Evidence for Magnesium Depletion in Idiopathic Hypercalciuria

Magnesium accounts for about 20% of the total inhibitory activity of urine with respect to calcium stone formation1. Magnesium depletion has been shown to cause calcification in the proximal tubule cells and in the tubular lumen in rats2 and to be responsible for nephrocalcinosis in children. Based on these data, magnesium deficiency has been suspected as a factor in the pathogenesis of calcium stone formation although it has been observed only rarely3. Moreover, the data on magnesium excretion in stone formers are conflicting, and may even be normal4 or increased5. These discrepancies may be explained by the fact that dietary calcium and calcium excretion were not taken into account, despite the fact that in normal individuals magnesium excretion is directly correlated with calcium excretion6. For these reasons it seemed interesting to us to study magnesium metabolism in various groups of idiopathic calcium stone-formers classified according to calcium excretion during a controlled calcium diet.