Utilization of UV Absorbance for Estimation of Phosphate Elimination during Hemodiafiltration

Abstract

Background: Phosphate is an important factor in explaining the high progress of vascular calcification among dialysis patients. Today, phosphate concentration is measured in plasma on a regular basis. The aim of this study was to find out if it is possible to estimate total removed phosphate (TRp) in spent dialysate utilizing UV absorbance during hemodiafiltration. Methods: Eleven patients were monitored online with UV absorbance at 297 nm, three times during one week each (n = 33). Dialysate samples were taken at different times during treatment and from a collection tank to chemically determine phosphate concentrations. Two mathematical models (UVIND and UVGROUP) were tested to estimate TRp with supervision by UV absorbance and compared with TRp measured in the tank (reference). Results: High correlation between UV absorbance and phosphate concentration for each single patient and lower for the whole group together was found. TRp was (mean ± SD) 30.7 ± 7.3 mmol for the reference and 30.8 ± 8.2 and 29.1 ± 5.2 mmol for UVIND and UVGROUP, respectively (p > 0.05). Conclusion: This study demonstrates a novel possibility to estimate TRp based on linear relationship between online monitoring of UV absorbance and concentration of phosphate in spent dialysate.

An Optical Method for Serum Calcium and Phosphorus Level Assessment during Hemodialysis

“…Optical monitoring of hemodialysis has been considered as a beneficial and cost-effective alternative to traditional methods to assess the effectiveness of the dialysis procedure without the need of frequent blood sampling [ 20 ]. The optical monitoring possibility of the phosphate removal during dialysis has been suggested by Enberg et al [ 15 ]. This study included 11 patients and 33 dialysis sessions, while absorbance at a single wavelength was used.…”

“…Methods for optical estimation of dialysis quality [ 10 ] and small [ 11 , 12 ], protein bound [ 13 ] and middle [ 14 ] molecular weight uremic retention solutes removal during dialysis has been proposed. Possibility for optical determination of phosphate elimination during dialysis has been also demonstrated [ 15 ].…”

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

“…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.…”

“…Our group has previously shown possibilities to estimate the removal of small water soluble waste solutes during HD, utilizing UV-absorbance within a wavelength range of 280-297 nm [8][9][10] . Since urea certainly is not a representative for all removed solutes, and is known to be rather non-toxic, an optical monitoring technique that is suitable for middle molecule removal could be a valuable complement to urea-based dialysis dose parameters.…”

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

“…While ultraviolet (UV) absorbance monitoring of the spent dialysate [4][5][6] enables determining urea-based dialysis quality parameters [7,8], the potential of optical dialysis monitoring is wider. Earlier Toxins 2021, 13, 255 2 of 15 research has shown the potential of optical monitoring of the spent dialysate to estimate the removal of low molecular weight uremic toxins [9][10][11][12][13][14], elimination of electrolytes, such as phosphate and calcium, [15,16], and possibly for nutrition assessment [17]. 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].…”