Dietary salt, urinary calcium, and kidney stone risk.

Both salt-loading studies and reports of free-living populations find that urinary calcium excretion increases approximately 1 mmol (40 mg) for each 100 mmol (2300 mg) increase in dietary sodium in normal adults. Renal calcium stone-formers with hypercalciuria appear to have greater proportional increases in urinary calcium (approximately 2 mmol) per 100 mmol increase in salt intake. Thus, reduction of dietary NaCl may be a useful strategy to decrease the risk of forming calcium-containing kidney stones.