[The transferrin receptor: its role in iron metabolism and its diagnosis utility]

Transferrin receptor is a key protein for the cellular uptake of transferrin iron. The highest number of transferrin receptors is on the surface of erythroblasts. The released iron is used for hemoglobinosynthesis. Regulation occurs at mRNA level depending on the intracellular iron concentration. The synthesis of ferritin and transferrin receptor are regulated in an opposite manner. Serum transferrin receptor is a truncated monomeric form of the cellular receptor. Most of the circulating receptors come from erythroid marrow precursors. Its level mirrors the total tissue receptor mass, it depends on the rate of erythropoiesis and on the iron status. Serum transferrin receptor is easily measured by Elisa methods but the lack of standardization triggers large differences in the results. Unlike ferritin, the concentration of serum transferrin receptors is unaffected in inflammatory diseases, infections, malignancies or cytolysis. In these conditions its measurement is particularly valuable for assessing an associated iron deficiency. It is a very useful tool for the diagnosis of different causes of anemia. In chronic renal failure serum transferrin receptor can predict whether patients will respond to rHu EPO therapy.