Orally or parenterally administered sodium is known to increase urinary calcium in
experimental animals and humans, and there is well-documented correlation between
urinary sodium and calcium in 24-h urine collections from normal subjects and renal stone
formers. The correlation between urinary sodium and calcium is generally sodium driven, ie,
it is the sodium load that influences urinary calcium rather than vice versa, but the converse
may also occur, as after an oral calcium load or in hypercalcemia. When sodium is the …