Optical online monitoring of uric acid removal during dialysis.

This study estimates the total removal of uric acid (TR(UA)) by online UV absorbance measurements in the spent dialysate in two different dialysis centers in Estonia and Sweden. Sixteen dialysis patients were included. All dialysate was collected that gave the reference for TR(UA). Two regression models were investigated: one for each patient (UV1) and one for the entire material (UV2). TR(UA) from the three methods was in the same order but showed a statistically significant difference when the UV2 model was built on data from both centers together. TR(UA), (n = 56) was (mean +/- SD, micromol): 5,854 +/- 1,377 for reference, 6,117 +/- 1,795 for UV1 and 5,762 +/- 1,591 for UV2. Six patients were monitored 1 year after the first study session, using the same models as the previous year, still having a nonsignificant difference. The results show the possibility of estimating TR(UA) by using UV absorbance. The method appeared to be reliable also in long-term patient monitoring.