The whole-body clearance of18F-fluoride injected intravenously into chronically uremic rats was found to proceed more slowly (7.6% of the dose in the first
hour, vs 28%) and to a lesser total amount (18.5% vs 46.7%) in 4 hrs than in normal rats of the same age. The concentration
of radiofluoride in the urine of uremies during the first hour was about 10% of that observed in normals. No changes in24Na and42K whole-body clearance rates were detected in this surgically-induced model of chronic uremia. Statistically significant elevations
in central compartment fluoride concentrations were observed 4 hrs after injection. Fluorine and calcium in bones of uremic
and normal animals were measured using Instrumental Neutron Activation Analysis techniques. The ratios μg F/mg Ca were highly
significantly greater in uremics (2.2±0.3 vs 1.1±0.3). These differences were primarily brought about by elevations in bone
fluoride rather than by decreases in calcium content of the uremic bone.