Behaviour of uremic toxins and UV absorbance in respect to low and high flux dialyzers

Abstract

The aim of this study was to investigate the behaviour of uremic toxins and UV absorbance in respect to low and high flux dialyzers during hemodialysis treatments. Ten uremic patients were investigated using online spectrophotometry, with wavelength of 280 nm, over the course of 30 hemodialysis treatments. The polysulphone dialyzers were used. The taken dialysate and blood samples were analysed using standard biochemical methods and reversed phase HPLC. The chromatographic peaks were detected by a UV detector at wavelengths of 254 and 280 nm. Spiking experiments and UV spectra between 200-400 nm allowed to identify predominant uremic toxins in 5 chromatographic peaks identified as creatinine (CR), uric acid (UA), hypoxanthine (HX), indoxyl sulphate (IS), and hippuric acid (HA). Moreover, two persistent, but non-identified peaks, peak 1 (P1) and peak 2 (P2), were detected. There was no significant difference in the reduction ratio of uremic solutes and the UV absorbance between the low and high flux membranes. The reduction ratios, estimated by the total area of HPLC peaks at 254 nm and 280 nm in the serum and by the online UV absorbance at 280 nm, were closest to the removal of small water-soluble non-protein bound solutes urea, creatinine and uric acid. All studied uremic toxins and UV absorbance showed similar reduction for the low and high flux membranes during hemodialysis.

Development of a method for optical monitoring of creatinine in the spent dialysate

“…This difference could be explained by specific removal characteristics for creatinine compared to the net removal of the UV-absorbing chromophores contributing to the optically measured signal in spent dialysate. Despite that the online UV-absorbance at 280 nm was closest to the removal of small water-soluble non-protein bound solutes like urea, creatinine and uric acid [ 16,17 ], the overall removal pattern is far more complex because each uremic solute has still a distinctive distribution volume in the body and removal rate during dialysis. This is expressed also by independent components in the models, including several wavelengths, proposed in this study.…”

Waves, oscillations and optics in biomedical engineering: research in the Department of Biomedical Engineering 1994–2014

“…The biofluid optics research in the DBME is based on a novel concept of the multicomponent dialysis monitoring, using optical techniques. The multicomponent monitor incorporates online removal estimation of all the three uremic toxins' groups: small molecular weight, middle molecular weight, and protein bound large molecular weight toxins [50][51][52][53][54][55][56][57][58][59][60].…”