Renal Clearance of Fluoride.

Abstract

Fluoride in dog plasma was completely ultrafilterable through Visking membranes when tested using the centrifuge type apparatus. In dogs with a normal water load, the average renal fluoride clearance was 2.7 ml/ minute. Fluoride clearance was more rapid than that of simultaneously measured Na or Cl clearances or urine flow. During mannitol diuresis, fluoride was cleared at a higher rate than was Na, Cl or phosphate. Though fluoride clearance was greater than urinary flow, it varied directly with the flow under mannitol osmotic diuresis. Salt diuresis produced by intravenous infusion of hypertonic NaNO3 or Na2SO4 solutions did not affect fluoride excretion; fluoride clearance was increased following hypertonic NaCl infusion. Highest fluoride: creatinine clearance ratios were attained during fluoride infusion plus osmotic diuresis with hypertonic mannitol or NaCl. No evidence was obtained for tubular secretion of fluoride.