Estimation of sodium excretion should be made as simple as possible, but not simpler: misleading papers and editorial on spot urines

A reduction in population salt intake is one of the most cost-effective measures to prevent cardiovascular disease [1, 2]. Two recent articles by O’Donnell et al. in the New England Journal of Medicine attempt to cast doubt on this important public health policy by claiming that a salt intake below 7.5 g/day was not associated with lower blood pressure and related to a higher cardiovascular events or total mortality based on the Prospective Urban Rural Epidemiology study [3, 4]. However, this claim is invalid because of methodological problems as well as errors in using a mathematical formula to estimate daily salt intake from spot urinary sodium.