Changes in blood and plasma volume during treatment with recombinant human erythropoietin.

18 chronic dialysis patients with renal anemia were examined before and after three months of regular treatment with recombinant human erythropoietin (EPO). All patients responded with an increase in hemoglobin concentration (cHb). The target cHb of 7.0 mmol/L was subsequently maintained by one subcutaneous injection a week, obviating the need of blood transfusions. The amount of circulating hemoglobin and the volume of erythrocytes increased, but the plasma volume simultaneously decreased, maintaining a constant blood volume. Although some of the individual blood volumes varied, the relation between circulating hemoglobin and the hemoglobin concentration still existed. We conclude that the hemoglobin concentration gives an accurate measure of the degree of anemia, and measurement of circulating hemoglobin is unnecessary during routine treatment of dialysis patients with EPO.