Determining an Upper Reference Value for the Urinary Fluoride-Creatinine Ratio in Healthy Children Younger than 7 Years

Zohoori, Fatemeh; Maguire, Anne

doi:10.1159/000472263

Cited by 6 publications

(7 citation statements)

References 15 publications

(36 reference statements)

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“…A number of recent studies, mainly conducted in adults [Bashash et al, 2017[Bashash et al, , 2018Thomas et al, 2016] used spot urine samples to estimate fluoride exposure and its link with several health outcomes. Although the potential of spot urine samples to predict fluoride exposure has been examined in young children [Zohouri et al, 2006;Zohoori and Maguire, 2017], its appropriateness to estimate fluoride exposure in adults has not been examined and validated. Therefore, studies with adults are needed to provide more robust evidence on the suitability of spot urine samples to estimate fluoride exposure in this age group.…”

Section: Discussionmentioning

confidence: 99%

Biomarkers for the Assessment of Fluoride Exposure in Children

et al. 2020

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Due to practical difficulties in quantifying fluoride exposure, the ability of various biomarkers to predict it has been investigated previously. However, the results are inadequate for validation of their application and usefulness. This study aimed to investigate the association between contemporary/recent biomarkers of fluoride exposure and total daily fluoride intake (TDFI) of children with large differences in fluoride exposure through drinking water. TDFI was assessed in 61 healthy 4 to 5 years old children who provided at least one biomarker sample; 32 lived in a low-fluoride area (0.04 mgF/L) and 29 lived in a high-fluoride area (3.05 mgF/L). Validated questionnaires were administered to evaluate fluoride intake from diets (including water) and toothpaste ingestion. Daily urinary fluoride excretion (UFE) as well as fluoride concentrations in plasma, fasting whole saliva, hair and nails (toenails/fingernails) were evaluated and related to total fluoride exposure. TDFI, UFE and fluoride concentration of biomarkers were statistically significantly higher in the high-fluoride area than in the low-fluoride area. There was a strong statistically significant positive correlation between TDFI and: UFE (ρ=0.756, p<0.001); plasma fluoride concentration (ρ=0.770, p<0.001); toenail fluoride concentration (ρ=0.604, p<0.001). The statistically significant positive correlation between TDFI and fingernail fluoride concentration (ρ=470, p<0.001) as well as between TDFI and fasting whole saliva fluoride concentration (ρ=0.453, p=0.001) was moderate, whereas it was weak between TDFI and hair fluoride concentration (ρ=0.306, p=0.027). In conclusion, the current study confirmed the suitability of 24h urine samples for estimating F exposure in children. The strong correlations between TDFI and F in plasma and toenails also suggest these biomarkers may be considered for health risk assessments of fluoride in children who are susceptible to development of dental fluorosis. Sample preparation and analysis Urine samples collected over the 24h period were pooled for each participant, and the total volume was measured. Saliva samples were centrifuged at 1000 rpm (MSE Harrier 18/80, UK) for 2 min to separate any food debris [Martínez-Mier et al., 2011]. Each blood sample was centrifuged for 10 min at 1500 rpm and the plasma collected. Nail samples from each participant (finger-and toenails , separately) were weighed, and then surface contamination from the nail clippings was removed by sonication in distilled water for 15 min [Whitford, 2005]. The cleaned samples were dried at 95ºC and weighed again. Food samples were weighed and then homogenised using an industrial blender (Cookwork BL9292, UK). Water and urine samples were analysed directly using a F ion selective electrode (ISE, 720A series; Orion Research Inc., Boston, MA, USA) after addition of TISAB III [Martínez-Mier et al., 2011]. Food, toothpaste, plasma, whole saliva, hair and nail samples were analysed after overnight hexamethyldisiloxane-acid diffusion [Martínez-Mier et a...

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Section: Discussionmentioning

confidence: 99%

Biomarkers for the Assessment of Fluoride Exposure in Children

et al. 2020

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“…Among different biomarkers of F exposure, fasting plasma has been acknowledged as the gold standard. However, 24-h UFE can be considered as a more appropriate contemporary biomarker of F exposure due to being a non-invasive method and the fact that varying proportions of a given F dose are completely excreted with the urine in <24 h. Due to logistical challenges of collecting 24-h urine samples, spot urine collection, normalised for creatinine excretion using creatinine reference values, has been proposed as a simpler alternative to 24-h urine sample collection [Zohoori and Maguire, 2017]. In the present study, no spot urine sample was collected as a further potential F biomarker due to the lack of resources, including reference values for creatinine concentration in urine in our study population.…”

Section: Resultsmentioning

confidence: 99%

Biomarkers for the Assessment of Exposure to Fluoride in Adults

et al. 2021

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To monitor deficient or excessive intakes of biologically available fluoride (F), various biological samples have been tested for use as biomarkers of human exposure to F. Most such studies have concerned children and often have only involved measurement of F in 1 or 2 types of sample. The present study investigated the relationships of F concentrations in biomarkers of F exposure; including plasma, saliva, hair, finger- and toenails, and daily urinary F excretion (UFE) with the total daily F intake (TDFI) of adults. TDFI was assessed in 60 healthy adults, aged ≥20 years; 31 lived in a low-F water area (LFA, 0.04 mg F/L) and 29 in a high-F water area (HFA, 3.05 mg F/L) of Nigeria. All volunteers provided at least 1 biomarker sample from the above list and completed a questionnaire to evaluate F intake from the diet and toothpaste ingestion. TDFI, UFE and F concentrations of biomarkers were statistically significantly higher in the HFA than in the LFA. There were strong statistically significant positive correlations between TDFI and UFE (ρ = 0.730, p < 0.001); plasma F (ρ = 0.729, p < 0.001); fasting whole saliva F (ρ = 0.653, p < 0.001) and hair F (ρ = 0.603, p < 0.001). The statistically significant positive correlations between TDFI and fingernail F (ρ = 0.502, p < 0.001) and between TDFI and toenail F (ρ = 0.556, p < 0.001) were moderate. In conclusion, this study has indicated the usefulness of 24-h UFE as well as F concentration in plasma, fasting whole saliva and hair as biomarkers of contemporary or sub-chronic F exposure in groups of adults. However, they do not appear to have the necessary sensitivity to predict F exposure in individuals.

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“…Less than half (45%; n = 93) of the included studies reported the investigation of any relationship between fluoride intake and excretion. Of the studies [8, 9, 20–100] that investigated the intake/excretion relationship, the majority (30%; n = 28) reported the association between fluoride concentration of water and fluoride excretion, whereas only 18 studies (19%) reported the association between fluoride intake and fluoride excretion (Table 4).…”

Section: Resultsmentioning

confidence: 99%

“…However, when monitoring inadvertent F ingestion, such as through swallowed toothpaste, or through community-based milk fluoridation programmes when participants receive a single fluoride dose at a particular time of day, it is important that more spot urine samples are collected to allow the most appropriate and accurate evaluation of the programme. Although creatinine-adjustment methods have been reported [20, 104] as an appropriate method for estimation of urine fluoride concentration of spot urine samples, and consequently urinary fluoride excretion, they have not been widely explored with different populations and intakes (i.e. different age groups, diet, etc).…”

Section: Discussionmentioning

confidence: 99%

The use of urinary fluoride excretion to facilitate monitoring fluoride intake: A systematic scoping review

et al. 2019

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BackgroundAs a recognised effective and economical agent for dental caries prevention, fluoride has been used in many different fluoridation schemes implemented across the world. Considering the narrow ‘dose-gap’ between the benefit of caries reduction and the risk of dental fluorosis, it is recommended that fluoride intake is monitored by measuring urinary fluoride excretion. The aim of this scoping review is to map the current literature/evidence on fluoride intake and excretion studies in relation to the study population, settings, type of study design, methodology, and analytical approach.MethodsEmbase/Ovid, MEDLINE/Ovid, CINAHL/EBSCO, Scopus/Elsevier were searched for relevant articles until April 2018. Studies were included if they reported intake and excretion of fluoride in healthy humans of all age groups. Findings were explored using a narrative synthesis to summarise studies characteristics and outcome measures.ResultsRemoval of duplicates from the originally 2295 identified records yielded 1093 studies of which 206 articles were included. Only 21.6% of the studies were conducted in children (<8-year-olds). Most studies (38.8%) used drinking water concentration as a proxy for fluoride intake, whereas only 11.7% measured fluoride intake from all sources. Of the 72 studies that measured dietary fluoride intake, only 10 reported the validity of the employed dietary assessment method. Only 14 studies validated the urine sample collection methods. No information on the validity of the employed analytical method was reported by the majority (64.6%) of studies. Only a small proportion (8.7%) of the included studies investigated the association between fluoride intake and excretion.ConclusionThe findings reveal much variability in terms of conducting the studies and reporting the findings, illustrating a high heterogeneity in data collection across settings and populations. Future studies should provide more detail on sampling technique, measurement protocols (including validation), and on clearly defining the relationship between intake and urinary excretion of fluoride.

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Determining an Upper Reference Value for the Urinary Fluoride-Creatinine Ratio in Healthy Children Younger than 7 Years

Cited by 6 publications

References 15 publications

Biomarkers for the Assessment of Fluoride Exposure in Children

Biomarkers for the Assessment of Fluoride Exposure in Children

Biomarkers for the Assessment of Exposure to Fluoride in Adults

The use of urinary fluoride excretion to facilitate monitoring fluoride intake: A systematic scoping review

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