Urinary magnesium and oxalic acid excretion in patients with recurrent oxalate urolithiasis.

Of patients with oxalate-containing calculi of the upper urinary tract who were surveyed for stone recurrences after an average of 4 years and 7 months, the relationship between the stone recurrence and the urinary excretion of stone components was studied. Seventy-one cases for urinary calcium and magnesium, 48 cases for phosphorus, 36 cases for oxalic acid, and 29 cases for uric acid were available for estimate. The urinary excretion of calcium, magnesium, phosphorus, and uric acid was the same for noncurrent patients as for recurrent patients. However, the ratio of magnesium to (calcium x oxalic acid) in the urine patients with oxalate stone recurrences was significantly lower than that in the urine of patients without recurrences.