Urinary spot samples are a promising method for the biomonitoring of micronutrient intake in children. Our aim was to assess whether urinary spot samples could be used to estimate the 24-h urinary excretion of potassium, phosphate, and iodine at the population level.
A cross-sectional study of 101 children between 6 and 16 years of age was conducted. Each child collected a 24-h urine collection and three urinary spot samples (evening, overnight, and morning). Several equations were used to estimate 24-h excretion based on the urinary concentrations of each micronutrient in the three spot samples. Various equations and spot combinations were compared using several statistics and plots.
Ninety-four children were included in the analysis (mean age: 10.5 years). The mean measured 24-h urinary excretions of potassium, phosphate, and iodine were 1.76 g, 0.61 g, and 95 µg, respectively. For potassium, the best 24-h estimates were obtained with the Mage equation and morning spot (mean bias: 0.2 g, correlation: 0.27, precision: 56%, and misclassification: 10%). For phosphate, the best 24-h estimates were obtained with the Mage equation and overnight spot (mean bias: − 0.03 g, correlation: 0.54, precision: 72%, and misclassification: 10%). For iodine, the best 24-h estimates were obtained with the Remer equation and overnight spot (mean bias: − 8 µg, correlation: 0.58, precision: 86%, misclassification: 16%).
Urinary spot samples could be a good alternative to 24-h urine collection for the population biomonitoring of iodine and phosphate intakes in children. For potassium, spot samples were less reliable.
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We thank the participants and their parents for taking part in the study, René Tabin, Bernard Genin and Michel Russo for the help with the recruitment of the study participants, and Michel F. Rossier and Marie-France Rudaz for the laboratory analyses.
This work was funded by the Swiss Federal Food Safety and Veterinary Office (FSVO) (funding reference number 5.15.03). The funder had no role in the protocol development, data collection, data analysis, or interpretation.
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The authors declare no conflicts of interest.
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Rios-Leyvraz, M., Bochud, M., Benzi Schmid, C. et al. Population biomonitoring of micronutrient intakes in children using urinary spot samples. Eur J Nutr 59, 3059–3068 (2020). https://doi.org/10.1007/s00394-019-02144-9
- Urinary excretion
- Urinary spots