Effect of parathyroidectomy on crystallization of calcium salts in urine of patients with primary hyperparathyroidism.

The effect of parathyroidectomy on the crystallization of calcium salts in urine was examined in seven stone-forming patients with primary hyperparathyroidism. After parathyroidectomy, urinary calcium decreased significantly from 205 +/- 30 to 67 +/- 11 mg per day (P less than 0.01); there were no significant changes in urinary phosphorus, oxalate, magnesium, sodium, potassium, uric acid, pH, or total volume. The urinary activity product ratio (state of saturation) of brushite (CaHPO4.2H2O) and calcium oxalate decreased significantly from 1.34 +/- 0.14 to 0.75 +/- 0.18 and from 3.20 +/- 0.56 to 1.53 +/- 0.21 respectively (P less than 0.05), owing principally to the decline in urinary calcium. Moreover, the urinary formation product ratio of calcium oxalate, which reflects the minimum supersaturation required for spontaneous nucleation, increased significantly after parathyroidectomy, from 7.19 +/- 1.19 to 12.99 +/- 1.69 (P less than 0.001). The results indicate that parathyroidectomy restores the normal urinary environment with respect to saturation and inhibitor and/or promoter activity.