STUDIES OF OXALATE METABOLISM IN UROLITHIASIS
2. Excretion of Urinary Oxalate in Stone formers and Healthy Controls
1984 Volume 75 Issue 3 Pages 467-475
Details
1984 Volume 75 Issue 3 Pages 467-475
Urinary oxalate excretion of 160 stone formers (male; 118, female; 42) and 257 healthy controls (male; 207, female; 50) was determined using a high performance liquid chromatographic method.
The following results were obtained:
1) The mean value of urinary oxalate excretion in 207 healthy control men was 31.9±10.6mg/day, and in 50 women it was 26.7±10.3mg/day. In healthy controls, the excretion in men was higher than in women significantly (p<0.01).
The effect of age on urinary oxalate excretion was not demonstrated in adults.
There was no correlation between the urinary volume in 24 hours and the amount of urinary oxalate excretion.
2) Calcium stone formers and calcium oxalate stone formers showed significant increases of urinary oxalate compared with each healthy controls in both sexes, but non-calcium stone formers or non-oxalate stone formers did not show significant increases in oxalate in both sexes.
3) There were no differences of urinary oxalate between single stone and recurrent stone among calcium stone formers and calcium oxalate stone formers.
4) We defined “hyperoxaluria” as a state in which the 95% upper confidence limit of urinary oxalate in normal controls were exceeded; the limit was 50mg/day in males and 45mg/day in females.
In our series, both calcium stone formers and calcium oxalate stone formers have an incidence of hyperoxaluria in more than 25%, while the incidence was much lower in non-calcium and non-oxalate stone formers. These results suggest that hyperoxaluria can be considered as the main risk factor in the mechanism of formation of calcium oxalate stone.
5) The diurnal variation in urinary oxalate was measured in 5 non-stone patients. There was an increase of urinary oxalate in the evening, although there was no difference between daytime and night. The day to day variation was measured in three consecutive days in inpatients and in several individual days in outpatients. The variation of the inpatients was smaller than that of the outpatients. It was thought that urinary excretion of oxalate might be influenced by dietary oxalate intake considerably.
