Population biomonitoring of micronutrient intakes in children using urinary spot samples
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.
KeywordsIodine Potassium Phosphate Urinary excretion Children Urinary spots
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.
Compliance with ethical standards
Conflict of interest
The authors declare no conflicts of interest.
- 7.Mente A, O’Donnell MJ, Dagenais G et al (2014) Validation and comparison of three formulae to estimate sodium and potassium excretion from a single morning fasting urine compared to 24-h measures in 11 countries. J Hypertens 32:1005–1014. https://doi.org/10.1097/HJH.0000000000000122 CrossRefPubMedGoogle Scholar
- 10.Polonia J, Lobo MF, Martins L et al (2017) Estimation of populational 24-h urinary sodium and potassium excretion from spot urine samples: evaluation of four formulas in a large national representative population. J Hypertens 35:477–486. https://doi.org/10.1097/HJH.0000000000001180 CrossRefPubMedGoogle Scholar
- 12.Montenegro-Bethancourt G, Johner SA, Stehle P et al (2015) Iodine status assessment in children: spot urine iodine concentration reasonably reflects true twenty-four-hour iodine excretion only when scaled to creatinine. Thyroid 25:688–697. https://doi.org/10.1089/thy.2015.0006 CrossRefPubMedGoogle Scholar
- 14.Haldimann M, Bochud M, Burnier M et al (2015) Prevalence of iodine inadequacy in Switzerland assessed by the estimated average requirement cut-point method in relation to the impact of iodized salt. Public Health Nutr 18:1333–1342. https://doi.org/10.1017/S1368980014002018 CrossRefPubMedGoogle Scholar
- 20.World Health Organization (2012) Guideline: Potassium intake for adults and children. World Health Organization (WHO), GenevaGoogle Scholar