Dialysis water treated by reverse osmosis decreases the levels of C-reactive protein in uremic patients

Abstract

Atherosclerosis is a major complication of chronic renal failure. Microinflammation is involved in atherogenesis and is associated with uremia and dialysis. The role of dialysate water contamination in inducing inflammation has been debated. Our aim was to study inflammatory markers in patients on chronic dialysis, before and 3 to 6 months after switching the water purification system from deionization to reverse osmosis. Patients had demographic, clinical and nutritional information collected and blood drawn for determination of albumin, ferritin, C-reactive protein (CRP), interleukin-6, and tumor necrosis factor-α in both situations. Acceptable levels of water purity were less than 200 colony-forming units of bacteria and less than 1 ng/ml of endotoxin. Sixteen patients died. They had higher median CRP (26.6 vs 11.2 mg/dl, P = 0.007) and lower median albumin levels (3.1 vs 3.9 g/l, P < 0.05) compared to the 31 survivors. Eight patients were excluded because of obvious inflammatory conditions. From the 23 remaining patients (mean age ± SD: 51.3 ± 13.9 years), 18 had a decrease in CRP after the water treatment system was changed. Overall, median CRP was lower with reverse osmosis than with deionization (13.2 vs 4.5 mg/l, P = 0.022, N = 23). There was no difference in albumin, cytokines, subjective global evaluation, or clinical and biochemical parameters. In conclusion, uremic patients presented a clinically significant reduction in CRP levels when dialysate water purification system switched from deionization to reverse osmosis. It is possible that better water treatments induce less inflammation and eventually less atherosclerosis in hemodialysis patients.

Dialysis Water Treatment Systems: From past to Present

“…Nello studio di Laurence (12) viene presa in considerazione l'efficacia di diversi tipi di trattamento dell'acqua partendo da quella di rete; i risultati dello studio evidenziano che il tipo di trattamento che riscuote maggior successo in termini di efficacia è l'osmosi inversa; tale trattamento è utilizzato nel 61% dei Centri per produrre una qualità di acqua la cui purezza rispondesse alle caratteristiche proposte dal CDC. Lo studio di Vorbeck-Meister (13) evidenzia che l'osmosi inversa, rispetto alla deionizzazione, è in grado di abbattere in maniera significativa le endotossine nel liquido di dialisi, mentre Thomè (14) dimostra che nei pazienti uremici i valori di proteina C reattiva diminuiscono quando si passa dalla deionizzazione all'osmosi inversa. Per tali ragioni, l'osmosi inversa è il processo di trattamento dell'acqua attualmente più utilizzato.…”

Endotoxins and inflammation in hemodialysis patients

“…To explain a persistent micro‐inflammatory state in uremic patients, several factors should be considered, including: the extracorporeal circulation using bioincompatible foreign materials, contact of blood with endotoxins from the dialysate water, frequent infections, and probably the uremic state itself. This status may be recognized by induction of cytokines such as interleukin (IL)‐1β, IL‐6, and tumor necrosis factor‐α and elevation of acute‐phase reaction proteins like C‐reactive protein (CRP) which may be considered as one of the best markers of inflammation in uremic patients …”

“…The role of dialysate water contamination in inducing inflammation has been debated. Thomé et al . reported that uremic patients presented a clinically significant reduction in CRP levels when dialysate water purification system was switched from deionization to reverse osmosis.…”

“…This status may be recognized by induction of cytokines such as interleukin (IL)-1b, IL-6, and tumor necrosis factor-a and elevation of acute-phase reaction proteins like C-reactive protein (CRP) which may be considered as one of the best markers of inflammation in uremic patients. 4 Endothelial dysfunction represents a key early step in the development of atherosclerosis and is also involved in plaque progression and the occurrence of atherosclerotic complications. 5 Intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) are two members of the immunoglobulin-like supergene family that are synthesized by endothelial cells.…”

Bacterial DNA in Water and Dialysate: Detection and Significance for Patient Outcomes

“…A Diasafe filter can be used to remove highmolecular-weight endotoxin components [11,12] . For example, switching from a deionizer to a reverse osmosis system led to decreased patient C-reactive protein levels [13] . Systems are periodically disinfected and flushed with chemicals in an effort to remove biofilm [14,15] .…”