Objective: Ascorbic acid is endogenously converted to oxalate and appears to increase the absorption of dietary oxalate, supplementation may increase the risk of kidney stones. In this study is aimed to investigate the relation between the calcium oxalate crystals and urinary ascorbic acid in the subjects diagnosed to have calcium oxalate crystals by routine urinary analysis in this study.

Materials and Methods: Forty subjects with calcium oxalate crystals were enrolled as calcium oxalate group and a 40 subjects with no urinary calcium oxalate crystals were enrolled as control group. Serum and urinary ascorbic acid were measured by a colorimetric method.

Results: The urinary ascorbic acid, protein, pH, density levels were increased significantly in the calcium oxalate group as compared to controls (p<0.05). In the calcium oxalate group, positive correlations were found between the ascorbic acid and calcium oxalate crystals (p<0.05; r= 0.370) and protein (p<0.05; r= 0.384), calcium oxalate and density, (p<0.05; r= 0.376). Also in the same group, there were positive correlations between proteinuria and density (p<0.01; r= 0.602) and erythrocyte (p<0.05; r= 0.372).

Conclusion: As a result, in the patients determined to have calcium oxalate crystals both ascorbic acid and protein levels were increased. In addition, there was a positive correlation between urinary calcium oxalate and ascorbic acid levels. We think that increased urinary calcium oxalate levels might be explained by conversion of ascorbic acid to oxalate via some mechanisms.