Effects of sodium citrate, potassium citrate, and citric acid in preventing experimental calcium oxalate urolithiasis in rats

Male Wistar-strain rats which had been fed a glycolic-acid diet developed severe nephrocalcinosis with urinary calculi within 4 weeks. Rats fed the same diet with citrate salts added had, however, either slight or no nephrocalcinosis without any stones in the urinary system. Nephrocalcinosis intermediate between those in the citrate groups and the glycolic-acid group, with some urinary calculi, was observed in the citric-acid group. During the experiment, the urinary oxalate concentration increased markedly and was higher in the citrate and citric-acid than in the glycolic-acid group. The urinary citrate concentration was significantly higher in the citrate groups and lower in the citric acid and glycolic-acid groups. Therefore, citrate salts can be concluded to inhibit nephrocalcinosis and calculi formation as a result of decreased urinary saturation by means of increase in urinary citrate, in spite of a slight increase in the urinary oxalate.