Assessment of erythropoiesis activity during hemodialysis therapy by soluble transferrin receptor levels and ferrokinetic measurements

The erythropoietic activity (EA) and degree of erythropoiesis attained by p atients undergoing hemodialysis (HD) administered recombinant human erythro poietin (rHuEPO) were studied using ferrokinetic measurements and tests of soluble transferrin receptor (sTfR) levels, assessing which parameter is mo st useful for measurements in clinical practice. Plasma Iron 59 (Fe-59) cle arance (half-life [T-1/2]Fe-59), plasma iron turnover (PIT), erythron trans ferrin uptake (ETU), and erythrocyte Fe-59 incorporation were determined in 23 patients before and at 4 months after administration of rHuEPO. sTfR le vels, hematopoietic parameters, and iron metabolism parameters were measure d periodically. T-1/2 Fe-59 was shortened (P = 0.004), PIT and ETU were inc reased (P = 0.032 and P = 0.013, respectively), and the time taken by eryth rocytes to incorporate 80% of the Fe-59 administered was reduced from 9.6 t o 6.1 days. sTfR levels were increased by 15 days; this increase was signif icant (P < 0.05) at 30 days, reaching a maximum of 3.22 mg/dL at day 45. A positive correlation was seen between sTfR levels and hemoglobin (Hb) (P = 0.001), hematocrit (P = 0.001), and reticulocytes (P = 0.038) that was not found between ferrokinetic parameters and those evaluating efficient erythr opoiesis (P = 0.345 between ETU and Hb), In conclusion, EA is increased, sh own by ETU and sTfR level. sTfR levels correlate with the parameters that e valuate efficient erythropoiesis, and their measurement does not involve th e technical and/or ethical limitations of studies of ferrokinetics, making them the tool of choice in clinical practice for the evaluation of EA in pa tients undergoing HD administered rHuEPO. (C) 2001 by the National Kidney F oundation, Inc.