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.