Excretion of urinary citric acid in stone patients

Hong, Jong Woo; Choi, Sung Hyup

Abstract

Urinary citric acid reduces urinary saturation of calcium oxalate and phosphate salts by forming complexes with calcium and retards crystallization of stone forming salts. Hypocitraturia, important factor in stone formation, has been 19-63% of stone patients in various reports. We measured the 24 hour excretion of citric acid. calcium and calcium/citric acid ratio in 100 renal stone patients and 30 healthy controls. The results were as follows: 1. The 24-hour urinary excretion of citric acid was lower in stone patients than in controls, but statistically insignificant (P>0.05). 2. The 24-trour urinary excretion of calcium was higher in stone patients significantly than in Controls (P<0.05). 3. In stone patients, hypocitraturia showed in 19 patients (19%), hypercalciuria in 22 patients (22%). 4. The 24-hour urinary excretion of citric acid had positive correlation with 24-hour urinary excretion of calcium in stone patients (P<0.05) 5. Urinary calcium/citric acid ratio was significantly higher in stone patients than in controls (P<0.05). As results, urinary calcium/citric acid ratio was more significant than the amount of citric acid in stone patients, furthermore it seems to be a useful measure for stone formation and recurrence.