Different elimination patterns of β‐trace protein, β₂‐microglobulin and cystatin C in haemodialysis, haemodiafiltration and haemofiltration

Abstract

Objective. Low molecular mass proteins (LMMP) are putative uraemic toxins, but their elimination is negligible in standard haemodialysis (HD). In this study, we used β₂‐microglobulin, cystatin C and β‐trace protein, which differ in molecular mass and charge, to characterize the elimination patterns of three different dialysis modalities. Material and methods. Plasma samples were obtained at the start, 30 min after the start, at the end of the dialysis treatment and 30 min after termination of the dialysis session. Seventeen patients were treated with low‐flux HD, 13 with post‐dilution haemodiafiltration (HDF) and 8 with pre‐dilution haemofiltration (HF). The changes in concentrations of the three LMMPs were monitored and expressed as percentages of the concentrations at the start of treatments. Results. Conventional HD with low‐flux membranes showed a high elimination of small molecules (urea and creatinine), but did not reduce the levels of the three LMMPs studied. During HDF and HF, there was a significant decrease in the plasma levels of cystatin C (to 28 % and 44 %, respectively) (p<0.001) and of β₂‐microglobulin (to 23 % and 33 %, respectively) (p<0.001). However, the level of β‐trace protein was significantly reduced (to 65 %) only after HDF. Conclusions. The three dialysis modalities showed significantly different elimination patterns for the LMMPs studied. Elimination of β‐trace protein was lower than those of cystatin C and β₂‐microglobulin both in HDF and HF. β‐trace protein was only moderately eliminated by HDF and not at all by HF, and may be a useful marker in the evaluation of different convective therapies.

• Beta 2‐microglobulin
• cystatins
• dialysis
• haemofiltration
• kidney artificial

Acknowledgements

We thank Kerstin Wingren, Karin Nordwall and Bodil Jönsson for their generous support and excellent patient management during the present study. The investigation was supported by grants from the Swedish Science Research Council (Project No. 5196), from the A. Österlund and G. and J. Kock Foundations, from the Medical Faculty of the University of Lund and from Region Skåne.