Abstract
The spot urinary sodium-to-potassium (Na/K) ratio is a simple measure of salt loading and has been shown to be associated with elevated blood pressure (BP) in middle-aged and older adults. This study aimed to evaluate the association between the spot urinary Na/K ratio and BP in 457 healthy adolescents aged 12–15 years in a school-based setting. The mean urinary Na/K ratio was 4.99 ± 2.76, and no significant difference was found between the boys and girls. When the participants were stratified based on urinary Na/K ratio quartile, age- and sex-adjusted systolic and diastolic BP gradually increased as Na/K ratio increased (systolic BP: 106.1, 106.9, 108.2, and 111.5 mmHg, Ptrend < 0.001; diastolic BP: 62.0, 62.4, 63.1, 64.3 mmHg, Ptrend = 0.022). The systolic and diastolic BP were more closely associated with urinary Na/K ratio than with Na and K levels, as well as estimated daily salt intake. In the multiple regression analysis, the urinary Na/K ratio was significantly associated with systolic BP (β = 0.144, P < 0.001) and diastolic BP (β = 0.114, P = 0.015) independent of potential confounding factors. An additional subgroup analysis revealed that the BP of the group with both high salt intake (≥8.5 g/day) and high Na/K ratio (≥6.60) was significantly higher than that of the group with high salt intake alone (systolic BP, 115.0 vs. 109.1 mmHg, P < 0.001; diastolic BP, 66.0 vs. 62.5 mmHg, P = 0.017). These results suggest that the urinary Na/K ratio is associated with BP levels in healthy adolescents and may be useful for assessing salt loading and its effects on BP elevation.
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Data availability
All data used and analyzed to support the findings of this study are available from the corresponding author upon reasonable request.
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Funding
This work was supported by a grant from the JST COI (JPMJCE1302) and by 2013 and 2017 joint research grants from the Faculty of Health and Nursing Science, Wakayama Medical University.
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YZ and NM contributed to the study design, data collection, statistical analysis, interpretation, drafting, and final revision of the manuscript. MU contributed to the data collection and drafting of the manuscript. KM and MA contributed to the conception and design of the work and the final revision of the manuscript.
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All procedures performed in this study were approved by the Ethical Committee of Wakayama Medical University (approval Nos. G92 and 3173) and in accordance with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
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Zhang, Y., Miyai, N., Utsumi, M. et al. Spot urinary sodium-to-potassium ratio is associated with blood pressure levels in healthy adolescents: the Wakayama Study. J Hum Hypertens 38, 238–244 (2024). https://doi.org/10.1038/s41371-023-00883-1
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DOI: https://doi.org/10.1038/s41371-023-00883-1