Estimation of removed uremic toxin indoxyl sulphate during hemodialysis by using optical data of the spent dialysate

Abstract

The aim of this study was to explore the possibility to determine the amount of total removed Indoxyl Sulphate (TR_IS) during dialysis session, an optical method utilizing absorbance and fluorescence spectral data of the spent dialysate was used. Eight uremic patients from Linköping, Sweden and 10 from Tallinn, Estonia, were studied during dialysis treatments. Dialysate samples were taken during each treatment and analyzed at a laboratory. Fluorescence and absorbance spectra of the spent dialysate were measured with spectrofluorophotometer and spectrophotometer. The spectral values were transformed into IS concentration using multiple linear regression model from the total material noted as optical method (Opt). IS concentration was estimated using high-performance liquid chromatography (HPLC) method as a reference. TR_IS values were calculated. Achieved results were compared regarding mean values and SD and collated with the amount of total removed urea value (TR_Urea) for the same dialysis procedures. Mean TR value ± SD (mg) for urea was 28 947 ± 9 241; TR for IS was 151.4 ± 87.3 estimated by HPLC and 149.4 ± 84.9 estimated by Opt. The TR_IS values were not significantly different (p ≤ 0.05). This study indicates, that it is possible to estimate TR_IS using only spectral values of the spent dialysate and the parameter can be used for quantifying the elimination of protein bound uremic toxins during the dialysis procedure.

Identification and characterisation of fluorescent substances in spent dialysis fluid

“…As one example, the presence of proteins and their binding affinity towards those toxins influences the removal of protein-bound uraemic toxins during dialysis. Although there are several attempts done to correlate the fluorescence of spent dialysis fluid with the removal of protein-bound uraemic toxins from blood serum, 13 it could be pointed out in this work that there are more culprits causing fluorescence in spent dialysis fluid, among them amino acids like Y or W. Therefore, more advanced techniques shall be developed in order to derive an online method with which fluorescence of spent dialysate fluid can be linked to the removal uraemic toxins like IS. Composing of single fluorescence spectra in order to reconstruct the overall fluorescence spectrum as performed in this work might be one potential technique.…”

“…The fluorescence properties of spent dialysis fluid have not drawn similar scientific attention, even if haemodialysis is the most common replacement therapy for end-stage renal disease, and knowledge about removed toxins may help to optimise the extracorporeal blood treatment. One of the few investigations of spent dialysis fluid was performed by Holmar et al, 13 who correlated the fluorescence of spent dialysis fluid with the concentration of indoxyl sulphate. However, other substances contributing to or diminishing the fluorescence in spent dialysis fluid were not taken into account.…”

Continuing education: online monitoring of haemodialysis dose

“…The values differ at most by about 20% to both directions. In addition to UV light absorption, also fluorescence has been used for quantitation of removal of uraemic toxins by dialysis (Holmar et al 2011;Holmar et al 2013;Arund et al 2016).…”

Optical Method and Biochemical Source for the Assessment of the Middle-Molecule Uremic Toxin β2-Microglobulin in Spent Dialysate

“…As a result, the UV monitoring of the removal of low molecule weight uremic solutes by HD treatment has become commonly applied in the treatment practice worldwide [ 18 , 19 , 20 ]. Furthermore, fluorescence of spent dialysate has proved to be well applicable for on-line removal monitoring of protein-bound uremic toxins [ 21 , 22 , 23 ]. However, many recent publications have confirmed the essential role of middle molecule (MM) group of uremic toxins in pathology and mortality of ESKD patients [ 24 , 25 , 26 , 27 , 28 ].…”