RED-BLOOD-CELL DENSITY DISTRIBUTION IN UREMIC PATIENTS ON ACETATE AND BICARBONATE HEMODIALYSIS

Renal anemia is the result of reduced erythropoietin (EPO) biosynthesis in the diseased kidney and also in part the result of a reduced life span of red blood cells (RBCs). An increase in density and a decrease in enzyme equipment (aspartate aminotransferase; GOT) of RBCs reflect cell age. In the following study, the density distribution (median density D50; determined by Percoll density gradients) and GOT activities of RBCs were measured in patients on acetate (HDA; n = 15) and bicarbonate (HDB; n = 51) hemodialysis. Hemoglobin (Hb) concentrations were: in the HDB group, 9.1 +/- 3.4 g/dl; in the HDA group, 6.2 +/- 1.2 g/dl, and, in a control (C) group of healthy persons, 14.0 +/- 1.5 g/dl. 14 HDB patients with severe anemia received EPO therapy during 1 year. D50 were found as follows: group C, 1.0674 +/- 0.0016 g/ml; HDB, 1.0674 +/- 0.0015 g/ml, and HDA, 1.0660 +/- 0.0012 g/ml (HDA vs. group C: p < 0.05; HDA vs. HDB: p < 0.05. D50 were elevated in the subgroups of HDA and HDB patients with severe anemia (Hb < 8 g/dl). During activated erythropoiesis by EPO therapy, D50 decreased from 1.06739 +/- 0.0015 to 1.0656 +/- 0.0014 g/ml. The GOT activities in RBCs demonstrated a rejuventation of the RBC population in the HDB group (6.4 +/- 2.5 U/g Hb) and HDA group (5.9 +/- 3.1 U/g Hb) compared to group C (3.9 +/- 1.3 U/g Hb). The enlarged enzyme decrease of RBCs in the HDB group (0.553 +/- 0.171 U/g Hb/fraction) and HDA group (0.599 +/- 0.135 U/g Hb/fraction in comparison to group C (0.243 +/- 0.156 U/g Hb/fraction demonstrates the reduced life span of RBCs in uremia. HDA patients with Hb > 10 g/dl showed significantly larger enzyme decreases (1.134 +/- 0.533 U/g Hb/fraction) compared to HDB patients (0.399 +/- 0.199 U/g Hb/fraction; p < 0.005). This demonstrates an increased cell stress in HDA.