In congenital iron-loading anemias, such as [beta]-thalassemia (major and intermedia) and congenital dyserythropoietic anemia I and II, but also in acquired forms such as myelodys-plastic syndrome types RA (refractory anemia) and RARS (RA with ringed sideroblasts), the diseased erythron
dysregulates iron homeostasis by inhibiting hepcidin synthesis, even in the presence of iron overload (134-140).
Erythrocyte progenitor Cells that develop in the erythron
from stem cells and are "committed" to developing into erythrocytes (as opposed to white blood cells or platelets).
Anemia is usually present early in life because of insufficient iron supply to the erythron
In systemic-onset juvenile chronic arthritis, high circulating concentrations of IL-6 have been shown to be associated with defective iron supply to the erythron
and microcytic anemia that responds to intravenous iron (23).
It is likely that at early stages of iron deficiency, before the development of anemia, the impaired iron supply to the erythron
produces transient bouts of iron-deficient erythropoiesis, which lead to a shift in the distribution of CHr to lower values and to the appearance of hypochromic cells.
Similarly, a low Tsat value accompanied by high ferritin levels may reflect iron deficiency, but could also be an indication of a dysequilibrium between iron storage, circulation, and the erythron
(often referred to as functional iron deficiency).
These diagnostic difficulties have led to efforts to develop clinical laboratory tests that are capable of measuring the functional iron availability at the site of Hb synthesis in the erythron
, especially the erythrocyte and its precursors.
Secondary hyperparathyroidism: Recent studies have found that high-turnover bone disease may affect the size of the erythron
, thereby contributing to anemia.
New tools for clinical evaluation of erythron
function in man.