THE PHYSIOLOGIC AND CLINICAL SIGNIFICANCE OF ERYTHROPOIETIN

Abstract

Erythropoietin can be demonstrated in plasma of anemic animals and man by measuring the erythropoietic stimulating effect of the plasma or a heat-denatured extract of it on the incorporation of Fe59 into the red cells of the starved or hypophysectomized rat after injection of the plasma being tested. Activity of human plasma is lost to variable degrees when heat-denatured extracts are prepared. Plasma from anemic patients can be assayed without first extracting protein, thereby circumventing loss of activity coincident to extraction. Following transfusion of anemic patients, the high titer of erythropoietin in the plasma and urine decreases rapidly. No elevation of erythropoietin titer was found in the plasma of 7 patients with refractory anemia secondary to chronic renal disease. It appears that normal erythro-poiesis in man and animals is continuously regulated by erythropoietin.