Urinary sodium-to-creatinine ratio as an indicator of gastric cancer risk.

The difficulties in the estimation of daily intake of sodium chloride in populations are discussed. Total daily output calculations are hindered by the difficulties investigators encounter in obtaining accurate 24-hour urine collections in field work situations. As an alternative, urinary sodium-to-creatinine ratios were investigated. Such ratios, which do not change significantly with circadian excretion rhythms, are useful indicators of the amount of sodium excreted in the urine. Preliminary observations in Colombian populations at high and low risk of gastric cancer indicated higher sodium excretion in the high-risk group. Loss of sodium by other means, especially perspiration, needs to be estimated in some other way.