4-Pyridoxic Acid in the Spent Dialysate: Contribution to Fluorescence and Optical Monitoring.
OBJECTIVE
In 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).


METHODS
Spectrofluorometric 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.


RESULTS
Averaged 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.


CONCLUSIONS
4-PA elimination from the blood of ESRD patients can be potentially followed using monitoring of the fluorescence of the spent dialysate during dialysis treatments.
Department of Biomedical Engineering, Technomedicum, Tallinn University of Technology, Tallinn, Estonia.
Sigrid
S
Kalle
Department of Biomedical Engineering, Technomedicum, Tallinn University of Technology, Tallinn, Estonia.
Risto
R
Tanner
Department of Biomedical Engineering, Technomedicum, Tallinn University of Technology, Tallinn, Estonia.
Jürgen
J
Arund
Department of Biomedical Engineering, Technomedicum, Tallinn University of Technology, Tallinn, Estonia.
Ruth
R
Tomson
Department of Biomedical Engineering, Technomedicum, Tallinn University of Technology, Tallinn, Estonia.|Centre of Nephrology, North Estonian Medical Centre, Tallinn, Estonia.
Merike
M
Luman
Department of Biomedical Engineering, Technomedicum, Tallinn University of Technology, Tallinn, Estonia.
Ivo
I
Fridolin
D000368:Aged; D001711:Biotransformation; D002851:Chromatography, High Pressure Liquid; D015314:Dialysis Solutions; D005260:Female; D005453:Fluorescence; D017583:Hemodiafiltration; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000150:complications / Q000175:diagnosis / Q000628:therapy; D008297:Male; D008875:Middle Aged; D011735:Pyridoxic Acid / Q000097:blood*; D013050:Spectrometry, Fluorescence; D025101:Vitamin B 6 / Q000008:administration & dosage / Q000097:blood* / Q000493:pharmacokinetics; D026681:Vitamin B 6 Deficiency / Q000097:blood* / Q000150:complications / Q000175:diagnosis / Q000628:therapy
D015314:Dialysis Solutions; D011735:Pyridoxic Acid; D025101:Vitamin B 6