Do Only Small Uremic Toxins, Chromophores, Contribute to the Online Dialysis Dose Monitoring by UV Absorbance?

Abstract

The aim of this work was to evaluate the contributions of the main chromophores to the total UV absorbance of the spent dialysate and to assess removal dynamics of these solutes during optical on-line dialysis dose monitoring. High performance chromatography was used to separate and quantify UV-absorbing solutes in the spent dialysate sampled at the start and at the end of dialysis sessions. Chromatograms were monitored at 210, 254 and 280 nm routinely and full absorption spectra were registered between 200 and 400 nm. Nearly 95% of UV absorbance originates from solutes with high removal ratio, such as uric acid. The contributions of different solute groups vary at different wavelengths and there are dynamical changes in contributions during the single dialysis session. However, large standard deviation of the average contribution values within a series of sessions indicates remarkable differences between individual treatments. A noteworthy contribution of Paracetamol and its metabolites to the total UV absorbance was determined at all three wavelengths. Contribution of slowly dialyzed uremic solutes, such as indoxyl sulfate, was negligible.

Optical Estimation of Beta 2 Microglobulin during Hemodiafiltration - Does It Work?

“…3 ). This has been confirmed also by earlier studies [11,12] . Moreover, HPLC studies have demonstrated that UA is an UV-absorbing solute in the studied wavelength range, and therefore influences the UV-signal substantially [13] .…”

“…For the determination of UV-absorbance (A) in the spent dialysate/ultrafiltrate, described earlier [9][10][11] , a double-beam spectrophotometer (V-570, UV/VIS/NIR spectrophotometer and software version 1.53.01 for Windows, JASCO Corp., Japan) with an accuracy of ±0.3% was used. Scanning at the UV-range 190-400 nm was performed after each session using pure dialysate as reference.…”

Online Kt/V Monitoring in Haemodialysis by UV Absorbance: Variations during Intra-Dialytic Meals

“…Along these lines, several non-uremic solutes, drug metabolites and unidentified molecules that contribute significantly to the UV absorbance signal during dialysis have been found by chromatography in the spent dialysate [11]. One such molecule is uric acid, which has been identified as a major contributor to total dialysate UV absorbance [11]. Interestingly, Kanbay et al [12] found a correlation between dietary fructose intake and elevated uric acid levels.…”

“…However, other rapidly absorbed molecules could account for the changes. Along these lines, several non-uremic solutes, drug metabolites and unidentified molecules that contribute significantly to the UV absorbance signal during dialysis have been found by chromatography in the spent dialysate [11]. One such molecule is uric acid, which has been identified as a major contributor to total dialysate UV absorbance [11].…”

Paracetamol Interference in Uric Acid Levels in Uremic Patients Revealed by Monitoring Spent Dialysate

“…The peak of UA is well separated from peaks of PAR and its metabolites on the chromatograms [12] and any possibility of analytical interference of PAR+ metabolites in HPLC estimation of UA content in spent dialysate seems not to be possible. Consequently, the significant rise of content of UA in spent dialysate after dosage of PAR to ESRD patients in the course of dialysis session seems to really take place at least in some cases of treatments.…”