The article by Dickinson and Havas1 is extremely relevant for clinical practice. However, the important association between urinary calcium and sodium excretion was not emphasized. A study realized by Carbone et al2 found that approximately 1.2 mmol/L of calcium (to convert to milligrams per deciliter, multiply by 4) were excreted per 100 mmol/L of sodium (the conversion to milliequivalents per liter is a 1-to-1 conversion), and this relationship was independent of race. As a result, in subjects with a high sodium intake, a urinary calcium loss could generate a compensatory increase in serum parathyroid hormone levels. High serum parathyroid hormone levels have been associated with high body mass index,3 high blood pressure,4 and metabolic syndrome.5 The cardiovascular risk attributed to a high sodium intake may have other indirect mechanisms in addition to those traditionally described.
Premaor MO, Vanacour R, Furlanetto TW. Cardiovascular Disease, Sodium Intake, and Urinary Calcium Loss. Arch Intern Med. 2008;168(3):332. doi:10.1001/archinternmed.2007.97