A Multicenter Study of Removed Uric Acid Estimated by Ultra Violet Absorbance in the Spent Dialysate

The aim of this study was to investigate the relation between removed uric acid (UA) and measured ultra violet (UV) absorbance of the spent dialysate during dialysis. Ten uremic patients from Tallinn and ten from Linköping, during 30+40 haemodialysis treatments, were followed at the Departments of Dialysis and Nephrology at North-Estonian Medical Centre and at Linköping University Hospital. The dialysate samples were taken and analyzed by means of UA concentration at the chemical laboratory and with a doublebeam spectrophotometer. UV absorbance at the wavelength of 297 nm was transformed into UA concentration in the spent dialysate using the regression model from the total material, noted as general model. Mean concentration of UA was 53,4 ± 22,7 micromol/l measured at the chemical laboratory, and 53,4 ± 21,4 micromol/l determined by UV-absorbance. The results were not significantly different (p < 0.05). The concentrations found did differ less than 10%. Our study indicates that the removed UA can be reliably estimated in different dialysis centres by the UV technique.