Erythropoietin (EPO) is produced primarily by the kidney and is the factor regulating red blood cell (RBC) production in mammals. Renal production of EPO is regulated by changes in oxygen availability. Under conditions of hypoxia, the level of circulating EPO increases, leading to increased production of RBCs. The overproduction of EPO may be an adaptive response associated with conditions that produce tissue hypoxia, such as living at high altitude, chronic obstructive pulmonary disease, cyanotic heart disease, sleep apnea, high-affinity hemoglobinopathy, smoking, or localized renal hypoxia. In other instances, excessive EPO levels result from production by neoplastic cells. Cases of increased EPO production and erythrocytosis have been reported for patients with renal carcinomas, benign renal tumors, Wilms' tumors, hepatomas, liver carcinomas, cerebellar hemangioblastomas, adrenal gland tumors, smooth muscle tumors, and leiomyomas. Deficient levels of EPO production are found in conjunction with certain forms of anemias. These include anemia of renal failure and end-stage renal disease, anemias of chronic disorders, chronic infections, autoimmune diseases, rheumatoid arthritis, AIDS, malignancies, anemia of prematurity, anemia of hypothyroidism, and anemia of malnutrition.
Swiss-Prot Accession Number: P01588