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Effects of salt intake reduction by urinary sodium to potassium ratio self-monitoring method

Hypertension Research (2024)Cite this article

Abstract

Effective and feasible educational methods are needed to control salt intake. We performed a single-center, non-randomized controlled study to investigate the effectiveness and feasibility of self-monitoring using a urinary sodium/potassium (Na/K) ratio-measuring device in patients with difficulty in reducing salt intake. This study included 160 patients with hypertension, chronic kidney disease, or heart disease who were followed up in the outpatient clinic of the Dokkyo Medical University Nikko Medical Center. Urinary Na/K ratio measuring Na/K ratio meter were loaned for 2–6 weeks to the treatment (T) group (n = 80) and not to the patients in the control (C) group (n = 80). In the T group, patients were instructed to measure the urinary Na/K ratio at least three times a day and maintain a Na/K ratio below 2.0. Salt reduction education and home blood pressure measurement guidance continued in both groups. The mean device loan period in the T group was 25.1 days, the mean number of measurements was 3.0 times/day, and the proportion of patients achieving three measurements per day was 48.8% (39/80). Self-monitoring using the urinary Na/K ratio meter successfully reduced salt intake by −1.9 g/day at the second visit (p < 0.001) in the T group. In contrast, no change was observed over time in the C group. Self-monitoring using the urinary Na/K ratio meter successfully reduced salt intake in patients with difficulty reducing salt intake.

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Acknowledgements

MS designed the research and wrote the initial draft of the manuscript together with TY; TY conceived of the study and participated in its design and coordination and helped draft the manuscript; SK and NO helped draft the manuscript; YN, NB, TT, TS, AU, KK, AK, HS, and YN participated in data collection; MS performed statistical analysis; The authors express their gratitude to N. Yamakoshi, Y. Murakami, and K. Yoshizawa for their assistance with data entry and administrative support for this study. We would like to thank Editage (www.editage.jp) for English language editing.

Funding

This study was supported by Dokkyo Medical University, Project Research Grant (2015-09) to MS and YN, and Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan (No. 26350581) to TY.

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Authors and Affiliations

  1. Department of Cardiovascular Medicine and Nephrology, Dokkyo Medical University Nikko Medical Center, 145-1 Moritomo, Nikko, Tochigi, 321 -1298, Japan

    Masahiro Shimoyama, Shinya Kawamoto, Takashi Tomoe, Takushi Sugiyama, Asuka Ueno, Atsuhiko Kawabe & Takanori Yasu

  2. Department of Diabetes and Endocrinology, Dokkyo Medical University Nikko Medical Center, Nikko, Tochigi, Japan

    Yuki Nakatani, Nobuyuki Banba & Yasuko Nagashima

  3. Department of Cardiology, Dokkyo Medical University, Nikko Medical Center, Nikko, Tochigi, Japan

    Keijiro Kitahara, Naoyuki Otani & Hiroyuki Sugimura

Authors
  1. Masahiro Shimoyama
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  2. Shinya Kawamoto
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  13. Takanori Yasu
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Corresponding author

Correspondence to Shinya Kawamoto.

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The authors declare no competing interests.

Ethics

The study protocol was approved by the Ethics Committee of Dokkyo Medical University Nikko Medical Center (ethical license number Nikko 2015-09). This study was conducted in accordance with the “Declaration of Helsinki” by the World Medical Association and the Sports, Science and Technology and the Ministry of Health, Labor and Welfare (established on December 22, 2014, and partially revised on March 27, 2023). Informed consent was obtained from the patients through an opt-out system, and those who refused to provide consent were excluded.

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Shimoyama, M., Kawamoto, S., Nakatani, Y. et al. Effects of salt intake reduction by urinary sodium to potassium ratio self-monitoring method. Hypertens Res (2024). https://doi.org/10.1038/s41440-024-01655-1

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