The urinary fluoride/creatinine ratio (UF/Cr) in a spot urine sample could be a useful systemic F exposure monitoring tool. No reference value for UF/Cr currently exists, therefore this study aimed to establish an upper reference value for a UF/Cr, corresponding to excessive systemic F exposure, i.e., >0.07 mg F/kg body weight (b.w.)/day, in children. Subsidiary aims were to examine the relationship between (i) total daily F intake (TDFI) and 24-h urinary F excretion (DUFE); (ii) DUFE and UF/Cr, and (iii) TDFI and UF/Cr. Simultaneously collected TDFI, DUFE, and urinary creatinine (UCr) data in children <7 years were taken from UK studies conducted from 2002 to 2014 in order to calculate UF/Cr (mg/g) for each child. For the 158 children (mean age 5.8 years) included in the data analysis, mean TDFI and DUFE were 0.049 (SD 0.033) and 0.016 (SD 0.008) mg/kg b.w./day, respectively, and the mean UF/Cr was 1.21 (SD 0.61) mg/g. Significant (p < 0.001) positive linear correlations were found between TDFI and DUFE, DUFE and UF/Cr, and TDFI and UF/Cr. The estimated upper reference value for UF/Cr was 1.69 mg/g; this was significantly (p = 0.019) higher than the UF/Cr (1.29) associated with optimal F exposure (0.05-0.07 mg/kg b.w./day). In conclusion, the strong positive correlation between TDFI and UF/Cr confirms the strong association of these 2 F exposure variables and the value of a spot urine sample for prediction of TDFI (i.e., the most important risk factor in determining fluorosis occurrence and severity) in young children. Establishing an estimation of an upper reference value of 1.69 mg/g for UF/Cr in spot urine samples could simplify and facilitate their use as a valuable tool in large epidemiological studies.

Keywords:
Fluoride, Creatinine, Reference value, Child, Urine
1.
Bones R, Taussky H: On the colorimetetric determination of creatinine by the Jaffe reaction. J Biol Chem 1951;158:581-591.
2.
Broffitt B, Levy SM, Warren JJ, Heller KE: Seasonal variation in fluoride intake: the Iowa fluoride study. J Public Health Dent 2004;64:198-204.
3.
Burt BA: The changing patterns of systemic fluoride intake. J Dent Res 1992;71:1228-1237.
4.
European Food Safety Authority: Scientific opinion of the panel on food additives and nutrient sources added to food. Sodium monofluorophosphate as a source of fluoride added for nutritional purposes to food supplements. EFSA J 2008;886:1-18.
5.
Garcia-Hoyos F, Barberia E, Garcia-Camba P, Varela M: Renal fluoride excretion in children following topical application of fluoride varnish. Eur J Paediatr Dent 2012;13:280-284.
6.
Garcia-Hoyos F, Silva CC, Barberia E: Renal excretion of fluoride after fluoride mouth rinses in children. Eur J Paediatr Dent 2014;15:35-38.
7.
Institute of Medicine: Dietary Reference Intakes for Calcium, Magnesium, Vitamin D, and Fluoride. Washington, National Academy Press, 1997.
8.
Kertesz P, Banoczy J, Ritlop B, Brody A, Peter M: The determination of urinary fluoride/creatinine ratio (Q) in monitoring fluoride intake. Acta Physiol Hung 1989;74:209-214.
9.
Levy SM, Broffitt B, Marshall TA, Eichenberger-Gilmore JM, Warren JJ: Associations between fluorosis of permanent incisors and fluoride intake from infant formula, other dietary sources and dentifrice during early childhood. J Am Dent Assoc 2010;141:1190-1201.
10.
Maguire A, Zohouri FV, Hindmarch PN, Hatts J, Moynihan PJ: Fluoride intake and urinary excretion in 6- to 7-year-old children living in optimally, sub-optimally and non-fluoridated areas. Community Dent Oral Epidemiol 2007;35:479-488.
11.
Martínez-Mier EA, Cury JA, Heilman JR, Katz BP, Levy SM, Li Y, Maguire A, Margineda J, O'Mullane D, Phantumvanit P, Soto-Rojas AE, Stookey GK, Villa A, Wefel JS, Whelton H, Whitford GM, Zero DT, Zhang W, Zohouri V: Development of gold standard ion-selective electrode-based methods for fluoride analysis. Caries Res 2011;45:3-12.
12.
Omid N, Maguire A, O'Hare WT, Zohoori FV: Estimation of daily dietary fluoride intake: 3-day food diary vs 2-day duplicate plate. Br J Nutr 2015;114:2103-2109.
13.
Omid N, Maguire A, O'Hare WT, Zohoori FV: Total daily fluoride intake and fractional urinary fluoride excretion in 4- to 6-year-old children living in a fluoridated area: weekly variation? Community Dent Oral Epidemiol 2017;45:12-19.
14.
O'Mullane DM, Baez RJ, Jones S, Lennon MA, Petersen PE, Rugg-Gunn AJ, Whelton H, Whitford GM: Fluoride and oral health. Community Dent Health 2016;33:69-99.
15.
Oski F, DeAngelis C, Feigin R, McMillan J, Washaw J: Principles and Practice of Pediatrics, ed 2. Philadelphia, Lippincott, 1994.
16.
Remer T, Neubert A, Maser-Gluth C: Anthropometry-based reference values for 24-h urinary creatinine excretion during growth and their use in endocrine and nutritional research. Am J Clin Nutr 2002;75:561-569.
17.
Sethuram R, Kiran TSU, Weerakkody ANA: Is the urine spot protein/creatinine ratio a valid diagnostic test for pre-eclampsia? J Obstet Gynaecol 2011;31:128-130.
18.
Szekely M, Banoczy J, Fazakas Z, Hobai S, Villa A: A comparison of two methods for the evaluation of the daily urinary fluoride excretion in Romanian pre-school children. Community Dent Health 2008;25:23-27.
19.
Villa A: A new method for determining fluoride urinary excretion in pre-school children populations (in Spanish). Odontol Chil 1994;42:28-31.
20.
Villa A, Anabalon M, Zohouri V, Maguire A, Franco AM, Rugg-Gunn A: Relationships between fluoride intake, urinary fluoride excretion and fluoride retention in children and adults: an analysis of available data. Caries Res 2010;44:60-68.
21.
Waterhouse C, Taves D, Munzer A: Serum inorganic fluoride: changes related to previous fluoride intake, renal function and bone resorption. Clin Sci 1980;58:145-152.
22.
Whitford GM: Metabolism and Toxicity of Fluoride. Basel, Karger, 1996.
23.
Wong MCM, Glenny AM, Tsang BWK, Lo ECM, Worthington HV, Marinho VCC: Topical fluoride as a cause of dental fluorosis in children. Cochrane Database Syst Rev 2010;1:CD007693.
24.
World Health Organization: Monitoring of renal fluoride excretion in community preventive programmes on oral health (Marthaler TH, ed). Geneva, World Health Organization, 1999.
25.
World Health Organization: Basic methods for assessing renal fluoride excretion in community prevention programmes for oral health Geneva, World Health Organization 2014.
26.
Yévenes I, Henández B, Ramos A, Jara M, Wolfenson P, Petrasic L: Fluoride intake in preschoolers from two different communes in Santiago, Chile. Rev Odonto Ciênc 2010;25:239-244.
27.
Zohoori FV, Walls R, Teasdale L, Landes D, Steen IN, Moynihan P, Omid N, Maguire A: Fractional urinary fluoride excretion of 6-7-year-old children attending schools in low-fluoride and naturally fluoridated areas in the UK. Br J Nutr 2013;109:1903-1909.
28.
Zohouri FV, Swinbank CM, Maguire A, Moynihan PJ: Is the fluoride/creatinine ratio of a spot urine sample indicative of 24-h urinary fluoride? Community Dent Oral Epidemiol 2006;34:130-138.
© 2017 S. Karger AG, Basel
2017
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.