The fractional urinary fluoride excretion in young children under stable fluoride intake conditions

Abstract

The purpose of this study was to determine the fraction of the total daily fluoride intake that is excreted through the urine (FUEF) of children aged 3-5 years under usual intake conditions. Participating children were residents of an area with a fluoride (F) concentration of 0.5-0.6 mg/L in their drinking water. Assessments were made on two successive 24-h periods on 20 children, measuring the total amount of fluoride ingested through liquid and food consumption, and from ingestion of fluoridated toothpaste (500 microg F/g), together with the determination of the amount of fluoride excreted through urine. Fluoride retention was also estimated assuming a constant average F fraction of 10% excreted through faeces. It was found that the average proportion of liquids, solid foods, and toothpaste to the daily fluoride intake (1.02-mg F/day on average) were 40.8, 34.6, and 24.5%, respectively. The average FUEF value was 35.5% (95% C.I.=31.7-39.3%), and the estimated fractional F retention was 54.5%. The present data suggest a slight relationship between FUEF values and the inverse of the daily fluoride dose (1/dose) (r=0.513; P=0.021). When the present results are combined with those from previous studies on F-retention and urinary excretion, the correlation between both FUEF and fractional retention and 1/dose are very strong and highly significant (r=0.98, P<0.0001, and r=-0.986, P<0.0001, respectively). A possible mechanism is suggested in order to explain this latter finding. The potential usefulness of the current FUEF value for the estimation of daily F intake (or dose) from urinary F excretion data is also discussed.

Determination of Fluoride Intake from Urinary Fluoride Excretion Data in Children Drinking Fluoridated School Milk

“…This is in agreement with other workers who similarly found that the fraction of fluoride excreted at low fluoride intake was higher than at higher levels of intake [McClure et al, 1945;Machle et al, 1942;Villa et al, 2000].…”

Total daily fluoride intake and fractional urinary fluoride excretion in 4‐ to 6‐year‐old children living in a fluoridated area: weekly variation?

“…ascorbic acid, ammonium chloride), can alter the rate of F absorption and excretion 27 , an estimate of body F retention in children would appear to be more valuable than estimation of F intake when considering dental fluorosis prevention. Several reports in the literature on FUFE in children report a range from 39 to 78% in infants and toddlers younger than 3 years 28-30 and 30 to 80% in children aged 3 to 7 years [12][13][14][15][16] ; indicating body F retention of 20% to 70% in children. The wide variation in F retention could be due to the physiological and dietary/ oral hygiene habit differences between the individuals and/or variations in the patterns of dietary/ oral hygiene habits within the individuals.…”

“…With urine being the prime metabolic pathway for absorbed F excretion F from the body, due to practical difficulties in collecting faeces in children, most F body burden studies have focused on measuring the fraction of ingested F excreted in urine, known as the fractional urinary F excretion (FUFE). These studies [12][13][14][15][16] have reported a wide variation in FUFE, ranging from 30% to 80% in children due primarily to methodological variations, participant age and between-population/ between-individual differences in dietary and oral hygiene patterns/habits. However, another explanation for these differences could be daily or weekly variations in dietary and oral hygiene patterns within an individual.…”

Total Fluoride Intake and Urinary Excretion in German Children Aged 3–6 Years

“…Pertinent evaluations of fluoride balance, i. e. the relationship of fluoride intake vs. fluoride excretion in small children and pre-schoolers, have been relatively scarce and results were conflicting. While in their studies of children 3-5 years of age, Villa et al [2000] found that the rate of urinary fluoride excretion averaged 35.5% of the amount ingested, the investigations of Brunetti and Newbrun [1983] and Zohouri and Rugg-Gunn [2000] in pre-school children indicated considerably higher urinary excretion rates of 80-85%.…”

“…Apart from solid and liquid foods which include drinking water and mineral water, determination of total intake nowadays needs to consider fluoride supplements, toothpaste and other preparations used for caries prevention. There are only few investigations into the fluoride intake of small children and pre-school children that include all these sources [Guha-Chowdhury et al, 1996;Rojas-Sanchez et al, 1999;Villa et al, 2000;Zohouri and Rugg-Gunn, 2000].…”