Utilization of UV absorbance for estimation of phosphate elimination during hemodiafiltration.
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).


CONCLUSIONS
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.
Department of Nephrology UHL, County Council of Östergötland, Linköping, Sweden. peren335@student.liu.se
Per
P
Enberg
Ivo
I
Fridolin
Jana
J
Holmar
Anders
A
Fernström
Fredrik
F
Uhlin
D000368:Aged; D000369:Aged, 80 and over; D015314:Dialysis Solutions / Q000737:chemistry*; D005260:Female; D017583:Hemodiafiltration; D006801:Humans; D007676:Kidney Failure, Chronic / Q000628:therapy; D008297:Male; D055641:Mathematical Concepts; D008875:Middle Aged; D008962:Models, Theoretical; D009862:Online Systems; D010710:Phosphates / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet
D015314:Dialysis Solutions; D010710:Phosphates