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Urinary sodium-to-potassium ratio and intake of sodium and potassium among men and women from multiethnic general populations: the INTERSALT Study.

  • Iwahori, Toshiyuki1, 2, 3
  • Miura, Katsuyuki4, 5
  • Ueshima, Hirotsugu4, 5
  • Tanaka-Mizuno, Sachiko6
  • Chan, Queenie7
  • Arima, Hisatomi8
  • Dyer, Alan R9
  • Elliott, Paul7
  • Stamler, Jeremiah9
  • 1 Department of Public Health, Shiga University of Medical Science, Shiga, Japan. [email protected] , (Japan)
  • 2 Graduate School of Science, Technology and Innovation, Kobe University, Hyogo, Japan. [email protected] , (Japan)
  • 3 Research and Development Department, Omron Healthcare Co., Ltd, Kyoto, Japan. [email protected] , (Japan)
  • 4 Department of Public Health, Shiga University of Medical Science, Shiga, Japan. , (Japan)
  • 5 Center for Epidemiologic Research in Asia, Shiga University of Medical Science, Shiga, Japan. , (Japan)
  • 6 Department of Medical Statistics, Shiga University of Medical Science, Shiga, Japan. , (Japan)
  • 7 MRC-PHE Centre for Environment and Health, Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK.
  • 8 Department of Preventive Medicine and Public Health, Fukuoka University, Fukuoka, Japan. , (Japan)
  • 9 Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
Published Article
Hypertension research : official journal of the Japanese Society of Hypertension
Publication Date
Oct 01, 2019
DOI: 10.1038/s41440-019-0263-1
PMID: 30996260


The Na/K ratio may be more strongly related to blood pressure and cardiovascular disease than sodium or potassium. The casual urine Na/K ratio can provide prompt on-site feedback, and with repeated measurements, may provide useful individual estimates of the 24-h ratio. The World Health Organization has published guidelines for sodium and potassium intake, but no generally accepted guideline prevails for the Na/K ratio. We used standardized data on 24 h and casual urinary electrolyte excretion obtained from the INTERSALT Study for 10,065 individuals aged 20-59 years from 32 countries (52 populations). Associations between the casual urinary Na/K ratio and the 24-h sodium and potassium excretion of individuals were assessed by correlation and stratification analyses. The mean 24-h sodium and potassium excretions were 156.0 mmol/24 h and 55.2 mmol/24 h, respectively; the mean 24-h urinary Na/K molar ratio was 3.24. Pearson's correlation coefficients (r) for the casual urinary Na/K ratio with 24-h sodium and potassium excretions were 0.42 and -0.34, respectively, and these were 0.57 and -0.48 for the 24-h ratio. The urinary Na/K ratio predicted a 24-h urine Na excretion of <85 mmol/day (the WHO recommended guidelines) with a sensitivity of 99.7% and 94.0%, specificity of 39.5% and 48.0%, and positive predictive value of 96.3% and 61.1% at the cutoff point of 1 in 24 h and casual urine Na/K ratios, respectively. A urinary Na/K molar ratio <1 may be a useful indicator for adherence to the WHO recommended levels of sodium and, to a lesser extent, the potassium intake across different populations; however, cutoff points for Na/K ratio may be tuned for localization.

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