“…It has long been known that cobalt increases erythropoiesis in man and experimental animals ( 1,2,3,4), and that it achieves its erythropoietic effect by initiating erythropoietin formation( 5,6). The clinical effectiveness of testosterone therapy in various refractory anemias has led to investigations which suggest that one method by which this hormone promotes erythropoiesis is also by stimulating the elaboration of erythropoietin ( 7 ) .…”