Twenty‐four‐Hour Urinary Potassium Excretion, But Not Sodium Excretion, Is Associated With All‐Cause Mortality in a General Population

BACKGROUND Few studies have examined the relationship between accurate monitoring of sodium or potassium consumption and mortality. We aimed to investigate the association between 24-hour urinary sodium or potassium excretion and ≈30-year mortality in a Japanese population using 24-hour urine collection. METHODS AND RESULTS We enrolled a total of 1291 participants, aged 21 to 85 years, who underwent health checkups, including a blood test and 24-hour urine collection. They were followed up for 27.5±9.9 years by December 31, 2015, and the final follow-up rate was 95.8%. Cox proportional hazards regression analysis was used to assess the association between 24-hour urinary sodium or potassium excretion and all-cause mortality. At baseline, the mean 24-hour urinary sodium and potassium excretions were 5.80±2.28 g/d and 1.85±0.82 g/d, respectively. There were 631 deaths during the follow-up. The cumulative survival rate was significantly decreased in the lowest quartile compared with the other higher groups. In the Cox proportional hazard model after adjustment for age and sex, 24-hour urinary potassium excretion, but not sodium excretion, was inversely associated with all-cause mortality. We divided the 24-hour urinary potassium excretion levels into quartiles. After adjustment for confounding factors, the hazard ratio of all-cause mortality in the highest quartile of 24-hour urinary potassium excretion versus the lowest was 0.62 (95% confidence interval, 0.48-0.79; P<0.001). CONCLUSIONS The 24-hour urinary potassium excretion, but not sodium excretion, was significantly associated with all-cause mortality in the general population.