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Is the fluoride/creatinine ratio of a spot urine sample indicative of 24-h urinary fluoride?

Lookup NU author(s): Dr Vida Zohoori, Emerita Professor Anne Maguire, Professor Paula Moynihan


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Objective: The main aim of this study was to determine how representative the fluoride/creatinine (F/Cr) ratio of a spot urinary sample is of the fluoride content of a 24-h urine sample in young children aged 12-36 months. Subsidiary objectives were to: (a) evaluate the use of 24-h urine samples in monitoring fluoride exposure and (b) estimate the retention of fluoride in very young children. Methods: Seven healthy children residing in a fluoridated area completed the study. Dietary information was obtained using a 3-day estimated food diary followed by an interview on the fourth day. Samples of foods and drinks were analysed for fluoride content. Ingestion of fluoride from toothpaste was also measured. A 24-h urine sample and a morning spot urine sample were collected from each child. Results: The mean age of the children was 32 months (range: 16-36 months). The mean total daily intake of fluoride was 0.71 (±0.41) mg or 0.05 (±0.02) mg/kg bodyweight, of which 37% came from the diet, the remainder being from toothpaste ingestion. None of the children used any other sources of fluoride such as fluoride tablets or fluoridated salt. The mean F/Cr ratio was 1.49 (±0.63) mg F/g creatinine. A positive correlation (Pearson's correlation = 0.76, P = 0.05) between fluoride excretion estimated using the F/Cr ratio in a morning spot urine sample and fluoride excretion in a 24-h urine sample was found. There was also a positive correlation (Pearson's correlation = 0.83, P = 0.02) between total daily fluoride intake and 24-h urinary fluoride excretion. Less than half (43%) of the total daily fluoride intake was retained in the body. Conclusions: The F/Cr ratio of a morning spot urine sample may be used to estimate mean 24-h urinary excretion of fluoride and therefore has potential application for larger-scale epidemiological studies where 24-h samples are impractical. Estimates of 24-h urinary fluoride excretion can be used to gauge fluoride exposure. Copyright © Blackwell Munksgaard 2006.

Publication metadata

Author(s): Zohouri FV, Swinbank CM, Maguire A, Moynihan PJ

Publication type: Article

Publication status: Published

Journal: Community Dentistry and Oral Epidemiology

Year: 2006

Volume: 34

Issue: 2

Pages: 130-138

ISSN (print): 0301-5661

ISSN (electronic): 1600-0528

Publisher: Community Dentistry and Oral Epidemiology


DOI: 10.1111/j.1600-0528.2006.00269.x

PubMed id: 16515677


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