Use of a Chelating Agent for Accelerating Excretion of Radio-Iron

Abstract

Summary

1. Excretion of parenterally administered radio-iron is approximately 5 to 10 times as great in feces as in urine. The rate of excretion varies with the location of the tracer within the various iron pools in the body, (for example, cells, liver, reticulo-endo-thelial system, etc.). This is illustrated by high plasma levels of radio-iron, associated with high excretory rates in feces and urine. Fifty-five days after injection of tracer iron there is a second maximum in excretory rate which can be shown to correspond with a loss of radio-iron from the largest pool, the circulating erythrocytes. When “Fe-3 Specific” is administered intraperitoneally to animals which have been given iron 59, there is a prompt and marked increase in both the urinary and fecal excretory rates by a factor of 2 to 2.5. 2. The addition of “Fe-3 Specific” to the diet of rats causes an increase in the fecal and urinary excretion of intravenously administered radio-iron by approximately a factor of 2. 3. When labelled iron and “Fe-3 Specific” are fed simultaneously, a marked increase in urinary excretion of the tracer occurs. However, the amount found in feces is nearly the same as in controls. Thus the decrease in net retention resulted primarily because of increased urinary excretion. 4. Feeding as much as 9.6 g of “Fe-3 Specific” to animals at a rate of 400 mg per day, was not associated with any change in hematocrit nor any grossly observable abnormality in the animals.