Urinary excretion of calcium (Ca), magnesium (Mg), phosphorus (P), iodine and fluoride is used to assess their statuses and/or the existence of metabolic abnormalities. In the United Arab Emirates (UAE), the urinary concentration of these minerals among children have not been documented.
Materials and methods
A cross-sectional study, including 593 subjects (232 boys and 361 girls), was conducted among healthy 6 to 11-year-old Emirati children living in Dubai. Non-fasting morning urine samples and anthropometrical measurements were collected and analyzed. Results were expressed as per mg of creatinine (Cr).
On average, estimated Cr excretion was 17.88±3.12 mg/kg/d. Mean urinary Ca/Cr, Mg/Cr and P/Cr excretions were 0.08±0.07 mg/mg, 0.09±0.04 mg/mg, and 0.57±0.26 mg/mg respectively. Urinary excretion of Ca, Mg and P were found to decrease as age increased. Urinary excretion and predicted intake of fluoride were lower than 0.05 mg/kg body weight per day. Surprisingly, more than 50% of the children were found to have urinary iodine excretion level above adequate.
The Emirati schoolchildren had comparable levels of urinary Ca, Mg and P excretion to other countries. The 95% percentile allows the use of the current data as a reference value for the detection of mineral abnormalities. Fluoride excretion implies that Emirati children are at low risk of fluorosis. The level of urinary iodine excretion is slightly higher than recommended and requires close monitoring of the process of salt iodization to avoid the harmful impact of iodine overconsumption.
*Full-text study online at https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0255195
Urinary fluoride measurement is the most useful biomarker to assess fluoride status [24, 61] as fluoride excretion is an indicator of fluoride intake . AI of fluoride falls within the range of 0.05–0.07 mg/kg body/day weight in children less than 12 years of age, while UL is set at 0.1 mg/kg body weight/day [63, 64]. About 81.5% of children had estimated intake below 0.05 mg/kg boy weight per day and no one had an intake above the UL. The estimated intake of 0.032±0.031 mg/kg/day (median of 0.021 mg/kg/day) was slightly higher than that of Lebanese (0.250 mg/g) , Kuwaiti (0.280–0.220 mg/g) , and Spanish children (0.26 mg/g–before the administration of mouth wash) . In general, fluoride intake depends on the fluoride content of water and water-based beverages [67, 68]. Walia et al. (2017) reported that 68.2% of bottled water is produced locally and contains about 0.07 mgF/l , a value 10 times lower than that recommended by US Public Health Service (USPHS), which is 0.7 mg/l . Moreover, in children, tea ingestion could be a good source of fluoride as well as the ingestion of fluoridated toothpaste. Fluoride ingestion was below 0.05 mg/kg body per day and it still remains to be understood whether this low level of fluoride (ingestion or in water) is involved in the development of dental caries, that is highly (~50%) common among UAE children [70, 71]. Dental caries is a common multifactorial oral disease that can affect different age groups , and fluoride was found to be effective in reducing the prevalence of this condition . It is reported that ‘fluoride in saliva and dental plaque works to prevent dental caries primarily through topical-remineralization of tooth surfaces’ .