Estimated 24 h Urinary Sodium-to-Potassium Ratio Is Related to Renal Function Decline: A 6-Year Cohort Study of Japanese Urban Residents

Int J Environ Res Public Health. 2020 Aug 11;17(16):5811. doi: 10.3390/ijerph17165811.


The effect of the sodium-to-potassium ratio (Na/K) on renal function within the clinically normal range of renal function are limited. We investigated the effects of an estimated 24 h urinary Na/K (e24hUNa/K) on a 6-year renal function decline among 927 urban Japanese community dwellers with no history of cardiovascular diseases and medication for hypertension, diabetes, or dyslipidemia. We partitioned the subjects into quartiles according to the e24hUNa/K. The estimated glomerular filtration rate (eGFR) was calculated using the chronic kidney disease epidemiology collaboration (CKD/EPI) formula and renal function decline was defined as an absolute value at or above the third quartile of the eGFR decline rate. A multivariable logistic regression model was used for estimation. Compared with the first quartile of the e24hUNa/K, multivariable-adjusted odds ratios (ORs) for eGFR decline in the second, third, and fourth quartiles were 0.96 (95% confidence interval: 0.61-1.51), 1.06 (0.67-1.66), and 1.65 (1.06-2.57), respectively. These results were similar when the simple spot urine Na/K ratio was used in place of the e24hUNa/K. Apparently healthy urban residents with an almost within normal range mean baseline eGFR and high e24hUNa/K ratios had an increased risk for a future decline in renal function. Reducing the Na/K ratio may be important in the prevention of chronic kidney disease in its early stage.

Keywords: estimated GFR; renal function; urinary sodium; urinary sodium-potassium ratio.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Cohort Studies
  • Disease Progression
  • Female
  • Glomerular Filtration Rate
  • Humans
  • Japan / epidemiology
  • Kidney / physiopathology*
  • Middle Aged
  • Potassium / urine*
  • Renal Insufficiency, Chronic / epidemiology*
  • Renal Insufficiency, Chronic / urine
  • Risk Factors
  • Sodium / urine*
  • Urban Population


  • Sodium
  • Potassium