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Monitoring population sodium intake using spot urine samples: validation in a New Zealand population

Journal of Human Hypertension volume 28, pages 657–662 (2014)Cite this article

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Abstract

Although 24-h urine collection is widely considered the ’gold standard’ for estimation of population sodium intake, spot urine collection is increasingly used as a convenient and affordable alternative. We used four published formulae to convert spot urine sodium into estimates of 24-h sodium excretion in order to establish which (if any) formula would be suitable for use in the New Zealand population. A convenience sample of 101 healthy volunteers provided two spot urine samples and a 24-h urine collection. Two formulae (one proposed by the Pan American Health Organisation (PAHO) and one derived from INTERSALT data) were most accurate, and provided estimates of key population indicators (mean, range and proportion above nutrient reference values) that were close to those of the measured 24-h urine excretion. Estimates using these formula were in closer agreement with 24-h excretion than the other formulae estimates using the Bland–Altman method. We conclude that spot urine sampling is a suitable alternative to 24-h urine collection in population surveys when spot urine sodium results are converted into estimates of 24-h sodium excretion using either the PAHO or INTERSALT formulae. However spot urine is a poor predictor of 24-h urinary sodium excretion for individual assessment.

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Acknowledgements

We are grateful to the Health Research Council of New Zealand and the National Heart Foundation of New Zealand for funding this research. We would like to thank Debra McNamara (research nurse) for her valuable contribution to data collection, and the participants of the study.

Sources of Support: This study was funded by the National Heart Foundation of New Zealand. RM was supported by a Clinical Research Training Fellowship from the Health Research Council of New Zealand.

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Authors and Affiliations

  1. Department of Human Nutrition, University of Otago, Dunedin, New Zealand

    R McLean & J Mann

  2. Department of Preventive and Social Medicine, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand

    R McLean & S Williams

  3. Department of Medicine, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand

    J Mann

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Correspondence to R McLean.

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McLean, R., Williams, S. & Mann, J. Monitoring population sodium intake using spot urine samples: validation in a New Zealand population. J Hum Hypertens 28, 657–662 (2014). https://doi.org/10.1038/jhh.2014.10

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