Characteristics of Iron Dextran Utilization in Man

Abstract

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.

Anemia as a Presenting Manifestation of Giant Cell Arteritis

“…In addition to complete blood counts, hcinatologic studies included reticulocyte count, serum iron, total iron binding capacity (TIBC), and bone marrow aspiration. Additional studies included the determination of cryoglobulins, cryofibrinogens, cold agglutinins, direct and indirect Coombs tests, urinary Bence-Jones protein, quantitative immunoglobulin by the gel diffusion plate technic, and iron dextran utilization (5) .…”

“…T h e patient was given 200 mg of labeled iron tlextran, with only 257' citili&-ihn in 14 (lays. This was interpreted as indicating a block in iron supply to the marrow as may be seen in chronic inflammatory states (5). Extensive studies for blood loss, infection and neoplastic disease were negative.…”

The Measurement of Reticuloendothelial Iron Release using Iron–Dextran

“…The proportion of iron utilized in erythropoiesis is greater when smaller doses are injected. The iron released from iron-dextran in the RE cell behaves in a similar manner (Henderson & Hillman, 1969) and the present study has made use of this in measuring RE iron release. Iron-dextran is a stable compound which is convenient for clinical use and a small dose was chosen to ensure satisfactory utilization.…”

“…The utilization of iron-dextran for haemoglobin formation is usually slower than that of transferrin bound iron because of its transit through the RE cell and because of the variable delay in its release into the plasma. Henderson & Hillman (1969) found 89-96% utilization of iron from [ 59Fe]iron-dextran administered intravenously after 10-14 days in patients with iron deficiency anaemia. In normal subjects utilization is not complete at 14 days and 35-62% of the administered iron is found in circulating red cells at that time (Davies et al, 1971).…”

The Metabolism of Intravenously Administered Iron‐Dextran

“…The iron taken up by the RE system in the form of either damaged red cells or irondextran is released into the plasma pool (Baird & Podmore, 1954;Noyes et a!, 1960) and appears to be more rapidly available than storage iron. It has been suggested that RE iron released by the breakdown of these compounds forms a 'pre-release pool' which reacts readily with transferrin or chelating agents (Lipschitz et al, 1971).Previous descriptions of [59Fe]iron-dextran clearance after an intravenous injection have been based on the assumption that its concentration is shown by the 59Fe activity remaining in the plasma (Henderson & Hillman, 1969). Davies et a1 (1971) have shown that the 59Fe plasma clearance curve after such an injection is, however, a complex function involving more than one component.…”