Urinary Oxalate Excretion in Patients with Urolithiasis

Urinary oxalic acid excretion was determined in 21 healthy people and 70 patients with renal stones. In the group of 31 patients with calcium oxalate-containing renal stones the mean value of urinary oxalate exretion was significantly higher than both in the normals and the patients with non-oxalate renal stones. Urinary oxalate excretion above the upper limit was found in 12 patients with calcium oxalate-containing renal stones (38.7%) and in one patient with radio-paque renal stones and nephrocalcinosis. In the patients with hyperoxaluria great variability in oxalate excretion was found. There was no relationship between urinary oxalate and calcium excretion and between urinary oxalate excretion and 24-hour volume of urine. It is suggested that there is relationship between the increased urinary oxalate excretion and recurrent calcium oxalate-containing renal stones formation in the investigated group of patients.