A simple ion--chromatographic method for determination of urinary oxalate

A simple and rapid technique for the determination of oxalate in urine by ion chromatography has been described. Although there is difficulty in separating the oxalate peak from the sulfate peak on the conductivity chromatogram of unprocessed urine, it is possible to eliminate the sulfate peak by the addition of barium chloride to the urine. Using this technique, the author has estimated the urinary oxalate in 33 urolithiasis patients and in 40 non-urolithiasis patients. The means of 50 urinary oxalate determinations in 33 urolithiasis patients and of 42 urinary oxalate determinations in 40 non-urolithiasis patients were 21.5 +/- 11.4 and 19.5 +/- 13.0 mg/gCr, respectively. Of the 33 urolithiasis patients, 17 were calcium stone formers and 6 were non-calcium stone formers whose stones had been analyzed by infrared spectrometry, and the mean urinary oxalate values were 19.4 +/- 6.9 and 21.3 +/- 8.2 mg/gCr, respectively. The urinary oxalate was significantly higher in children under the age of 10 years.