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.