A randomized cross-over trial of pre-and post-filter hemodiafiltration modalities in children on maintenance dialysis -- effects on solute removal and blood pressure
In brief
Pre-filter HDF cuts middle-molecule toxin levels by 17 ng/ml versus post-filter
In a crossover trial of 21 children on dialysis, pre-filter hemodiafiltration removed significantly more α1-microglobulin, β2-microglobulin and myoglobin than post-filter HDF, while small-molecule clearance and albumin remained unchanged. It also lowered inflammatory markers but was linked to higher diastolic blood pressure, likely from greater sodium load. Further work is needed to balance toxin removal with blood pressure effects.
- Journal
- Kidney international (Q1)
- Published
- 16 September 2026
- Study design
- Randomized controlled trial
- Evidence level
- Level 1, High (CEBM 1b)
- Authors
- Ayse Agbas, Nur Canpolat, Bruno Ranchin, Claus Peter Schmitt, Sacha Flammier, Miriam Scwetlick, et al.
- PMID
- 42749052
- DOI
- 10.1016/j.kint.2026.07.032
Why clinicians should know about it
- Picked for Nephrology (top studies of the week, 20 September 2026): Randomized cross‑over trial of pre‑ vs post‑filter HDF in children
Abstract
INTRODUCTION: Children on post-filter hemodiafiltration (post-HDF) have reduced cardiovascular damage and improved growth compared to conventional hemodialysis. High convection volumes in post-HDF are associated with improved outcomes. Even higher convection volumes can be reached with pre-filter HDF (pre-HDF). However, data is limited. Here, we compare the effect of pre- vs post-HDF on solute removal, inflammation, nutrition markers and blood pressure in a randomized, multicenter cross-over trial. METHODS: After a four-week wash-out period in post-HDF, 24 children on maintenance dialysis were randomized either to four-weeks pre- then four-weeks post-HDF, or vice-versa, keeping all other dialysis related parameters constant. The primary outcome measure was reduction in α1-microglobulin, a large-middle molecular weight (MW) uremic retention solute. RESULTS: Twenty-one patients completed the study. The median age was 15.1 years, with 15(71%) girls. Median convection volumes were 36.2 (inter quartile range 32;40) vs 14.3 (12.9;15.8) l/m2 body surface area per session in pre-HDF and post-HDF respectively. Pre-dialysis α1- microglobulin [median difference -17.0 ng/ml (95% confidence interval (CI) -27.0;-3.5)], ß2-microglobulin [-5.19 mg/l (95%CI -9.34;-1.76)] and myoglobin [-76.0 ng/ml (95%CI-100;-44.5)] concentrations were significantly lower, and reduction ratios (RR) were significantly higher in pre-HDF compared with post-HDF. Interleukin-10, tumor necrosis factor-α and high sensitivity C-reactive protein were significantly lower in pre-HDF. Pre-HDF achieved significantly higher RRs of total indoxyl sulfate and p-cresyl sulfate. The RR for small MW solutes, Kt/V and serum albumin did not differ meaningfully between modalities. Diastolic blood pressure was significantly higher in pre-HDF, correlating with higher replacement volume and higher post-dialysis serum sodium concentration. CONCLUSIONS: Pre-HDF achieves superior removal of middle and larger-middle MW uraemic retention solutes and was associated with a more favorable inflammatory profile, without compromising small MW retention solute removal or albumin levels, compared to post-HDF. Pre-HDF may be associated with higher blood pressure in a sub-set of patients, potentially due to greater sodium load from higher replacement volumes.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.