The role of oxalate and calcium oxalate activity and formation product ratio in patients with renal stones before and during treatment.

The participation of oxalate in nephrolithiasis was evaluated in 202 stone patients. The activity product and formation product ratios of calcium oxalate were substantially altered in the stone population. Treatment with thiazide derivatives and/or allopurinol was able to decrease urine oxalate and normalize the activity product and formation product ratios. Stone activity decreased in the stone population after treatment. Our data suggest that oxalate may have a critical role in nephrolithiasis activity.