Plasma erythropoietin in health and disease.

Erythropoietin is a hormone produced by the kidneys and by certain extrarenal tissues and released into the circulation in response to tissue hypoxia. Its study has provided new information about oxygen transport and bone marrow stem cell function and its determination in plasma can give valuable diagnostic clues as to the etiology and pathogenesis of anemias and polycythemias. The various methods used for such measurements are discussed, and it is recommended that the in vivo bioassay in polycythemic mice be utilized until a workable radioimmune assay has been perfected. The results with the use of this in vivo bioassay to measure plasma erythropoietin in patients with uncomplicated anemia, aplastic anemia, anemia of renal disease, anemia of chronic inflammatory or neoplastic disorder polycythemia vera, and secondary polycythemia are charted and their diagnostic significance discussed.