Effect of dietary intake on urinary oxalate excretion in calcium renal stone formers.

OBJECTIVE

To investigate the influence of dietary intake on urinary oxalate excretion in calcium renal-stone formers.

PATIENTS AND METHODS

Dietary intake was monitored by using the dietary-record method in 60 idiopathic stone formers. The patients collected their urine for 24 h at home and their urinary oxalate excretion rate was determined. The relationship between the daily intake of various nutrients and urinary oxalate excretion was examined by both monovariate and multivariate analyses.

RESULTS

By monovariate analysis, the intake of carbohydrate, total protein and fat were significantly correlated with urinary oxalate excretion, but the intake of calcium and body surface area were not. In addition, the intake of total protein was highly correlated with that of fat. By multivariate analysis, the intake of carbohydrate and fat were significantly related to urinary oxalate excretion, and the intake of calcium was inversely correlated with urinary oxalate excretion, but the intake of total protein showed no significant correlation.

CONCLUSION

The intake of carbohydrate and fat was positively and the intake of calcium was inversely correlated with urinary oxalate excretion in stone formers and, taken together, these findings suggested that fat plays an important role in urinary oxalate excretion and that protein has a minimal effect.