In this study, simultaneous removal assessment of marker molecules from three uremic toxin groups was performed during different hemodialysis treatment modalities using optical characteristics of spent dialysate. Results from optical measurements were compared with the results from chemical laboratory. Ten chronic dialysis patients, mean age 59 ± 15 years, were included in the study during 40 hemodialysis sessions. Low-flux hemodialysis (HD), high-flux hemodialysis (HF), and postdilutional online hemodiafiltration (HDF) with different settings were used. The reduction ratio (RR) and total removed solute (TRS) of three uremic solutes were determined: small molecular weight urea, middle molecular β2-microglobulin (B2M), and protein-bound indoxyl sulfate (IS). Concentrations of these solutes in the spent dialysate were measured by laboratory (lab) and optical (opt) methods, in the serum by laboratory methods, and calculated RR values in percentage were compared accordingly. Total removed solute was obtained from the total dialysate collection (TDC) using lab and opt methods. The highest RR values were found for urea and B2M, and the lowest for IS. The difference between RR of lab and opt results estimated as mean accuracy (BIAS) was ≤8.1% for all three solutes. Good correspondence between TRS lab vs. opt was achieved, resulting in strong linear correlation values R from 0.727 for urea to 0.971 for IS. Accuracy for TRS values as BIAS ± standard error (SE), comparing lab vs. opt, showed no statistical difference for any of the observed uremic solutes (P > 0.05). The accuracy of the optical method was not influenced by the dialysis modality (HD, HF, and HDF).

No abstract

No abstract

AimIn this work we estimated the contribution of the fluorescence of 4-pyridoxic acid (4-PA) to the total fluorescence of spent dialysate with the aim of evaluating the on-line monitoring of removal of this vitamin B-6 metabolite from the blood of patients with end-stage renal disease (ESRD).MethodsSpectrofluorometric analysis of spent dialysate, collected from hemodialysis and hemodiafiltration sessions of 10 patients receiving regularly pyridoxine injections after dialysis treatment, was performed in the range of Ex/Em 220–500 nm. 4-PA in dialysate samples was identified and quantified using HPLC with fluorescent and MS/MS detection.ResultsAveraged HPLC chromatogram of spent dialysate had many peaks in the wavelength region of Ex320/Em430 nm where 4-PA was the highest peak with contribution of 42.2±17.0% at the beginning and 47.7±18.0% in the end of the dialysis. High correlation (R = 0.88–0.95) between 4-PA concentration and fluorescence intensity of spent dialysate was found in the region of Ex310-330/Em415-500 nm, respectively.Conclusion4-PA elimination from the blood of ESRD patients can be potentially followed using monitoring of the fluorescence of the spent dialysate during dialysis treatments.

No abstract