Optical measurement of creatinine in spent dialysate.

Ruth Tomson, Ivo Fridolin, Fredrik Uhlin, Jana Holmar, Kai Lauri, Merike Luman

Department of Biomedical Engineering, Technomedicum, Tallinn University of Technology, Tallinn, Estonia. ruth@cb.ttu.ee

Clinical nephrology 2013 Feb

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The aim of the study was to develop an optical method for the estimation of creatinine (Cr) removal during dialysis using UV-absorbance. 29 hemodialysis patients on chronic 3-times-a-week hemodialysis were studied in 6 separate studies. Double-beam pectrophotometer was used for the determination of UV-absorbance in the collected spent dialysate samples. A single wavelength (SW) and a multi-wavelength (MW) model were developed using stepwise regression utilizing Cr values from the laboratory as the dependent parameter. The reduction ratio (RR) and total removed Cr (TRCr) were estimated. For blood-Cr RRb (mean ± SD) was 60.9 ± 5.0% (calibration set) and 58.1 ± 6.0% (validation set), for SW UVabsorbance RR_SW was 61.5 ± 5.9% and 57.3 ± 6.0%, and for MW UV-absorbance RR_MW was 65.8 ± 5.8% and 61.7 ± 6.4% respectively. RR_SW and RRb were not statistically different. RR_MW was higher compared to RRb (p < 0.05). TRCr_lab was 13.8 ± 3.8 mmol, TRCr_SW 14.5 ± 2.5 mmol and TRCr_MW 13.8 ± 2.6 mmol, being not statistically different. In summary, creatinine removal during dialysis can be estimated as reduction ratio and total removed creatinine with the UV-absorbance technique.

Citation

Ruth Tomson, Ivo Fridolin, Fredrik Uhlin, Jana Holmar, Kai Lauri, Merike Luman. Optical measurement of creatinine in spent dialysate. Clinical nephrology. 2013 Feb;79(2):107-17