Hematology

Erythropoietin song

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Erythropoietin

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Key points in this song10

Erythropoietin (EPO) is a glycoprotein hormone produced primarily by peritubular interstitial cells of the renal cortex in response to hypoxia, mediated via HIF-1α stabilization.
EPO stimulates differentiation and proliferation of erythroid progenitor cells (CFU-E) in the bone marrow by binding the JAK2-STAT5 signaling pathway.
In anemia of chronic kidney disease, EPO production is inappropriately low, resulting in normocytic, normochromic anemia treated with recombinant EPO (epoetin alfa) or darbepoetin.
Recombinant EPO therapy requires adequate iron stores; functional iron deficiency is a common cause of EPO hyporesponsiveness and must be corrected before or during therapy.
Target hemoglobin in CKD patients on EPO therapy is 10–11 g/dL; exceeding 13 g/dL increases risk of stroke, MI, and thromboembolism.
Paraneoplastic EPO overproduction occurs classically with renal cell carcinoma, hepatocellular carcinoma, and hemangioblastoma, causing secondary polycythemia.
Polycythemia vera features low EPO levels due to a constitutively activating JAK2 V617F mutation, distinguishing it from secondary polycythemia where EPO is elevated.
EPO is produced by the liver in the fetus, with the kidney taking over production postnatally; this explains preserved EPO in early hepatic disease.
High-altitude exposure increases EPO secretion via HIF-1α, leading to increased RBC mass, right-shifted oxygen-hemoglobin dissociation curve, and elevated 2,3-BPG.
Pure red cell aplasia is a rare complication of recombinant EPO therapy caused by anti-EPO antibody formation, presenting with severe anemia and absent reticulocytes.