Characteristics of Iron Dextran Utilization in Man

The major portion of iron dextran iron becomes available to the erythroid marrow only after uptake and release of ionic iron by the reticuloendothelial system. With large intravenous infusions, (1000-2000 mg.), the rate of removal of the iron dextran complex from plasma is enough to supply the marrow with more than 200 mg. of iron/day. However, in the present studies the observed rate of iron delivery to the erythroid marrow was far below this level. Although iron supply immediately after infusion was sufficient to permit marrow production to rise to 4-6 times normal, this was maintained for less than two weeks. With time, reticuloendothelial iron dextran stores became less available, the serum iron level fell and marrow production was restricted to levels below twice normal. In fact, large infusion doses and prolonged storage may have made a portion of the iron dextran stores completely unavailable. Thus, an iron deficient type of erythropoiesis appeared in some patients while iron dextran stores were still readily visible on examination of marrow stroma.