Microsoft Word - NEF336BF

Dr. C. A. Blau, University of Washington, School of Medicine, Division of Medical Genetics, RG-25, Seattle, WA 98195 (USA) Dear Sir, In the recent letter by Salvati et al. [1], no induction of fetal hemoglobin (HbF) was observed in patients with chronic renal failure treated with erythropoietin (epo). We would like to propose that HbF induction was not observed for at least 3 reasons. First, reports describing the induction of HbF by epo in vivo have used doses more than 10-fold higher than the average of 24-50 U/kg reported by the authors [2, 3]. Second, intermittent ery-thropoietic stimulation with epo is more effective than continuous stimulation in the induction of HbF [4]. Thus, the 3 times weekly schedule used by the authors would be anticipated to be less effective than less frequent schedules of administration. Third, for reasons that remain poorly defined, HbF induction with epo likely requires the coadministra-tion of iron [5]. Epo, administered using effective doses and schedules, is a potent inducer of HbF [2-6], and its potential therapeutic role in patients with disorders of globin chain synthesis is deserving of further study. References Salvati F, Strippoli P, Barchetti M, Scatizzi A: Effect on hemoglobin F synthesis by erythropoietin in patients with anemia of end-stage renal disease maintained by chronic hemodialy-sis. Nephron 1992;60:371. Al-Khatti A, Veith R, Papayannopoulou Th, Fritsh EF, Goldwasser E, Stamatoyannopoulos G: Stimulation of HbF synthesis by epo in baboons. N Engl J Med 1987;317:415-420. Al-Khatti A, Stamatoyannopoulos G: Modulation of HbF production by erythropoietin. Trans Assoc Am Physicians 1988;101:54-61. Blau CA, Constantoulakis P, Al-Khatti A, Spa-daccino E, Goldwasser E, Papayannopoulou Th, Stamatoyannopoulos G: Fetal hemoglobin in acute and chronic states of erythroid expansion. Blood 1993;81:227-233. Vichinsky E, Nagel RL, Shah M. Johnson R, Spadaccino E, Fabry MF, Mangahas L, Stamatoyannopoulos G: The stimulation of fetal hemoglobin by hrerythrυpoietin in sickle cell anemia: A double-blind study; in Stamatoyannopoulos G, Nienhuis AW (eds): The Regulation of Hemoglobin Switching. Baltimore, Johns Hopkins University Press, 1991, pp 394-402. Rodgers GP, Uyesaka N, Dover GJ, Noguchi CT, Nienhuis AW, Schechter AN: Further studies of the hematologic and rheologic effects of fetal hemoglobin induction in sickle cell patients by hydroxyurea; in Stamatoyannopoulos G, Nienhuis AW (eds): The Regulation of Hemoglobin Switching. Baltimore, Johns Hopkins University Press, 1991, pp 377-393.