Abstract
The renal clearance of fluoride (CF) was studied in pentobarbital-anesthetized rats. Urine flow rate and chloride clearance, previously thought to be the main determinants of CF, were readily dissociated from CF. Neither the clearance of sodium nor the excretion of potassium correlated consistently with CF. In experiments designed to manipulate urinary pH, viz., the administration of NaHCO3 or NH4Cl, acetazolamide, and mannitol, CF correlated closely with urinary pH. At a urinary pH of 5.0-k96, CF/GFR averaged less than 5%, while at a urinary pH of approximately 7.6, mean CF/GFR exceeded 65%. The data suggest that 35-45% of the filtered fluoride is reabsorbed in the proximal tubule, regardless of the final urinary pH, while in acidosis the majority of fluoride reabsorption occurs in the distal nephron. The results suggest that the tubular reabsorption of fluoride is inversely related to tubular fluid pH. Fluoride reabsorption seems to occur by nonionic diffusion, apparently as hydrogen fluoride. Depending on local pH gradients, it may occur along the entire nephron.
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Fluoride pharmacokinetics during acid-base balance changes in man
Five healthy subjects were each given fluoride 3.0 mg (F) as sodium fluoride tablets on two occasions - during production of acid urine, induced by giving NH4Cl, and during production of alkaline urine obtained by giving NaHCO3. Frequent plasma and urine samples were taken up to 12 h and were
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Intake and metabolism of fluoride
The purpose of this paper is to discuss the major factors that determine the body burden of inorganic fluoride. Fluoride intake 25 or more years ago was determined mainly by measurement of the concentration of the ion in the drinking water supply. This is not necessarily true today because of
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Plasma and developing enamel fluoride concentrations during chronic acid-base disturbances
Mild acid-base disturbances were induced in rats for 30 days. These disturbances did not affect % ash of maxillary incisors or % P of the developing enamel from mandibular incisors. Total fluoride intake (food and water) among groups drinking fluoride-free water was constant. Nevertheless, average plasma and developing enamel fluroide
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Fluoride metabolism
Knowledge of all aspects of fluoride metabolism is essential for comprehending the biological effects of this ion in humans as well as to drive the prevention (and treatment) of fluoride toxicity. Several aspects of fluoride metabolism - including gastric absorption, distribution and renal excretion - are pH-dependent because the coefficient
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Environmental and physiological factors affecting dental fluorosis
In addition to differences in fluoride intake and possibly to calcium deficiency or malnutrition, there are several factors which may account for individual differences in the occurrence of dental fluorosis. Disorders in acid-base balance affect the renal handling of fluoride such that, in acidosis, the excretion rate is diminished and,
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Nutrient Deficiencies Enhance Fluoride Toxicity
It has been known since the 1930s that poor nutrition enhances the toxicity of fluoride. As discussed below, nutrient deficiencies have been specifically linked to increased susceptibility to fluoride-induced tooth damage (dental fluorosis), bone damage (osteomalacia), neurotoxicity (reduced intelligence), and mutagenicity. The nutrients of primary importance appear to be calcium,
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Fluoridation, Dialysis & Osteomalacia
In the 1960s and 1970s, doctors discovered that patients receiving kidney dialysis were accumulating very high levels of fluoride in their bones and blood, and that this exposure was associated with severe forms of osteomalacia, a bone-softening disease that leads to weak bones and often excruciating bone pain. Based on
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Fluoridated Water Causes Severe Dental Fluorosis in Children with Diabetes Insipidus
This section on Diabetes includes: • Fluoride & Impaired Glucose Tolerance • Fluoride & Insulin • Fluoride Sensitivity Among Diabetics • Fluoridated Water Causes Severe Dental Fluorosis in Children with Diabetes Insipidus • NRC (2006): Fluoride’s Effect on Glucose Metabolism Excessive exposure to fluoride causes a defect of the tooth enamel known as dental fluorosis. In
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Fluoridation of drinking water and chronic kidney disease: Absence of evidence is not evidence of absence
A fairly substantial body of research indicates that patients with chronic renal insufficiency are at an increased risk of chronic fluoride toxicity. Patients with reduced glomerular filtration rates have a decreased ability to excrete fluoride in the urine. These patients may develop skeletal fluorosis even at 1 ppm fluoride in the drinking water.
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Unheeded Warnings: Government Health Authorities Ignore Fluoride Risk for Kidney Patients
Despite the well known fact that individuals with kidney disease are at much higher risk of fluoride toxicity than the general population, there has yet to be any attempt in the United States, or any other country that practices mass-scale water fluoridation to determine the prevalence of fluoride-related effects (e.g.,
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