The N-terminal sequence of the major erythropoietic factor of an anephric patient is identical to insulin-like growth factor I.
 The erythropoietic factors present in an anephric patient with nearly normal hematocrit were isolated from plasma by reversed-phase and gel permeation HPLC.
 The most active fraction was purified and the analysis of its N-terminal sequence was identical to the published sequence of the human insulin-like growth factor I (IGF I).
 Recombinant human IGF I had identical elution positions as the isolated erythropoietic factor on reversed-phase HPLC and the same molecular weight on gel permeation HPLC.
 Furthermore, hrIGF I stimulated erythroid colony formation in human bone marrow cultures as was previously shown for the isolated human erythropoietic factor.
 These results suggest that IGF I may replace erythropoietin as a stimulator of erythropoiesis in some patients with anemia and renal failure.
