Urine composition in patients with renal stone disease during treatment with allopurinol.

Thirty-four male and seven female patients with urolithiasis were treated with 300 mg allopurinol daily for one year in order to prevent stone recurrences. The mean serum-urate concentration in all patients, and the urine urate excretion in patients with a pre-treatment urate excretion above 250 mmol per mol creatinine were significantly reduced. The mean urinary excretion of calcium, magnesium and oxalate was unaffected by the treatment, although six of eight patients with a pre-treatment oxalate excretion above 25 mmol per mol creatinine demonstrated lower urine oxalate values during the treatment. No significant differences were obtained concerning the calcium/magnesium or calcium x oxalate/magnesium x creatinine quotients, but lower values of the calcium x oxalate x urate/magnesium x creatinine2 quotient were observed during allopurinol administration.