilution HDF, and with conventional hemodialysis (HD), with filters of the same synthesis.

Ten patients were studied (seven males and three females), aged 48 - 85 years (mean ± standard deviation (SD): 65.5 ± 11, median age: 68.5 years). All had initially been on conventional HD for 10 - 450 months (145 ± 158) and subsequently on on-line HDF for at least 4 months (12.2 ± 7.08). Their primary diseases were glomerulonephritis (four), polycystic kidney disease (two), hypertensive nephrosclerosis (one), and unknown etiology (three). Six of them had a native arteriovenous anastomosis, three had a graft, and one had a double-lumen jugular vein dialysis catheter. Only three had residual renal function (24 h urine output > 400 mL/24 h in the day off dialysis), and the other seven had urine output of less than 150 mL/day (Table 1).

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Table 1. Age, Body Weight, Water Composition of Patient’s Body, Residual Urination, Duration of Dialysis Session, Months on Conventional Dialysis, and Months on On-Line HD

Patients with cancer, active infection, known cardiovascular disease, and unstable hemodynamic status during the dialysis sessions were excluded from the study.

At the mid-week session (Wednesday or Thursday), a blood sample was taken before the start of dialysis for analysis of serum urea and albumin levels. One hour after the end of the session (to allow for urea redistribution in the body), a blood sample was taken to determine the same parameters. All procedures were in accordance with the ethical standards of the Scientific Council of our Hospital.

Low molecular weight heparin (bemiparin) was used in all patients in doses of 2,500 - 3,500 IU/session, depending on their body weight. For all patients, the blood supply to the filter was 400 mL/min, with arterial aspiration pressure < 200 mm Hg [1] and the dialysate flow rate was 500 mL/min, as previously specified by others [2] (all HD machines used were the Nikkiso DBB EXA). The duration of the sessions for seven patients was 4 h, for two patients, it was 4 h and 15 min, and for one patient, it was 4 h and 45 min (Table 1).

Polyethersulfone-polynephron filters (Elisio 2.1 m² and 2.5 m² high-flux and 2.1 m² low-flux) were used. All patients underwent one post-dilution on-line HDF session with a filter surface area of 2.5 m² (group A) and a second session with a 2.1 m² surface area (group B), one pre-dilution HDF session with a 2.5 m² high-flux filter (group D) and one session of conventional HD with a low-flux filter of 2.1 m² (group C). The substitution volume used in the post-dilution was 25% of the blood pump (i.e., > 24 L/session), while in the pre-dilution, it was 50% of the blood pump (i.e., > 48 L), which was considerably greater than the body water of each of our patients. In our analysis of the results, the median value of transmembrane pressure (TMP) during the session was used (Table 1).

The entire ultrafiltrate was collected in a specially made volumetric barrel. At the end of the session, and after mixing the ultrafiltrate with an electric stirrer for 10 min, a sample was taken for the determination of urea and albumin levels.

The Abbott Alinity C analyser was used to determine the parameters studied. Urea was determined by an enzymatic method, while albumin was determined by a colorimetric method.

For the statistical analysis, the Student’s t-test and the paired t-test were used. Differences were considered significant when the significance level was P < 0.05.

Previously, as mentioned, all patients had been in a conventional HD program for 10 - 450 months (mean ± SD: 145 ± 158 months). Then, for another 4 - 24 months, they had been on on-line post-dilution HDF (mean ± SD: 12.2 ± 7.08 months). Before the start of the on-line HDF, their serum albumin levels were, on average, 42.1 ± 2.6 g/L (in nine > 40 g/L and in one 39 g/L). After 4 - 24 months on the new method (post-dilution on-line HDF), this had essentially not changed, since it was now on average 41.4 ± 2.8 g/L (in eight > 40 g/L, in one 37 g/L and in another one 39 g/L), a difference that was not statistically significant (P = NS) (Table 2).

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Table 2. Serum Albumin (Before and After Starting On-Line HDF), Dialysate Albumin During On-Line HDF and Conventional Hemodialysis and URR of Patients in Every Group

Albumin loss in group A was marginally significantly greater compared to albumin loss in group B (2.82 ± 1.19 vs. 1.94 ± 0.97 g/dialysis session, P = 0.05), but there was no difference in albumin loss between group A and group C (2.82 ± 1.19 vs. 2.36 ± 0.87 g/dialysis session, P = NS). However, the loss in group D was statistically significantly lower than that in all the other groups (A, B, C) ((A-D) 2.82 ± 1.19 vs. 1.75 ± 0.097 g/dialysis session, P < 0.01; (B-D) 1.94 ± 0.97 vs. 1.75 ± 0.097 g/dialysis session, P < 0.01; (C-D) 2.36 ± 0.87 vs. 1.75 ± 0.097 g/dialysis session, P < 0.03) (Table 2). TMP was significantly lower in group D compared to groups A (P < 0.0001) and B (P < 0.0001).

The urea reduction ratio (URR) in every case (groups A, B, C, D) was, on average, > 73.5% but, in fact, it was significantly lower in group C compared to groups A and B (Table 2).

The serum albumin concentration is the net result of its synthesis by the liver (about 12 g/24 h), its catabolism (about 4%/24 h) (which increases in inflammatory diseases) [3], its volume of distribution, its exchange between the intra- and extra-vascular space (70% of albumin is normally in the vascular space, which also applies to hemodialyzed patients), and losses from the body (via the digestive system, the kidneys or due to the dialysis filter). In our patients, the clearance was excellent, since the URR was > 73.5% in every model of dialysis used. Of course, in cases where there are reduced serum albumin levels, the most important role is played by its reduced synthesis. This is due to the inhibitory effect on the synthesis of albumin from acute phase response, which usually happens in infections, but also in other conditions (cancers, immune diseases, etc.).

The 1999 - 2010 NHANES study showed that 53% of patients with an estimated glomerular filtration rate < 60 mL/min/1.73 m² had serum albumin levels < 42 g/L [4]. The percentage will clearly be even lower in hemodialyzed patients compared to the general population. Indeed, the KDOQI guidelines recommend that serum albumin levels in hemodialyzed patients be maintained above 40 g/L [5]; however, the DOPPS data show that over 60% of hemodialyzed patients have serum albumin levels < 40 g/L [6]. Lowrie and Lew also reported mean serum albumin levels of 38 g/L in 12,000 cases [7]. Eriguchi et al (n = 36,757) found mean serum albumin levels of 35.7 ± 4.6 g/L [8]. Ye et al (n = 110,794) found mean serum albumin levels of 35 ± 5 g/L [9], while Kalantar-Zadeh et al (n = 58,058) reported mean serum albumin levels < 40 g/L in 72% of their patients, with 52% of them having serum albumin levels < 38 g/L [10]. Compared to the figures reported in these studies, almost all our patients had higher serum albumin levels and were within the desired level.

Basically, in hemodialyzed patients, the synthesis of albumin is related to its level in the plasma [11], which means that, in the absence of malnutrition or inflammation, patients maintain albumin levels within normal limits through an increase in its synthesis [12]. This is confirmed by data showing that in nephrotic patients, relative to the degree of albuminuria, the absolute rate of albumin synthesis increases by 7.7 g/1.73 m²/24 h (a 73% increase), compared to controls (i.e., patients: 18.2 ± 2 vs. controls: 10.5 ± 1 g/1.73 m²/24 h) [12].

Based on data in the literature, the question remains whether the reduction in serum albumin levels due to filter loss is harmful. It is not known whether the loss with on-line HDF has an impact on serum albumin levels or on patient survival [13]. This is because the main cause of hypoalbuminemia in hemodialyzed patients is the reduction in the rate of albumin synthesis and an increase in its catabolism due to the stimulation of the acute phase response [14] and not due to its loss. This may explain why we did not find a decrease in serum albumin levels in our patients after 4 - 24 months of HDF.

Albumin, on the other hand, is a protein binder for uremic toxins, so it could play a positive role in ameliorating the toxicity of uremia [15, 16]. Obviously, as more of it is removed with on-line HDF, the higher the molecular weight of the uremic toxins removed with dialysis. In other words, its loss may be beneficial, due to the significant removal of associated toxins, and also due to the loss of its oxidized form (that is, the form that has lost its antioxidant activity), as well as the end glycosylation products [17]. It is noted that this loss can promote the synthesis of new albumin that does have antioxidant properties [18].

There is a loss of albumin during the replacement of renal function, and as we found, the amount that is lost varies with the model of dialysis. High-flux membranes achieve better removal of medium- and high-molecular weight toxins [19], and several studies show that albumin loss during on-line HDF with high-flux membranes ranges from 1 to 3 g per session [20-22], consistent with our findings. Other researchers have argued that a weekly loss of < 12 g of albumin during dialysis sessions, due to the use of filters, appears to be of little risk [23]. This finding agrees with those of others who suggest that a “desirable loss of albumin in one session should be less than 4 g” [24]. At this level of loss, serum albumin levels are stable in patients on long-term on-line HDF [25], as our results confirmed. However, using these membranes, some researchers have found an initial increase in serum albumin levels [26]. After 6 months of dialysis with these filters, others have found an increase in serum albumin of 0.5 - 1.1 g/L [27].

As is to be expected, albumin loss by the convection treatment is greater, especially when using post-dilution on-line HDF (range 0.08 - 7.0 g/4 h of treatment) [23, 28-31]. In the literature, albumin loss in pre-dilution on-line HDF is generally less (range: 3.0 - 4.8 g/4 h session), due to the diluted albumin available for transport [29, 32-34], as we also noted.

Since HDF relies on convection, which is the driving force for the removal of small molecular weight proteins, the loss of albumin and larger uremic toxins is dependent on the TMP, and the greater the TMP, the greater the loss, particularly in comparison with conventional HD [17]. This difference can be seen in pre- and post-dilution: in post-dilution, the TMP is higher and therefore, the albumin loss is greater, as we also found in our study.

Convection treatments significantly increase the removal of middle molecular weight toxins, compared to diffusion treatments, especially when high TMPs are applied [28, 35, 36]. In fact, it was found that the loss of albumin was greater during the first 30 - 60 min of the session, due to the high TMP applied to the intact membrane [34, 37]. This loss is then limited by the creation of a secondary protein layer on the dialysis membrane, due to deposition of proteins such as fibrinogen.

Another parameter that plays a role in the removal of albumin through the filter is the surface area [38]. An increase in its area, as well as an increase in blood supply to the filter, has been associated with an increased loss of amino acids [39, 40], as we also found to be true for albumin when using blood flow to the filter of 400 mL/min with a filter surface area of either 2.5 or 2.1 m² (group A vs. group B, P = 0.05).

Inadequate dialysis clearance can lead to anorexia, with consequent malnutrition and hypoalbuminemia. That is, the synthesis of albumin depends on the severity of the uremia and therefore on the dialysis dose. This association has been confirmed by studies showing an improvement in serum albumin levels after increasing the dialysis dose [41]. We also found our on-line HDF patients had a mean URR > 73.5% (range 70.4-80.1%) with serum albumin in the normal range, although some others do not agree with these results [42].

Albumin loss during convection with high-flux membranes is generally reported to range from 0 to 2 g per 4 h dialysis session, depending on membrane synthesis and filter surface area [3, 39, 43-46]. Our results confirm these findings.

Regarding serum albumin levels, studies have shown that when switching from high permeability HD membranes to a corresponding permeability (high-flux) for post-dilution on-line HDF, there is a decrease in serum albumin [47, 48]. It is important to note, however, that although albumin loss increases in patients who are on on-line HDF, no deterioration in nutritional status was noted. Although albumin loss increases with this model of dialysis, when patients who had serum levels of 39.2 ± 3.3 g/L on conventional HD, changed to post-dilution on-line HDF, after 1 year their serum levels were 39.1 ± 2.98, after 2 years they were 39.5 ± 3.03, after 3 years they were 39.4 ± 2.97, and after 4 years they were 41.4 ± 2.55 g/L, thus showing no statistically significant difference. Thus, a small decrease in serum levels was found, compared to conventional HD [47], indicating that albumin levels on conventional HD correspond to those of patients on on-line HDF, results with which do not agree with those of other researchers [49].

Finally, a study that investigated the efficacy and safety of 19 filters concluded that thermal sterilization increased the permeability of the membrane pores to albumin, compared to sterilization with γ-radiation [50]. The polynephron filters are sterilized by γ-radiation and this may have played a role in the small amount of albumin removed during the session.

Comparing the two types of membrane (polynephron and polyethersulfone), researchers found that polynephron showed less albumin loss in post-dilution on-line HDF [33]. In fact, it was found that the average loss of albumin in the dialysate ranged from 1.8 ± 0.6 to 5.7 ± 2.1 g per session. In post-dilution, polynephron is associated with a lower loss of albumin, compared to polysulfone, while in general, albumin loss is greater in post-dilution with both membranes, as we also found [33].

The polynephron membrane has a thin capillary wall (30 µm) and a relatively large pore size (78 Å), aiming overall at better elimination of large molecules, without higher loss of albumin. Of course, not all large pore membranes can be considered the same, even when their size or the polymers from which they are made, are identical [51, 52]. However, others investigating the polynephron membrane found no loss of albumin in the dialysate (considering the possible hemoconcentration at the end of the dialysis session with post-dilution) [53].

Finally, elixone and polyethersulfone membranes have been compared for albumin loss in on-line HDF. It was found that the latter lost more albumin than elixone, and that when the substitution volume was greater, more albumin was lost [36].

The conclusion is that polynephron filters in on-line HDF lose more albumin in the post-dilution model, which increases further if their surface area increases, and also with an increase of TMP, but the serum albumin levels do not drop below the recommended levels. The URR achieved with these filters was very good in every model of treatment investigated in our study.

Acknowledgments

We thank our colleagues at the Renal Unit, “Dimokrition” Konstantinos Antonakakis and Emine Ibis, for their help in the collection, measurement, and sampling of the ultrafiltrate for each patient throughout the study period.

Financial Disclosure

The authors have no financial relationships relevant to this article to disclose.

Conflict of Interest

The authors have no conflict of interest relevant to this article to disclose.

Informed Consent

Written informed consent was obtained from the patient before the study.

Author Contributions

KSM designed the study, read the literature, and wrote the manuscript. IMK and PSP found the literature, selected the patients, and helped run the study. All authors reviewed and approved the final manuscript.

Data Availability

The data supporting the findings of this study are available from the corresponding author upon reasonable request.

1. Ashby D, Borman N, Burton J, Corbett R, Davenport A, Farrington K, Flowers K, et al. Renal Association Clinical Practice Guideline on haemodialysis. BMC Nephrol. 2019;20(1):379.
   doi pubmed
2. Yamamoto M, Matsumoto T, Ohmori H, Takemoto M, Ikeda M, Sumimoto R, Kobayashi T, et al. Effect of increased blood flow rate on renal anemia and hepcidin concentration in hemodialysis patients. BMC Nephrol. 2021;22(1):221.
   doi pubmed
3. Kaysen GA, Dubin JA, Muller HG, Mitch WE, Rosales LM, Levin NW. Relationships among inflammation nutrition and physiologic mechanisms establishing albumin levels in hemodialysis patients. Kidney Int. 2002;61(6):2240-2249.
   doi pubmed
4. Brown-Tortorici AR, Naderi N, Tang Y, Park C, You AS, Norris KC, Obi Y, et al. Serum albumin is incrementally associated with increased mortality across varying levels of kidney function. Nutrition. 2020;79-80:110818.
   doi pubmed
5. Clinical practice guidelines for nutrition in chronic renal failure. K/DOQI, National Kidney Foundation. Am J Kidney Dis. 2000;35(6 Suppl 2):S17-S104.
   doi pubmed
6. US-DOPPS (Dialysis Outcomes and Practice Patterns Study) Practice Monitor. Serum albumin (3 month average), categories; 2020. https://www.dopps.org/DPM/Files/meanalbumingdl_c_overallTAB.htm. Accessed May 25, 2020.
7. Lowrie EG, Lew NL. Death risk in hemodialysis patients: the predictive value of commonly measured variables and an evaluation of death rate differences between facilities. Am J Kidney Dis. 1990;15(5):458-482.
   doi pubmed
8. Eriguchi R, Obi Y, Streja E, Tortorici AR, Rhee CM, Soohoo M, Kim T, et al. Longitudinal associations among renal urea clearance-corrected normalized protein catabolic rate, serum albumin, and mortality in patients on hemodialysis. Clin J Am Soc Nephrol. 2017;12(7):1109-1117.
   doi pubmed
9. Ye X, Dekker MJE, Maddux FW, Kotanko P, Konings C, Raimann JG, van der Sande FM, et al. Dynamics of nutritional competence in the last year before death in a large cohort of US hemodialysis patients. J Ren Nutr. 2017;27(6):412-420.
   doi pubmed
10. Kalantar-Zadeh K, Kilpatrick RD, Kuwae N, McAllister CJ, Alcorn H, Jr., Kopple JD, Greenland S. Revisiting mortality predictability of serum albumin in the dialysis population: time dependency, longitudinal changes and population-attributable fraction. Nephrol Dial Transplant. 2005;20(9):1880-1888.
    doi pubmed
11. Kaysen GA, Dubin JA, Muller HG, Mitch WE, Rosales L, Levin NW, HEMO GROUP. Impact of albumin synthesis rate and the acute phase response in the dual regulation of fibrinogen levels in hemodialysis patients. Kidney Int. 2003;63(1):315-322.
    doi pubmed
12. Giordano M, Feo P, Lucidi P, de PE, Giordano G, Infantone L, Zoccolo AM, et al. Increased albumin and fibrinogen synthesis in hemodialysis patients with normal nutritional status. J Am Soc Nephrol. 2001;12(2):349-354.
    doi pubmed
13. van Gelder MK, Abrahams AC, Joles JA, Kaysen GA, Gerritsen KGF. Albumin handling in different hemodialysis modalities. Nephrol Dial Transplant. 2018;33(6):906-913.
    doi pubmed
14. Yeun JY, Kaysen GA. Factors influencing serum albumin in dialysis patients. Am J Kidney Dis. 1998;32(6 Suppl 4):S118-125.
    doi pubmed
15. Niwa T, Yazawa T, Kodama T, Uehara Y, Maeda K, Yamada K. Efficient removal of albumin-bound furancarboxylic acid, an inhibitor of erythropoiesis, by continuous ambulatory peritoneal dialysis. Nephron. 1990;56(3):241-245.
    doi pubmed
16. Himmelfarb J, McMonagle E. Albumin is the major plasma protein target of oxidant stress in uremia. Kidney Int. 2001;60(1):358-363.
    doi pubmed
17. Krieter DH, Canaud B. High permeability of dialysis membranes: what is the limit of albumin loss? Nephrol Dial Transplant. 2003;18(4):651-654.
    doi pubmed
18. Tsuchida K, Minakuchi J. Albumin loss under the use of the high-performance membrane. Contrib Nephrol. 2011;173:76-83.
    doi pubmed
19. Ward RA, Beck W, Bernardo AA, Alves FC, Stenvinkel P, Lindholm B. Hypoalbuminemia: a price worth paying for improved dialytic removal of middle-molecular-weight uremic toxins? Nephrol Dial Transplant. 2019;34(6):901-907.
    doi pubmed
20. Samtleben W, Dengler C, Reinhardt B, Nothdurft A, Lemke HD. Comparison of the new polyethersulfone high-flux membrane DIAPES HF800 with conventional high-flux membranes during on-line haemodiafiltration. Nephrol Dial Transplant. 2003;18(11):2382-2386.
    doi pubmed
21. Belmouaz M, Bauwens M, Hauet T, Bossard V, Jamet P, Joly F, Chikhi E, et al. Comparison of the removal of uraemic toxins with medium cut-off and high-flux dialysers: a randomized clinical trial. Nephrol Dial Transplant. 2020;35(2):328-335.
    doi pubmed
22. Yeter HH, Korucu B, Akcay OF, Derici K, Derici U, Arinsoy T. Effects of medium cut-off dialysis membranes on inflammation and oxidative stress in patients on maintenance hemodialysis. Int Urol Nephrol. 2020;52(9):1779-1789.
    doi pubmed
23. Fournier A, Birmele B, Francois M, Prat L, Halimi JM. Factors associated with albumin loss in post-dilution hemodiafiltration and nutritional consequences. Int J Artif Organs. 2015;38(2):76-82.
    doi pubmed
24. Kawanishi H, Mineshima M, Takezawa S, Masakane I, Minakuchi J, Akizawa T, et al. New quality standard for dialysis fluid and the functional classification of dialyzer. J Jpn Soc Dial Ther. 2005;38:149-154. (in Japanese).
25. Wizemann V, Lotz C, Techert F, Uthoff S. On-line haemodiafiltration versus low-flux haemodialysis. A prospective randomized study. Nephrol Dial Transplant. 2000;15(Suppl 1):43-48.
    doi pubmed
26. Meyer JM, Steer D, Weber LA, Zeitone A, Thakuria M, Ho HH, et al. Clinical performance of the Optiflux® F160NR dialyzer. National Kidney Foundation 2020 Spring Clinical Meetings. Available from: https://symposium1.blob.core.windows.net/nkf2020scm/submissions/00001065/poster/ePoster-92ab1a36-229a-2946-472c-09e2f514bf75.pdf.
27. Zhou M, Ficociello LH, Costanzo M, Costanzo M, Mullon C, Kossmann RJ. Evaluation of biomarkers in chronic hemodialysis (HD) patients dialyzed with Optiflux high-flux dialyzers. National Kidney Foundation 2020 Spring Clinical Meetings. Available from: https://symposium1.blob.core.windows.net/nkf2020scm/submissions/00001447/poster/ePoster-102a8107-81d4-5cc4-9da5-5da4a3417611.pdf.
28. Ahrenholz PG, Winkler RE, Michelsen A, Lang DA, Bowry SK. Dialysis membrane-dependent removal of middle molecules during hemodiafiltration: the beta2-microglobulin/albumin relationship. Clin Nephrol. 2004;62(1):21-28.
    doi pubmed
29. Santoro A, Canova C, Mancini E, Deppisch R, Beck W. Protein loss in on-line hemofiltration. Blood Purif. 2004;22(3):261-268.
    doi pubmed
30. Krieter DH, Hackl A, Rodriguez A, Chenine L, Moragues HL, Lemke HD, Wanner C, et al. Protein-bound uraemic toxin removal in haemodialysis and post-dilution haemodiafiltration. Nephrol Dial Transplant. 2010;25(1):212-218.
    doi pubmed
31. Melo NC, Moyses RM, Elias RM, Castro MC. Reprocessing high-flux polysulfone dialyzers does not negatively impact solute removal in short-daily online hemodiafiltration. Hemodial Int. 2014;18(2):473-480.
    doi pubmed
32. Combarnous F, Tetta C, Cellier CC, Wratten ML, Custaud, De Catheu T, Fouque D, et al. Albumin loss in on-line hemodiafiltration. Int J Artif Organs. 2002;25(3):203-209.
    doi pubmed
33. Meert N, Eloot S, Schepers E, Lemke HD, Dhondt A, Glorieux G, Van Landschoot M, et al. Comparison of removal capacity of two consecutive generations of high-flux dialysers during different treatment modalities. Nephrol Dial Transplant. 2011;26(8):2624-2630.
    doi pubmed
34. Yamashita AC, Sakurai K. Clinical effect of pre-dilution hemodiafiltration based on the permeation of the hemodiafilter. Contrib Nephrol. 2015;185:1-7.
    doi pubmed
35. Vanholder R, De Smet R, Lameire N. Protein-bound uremic solutes: the forgotten toxins. Kidney Int Suppl. 2001;78:S266-270.
    doi
36. Vega A, Quiroga B, Abad S, Aragoncillo I, Arroyo D, Panizo N, Lopez-Gomez JM. Albumin leakage in online hemodiafiltration, more convective transport, more losses? Ther Apher Dial. 2015;19(3):267-271.
    doi pubmed
37. Kim ST, Yamamoto C, Taoka M, Takasugi M. Programmed filtration, a new method for removing large molecules and regulating albumin leakage during hemodiafiltration treatment. Am J Kidney Dis. 2001;38(4 Suppl 1):S220-223.
    doi pubmed
38. Hutchison CA, Harding S, Mead G, Goehl H, Storr M, Bradwell A, Cockwell P. Serum free-light chain removal by high cutoff hemodialysis: optimizing removal and supportive care. Artif Organs. 2008;32(12):910-917.
    doi pubmed
39. Ikizler TA, Flakoll PJ, Parker RA, Hakim RM. Amino acid and albumin losses during hemodialysis. Kidney Int. 1994;46(3):830-837.
    doi pubmed
40. Gil HW, Yang JO, Lee EY, Lee EM, Choi JS, Hong SY. The effect of dialysis membrane flux on amino acid loss in hemodialysis patients. J Korean Med Sci. 2007;22(4):598-603.
    doi pubmed
41. Yang CS, Chen SW, Chiang CH, Wang M, Peng SJ, Kan YT. Effects of increasing dialysis dose on serum albumin and mortality in hemodialysis patients. Am J Kidney Dis. 1996;27(3):380-386.
    doi pubmed
42. Kaysen GA, Rathore V, Shearer GC, Depner TA. Mechanisms of hypoalbuminemia in hemodialysis patients. Kidney Int. 1995;48(2):510-516.
    doi pubmed
43. Sombolos K, Tsitamidou Z, Kyriazis G, Karagianni A, Kantaropoulou M, Progia E. Clinical evaluation of four different high-flux hemodialyzers under conventional conditions in vivo. Am J Nephrol. 1997;17(5):406-412.
    doi pubmed
44. Klingel R, Ahrenholz P, Schwarting A, Rockel A. Enhanced functional performance characteristics of a new polysulfone membrane for high-flux hemodialysis. Blood Purif. 2002;20(4):325-333.
    doi pubmed
45. Schmidt JJ, Hafer C, Clajus C, Hadem J, Beutel G, Schmidt BM, Kielstein JT. New high-cutoff dialyzer allows improved middle molecule clearance without an increase in albumin loss: a clinical crossover comparison in extended dialysis. Blood Purif. 2012;34(3-4):246-252.
    doi pubmed
46. Tomo T, Matsuyama M, Nakata T, Kadota J, Toma S, Koga N, Fukui H, et al. Effect of high fiber density ratio polysulfone dialyzer on protein removal. Blood Purif. 2008;26(4):347-353.
    doi pubmed
47. Munoz R, Gallardo I, Valladares E, Saracho R, Martinez I, Ocharan J, Montenegro J. Online hemodiafiltration: 4 years of clinical experience. Hemodial Int. 2006;10(Suppl 1):S28-32.
    doi pubmed
48. Orasan RA, Patiu IM, Anghel D, Bejan C, Iosub L, Totolici C, Pop M, et al. Variation of clinical and laboratory features in chronic dialysis patients treated with high-flux hemodialysis after switching to online hemodiafiltration. Int Urol Nephrol. 2013;45(5):1415-1422.
    doi pubmed
49. den Hoedt CH, Bots ML, Grooteman MP, van der Weerd NC, Mazairac AH, Penne EL, Levesque R, et al. Online hemodiafiltration reduces systemic inflammation compared to low-flux hemodialysis. Kidney Int. 2014;86(2):423-432.
    doi pubmed
50. Potier J, Queffeulou G, Bouet J. Are all dialyzers compatible with the convective volumes suggested for postdilution online hemodiafiltration? Int J Artif Organs. 2016;39(9):460-470.
    doi pubmed
51. Ouseph R, Hutchison CA, Ward RA. Differences in solute removal by two high-flux membranes of nominally similar synthetic polymers. Nephrol Dial Transplant. 2008;23(5):1704-1712.
    doi pubmed
52. Vanholder R, Pedrini LA. All high-flux membranes are equal but some high-flux membranes are less equal than others. Nephrol Dial Transplant. 2008;23(5):1481-1483.
    doi pubmed
53. Duranti D, Ralli C, Imperiali P, Bagnati M. Purifying capacity of polynephron a new membrane evolution of standard polyetheresulphone. ARC J Nephrol. 2017;2(2):4-7.

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