Erythrokinetics. IV. The Plasma Iron Turnover as a Measure of Erythropoiesis

Abstract

Experimental and clinical studies have been performed to define more clearly the significance of the plasma iron turnover. It has been shown that the plasma iron turnover is not affected by the rate of red cell destruction and to only a limited extent by increased body stores. It does, however, reflect the degree of erythroid marrow activity and is a sensitive indicator for measuring changes in such activity. A series of 85 studies in normal subjects and in patients with various hematologic disorders were carried out to define the range of response with anemia and to assess the clinical value of the plasma iron turnover as an index of erythropoiesis. In states of marrow hyperfunction it is increased from 3 to 6 times normal and may be depressed to approximately half normal with marrow hypofunction. The plasma iron turnover is increased with marrow dyspoiesis. This increase is a measure of total erythropoiesis and does not indicate the production of viable red cells.

Iron Metabolism in Scurvy with Special Reference to Erythropoiesis*

“…One last point relates to the significance of the siderosis which was a major feature in the Bantu subjects studied. This association, which has also been observed by other workers (Schulz and Swanepoel, 1962) seemed to be more than fortuitous since the degrees of iron overload present were greater than would be expected in a hospital population of comparable age structure (Bothwell and Isaacson, 1962). It has been suggested that persons with siderosis living on a borderline diet may be precipitated into clinical scurvy as a result of irreversible oxidation of available ascorbic acid by the excessive deposits of ferric iron.…”

“…Although the present investigation was designed primarily to study iron metabolism in scurvy, the results obtained give some insight into the pathogenesis of anaemia in this condition. In the subjects studied, erythroid marrow activity was in the range which would be expected as a result of acute anaemia (Bothwell et al, 1957) and both in-vivo and in-vitro studies suggested that haemoglobin formation was normal. The anaemia present in these subjects must therefore have been the result of a degree of haemolysis and/or haemorrhage greater than the marrow's capacity to respond.…”

“…Plasma iron turnovers were carried out as described previously (Bothwell, Hurtado, Donohue and Finch, 1957). The percentage of injected s9Fe which subsequently reappeared in circulating red cells was measured in several subjects.…”

“…Haemin was crystallized by the method of Labbe and Nishida (1957). In order to correct for the incomplete recoveries obtained with this technique a solution of pure haemoglobin labelled with 55Fe was added to the 59Fe haemolysates at the beginning of the procedure and the washed haemin crystals were finally digested, electroplated on to copper discs and counted for 55Fe and 59Fe using methods previously described (Bothwell et al, 1957). In this way it was possible to calculate the percentage of 59Fe-haem in the original haemolysate.…”

“…The frequency of iron overload was confirmed by carrying out liver biopsies on 12 subjects after recovery. Siderosis was regarded as severe in 11 of them, using the criteria of Bothwell and Isaacson (1962).…”