We evaluated the comparability of HPCE methods for measuring urinary oxalate and citrate with photometric and enzymatic ones. HPCE and enzymatic methods for measuring citrate provided well comparable results r = 0.958, mean of differences 7%, range of differences from –33% to +47% for 95% of confidence interval. HPCE and enzymatic method for measuring oxalate showed very poor correlation between results (r = 0.203), mean of differences was 27%, range of differences were from –80% to +134% for the 95% confidence interval. Correlation between results of HPCE and photometric methods was only r = 0.648, mean of differences 4%, its ranges from –70% to +79% for the 95% confidence interval. Lack of selectivity, difficulties of preanalytical conditions, positive and negative interferences of ascorbic acid are the main reasons for this situation. On the other hand high selectivity, no interferences of ascorbic acid and relatively simple preanalytical conditions make the HPCE method a suitable analytical tool for significant improvement of the analytical quality of measuring oxalate in biological materials.

        Key words: urinary oxalate, urinary citrate, linear regression, difference plots, method comparison.