EPO (erythropoietin) is a glycoprotein hormone that serves as the primary regulator of red blood cell production and maintenance of physiological erythrocyte mass 1. The hormone is predominantly produced by specialized renal cells, with production rates determined by oxygen demands relative to oxygen supply 1. EPO expression is regulated by hypoxia-inducible factors (HIFs), particularly HIF-1, which bind to consensus sequences in the EPO gene enhancer under hypoxic conditions 23. Mechanistically, EPO binds to its homodimeric receptor (EPOR) on erythroid progenitors, triggering receptor dimerization and activation of intracellular antiapoptotic proteins, kinases, and transcription factors 34. This signaling pathway promotes erythroid progenitor expansion and terminal maturation while preventing apoptosis 5. Clinically, recombinant human EPO has proven highly effective in treating anemia associated with chr7 renal failure and shows promise in other anemic conditions 13. Recent evidence suggests EPO may have extraerythropoietic functions, including neuroprotective and anti-inflammatory properties, though clinical significance remains under investigation 53. Disease associations include familial erythrocytosis and diabetic complications, with certain EPO gene polymorphisms linked to diabetic retinopathy risk 6.