[The effect of oral calcium loading on the serum magnesium concentration and its urinary excretion in patients with recurrent calcium nephrolithiasis and hypercalciuria--differential diagnostic potentials].

The study deals with 13 healthy controls with normal basic indices for calcium-phosphorus metabolism and 25 patients with recurrent calcium nephrolithiasis and hypercalciuria, 13 of them with renal hypercalciuria and 12 patients with absorptive hypercalciuria. The oral calcium-tolerance test was carried out in all persons. The changes in the serum and urine calcium and magnesium concentrations following the calcium loading are recorder. A statistically significant increase of magnesium urine excretion was found in all persons examined, the highest being in the patients with renal hypercalciuria, considerably higher than in the healthy controls. The conclusion is reached that the magnesium urine excretion gives valuable information for the diagnosis of patients with renal hypercalciuria.