Reticulocyte response to endogenous erythropoietin after renal transplantation

We determined in a prospective study reticulocyte counts and serum erythropoietin concentrations after renal transplantation in 37 recipients of renal allografts. Erythropoietin decreased in 35 patients out of 37 during surgery. Results concerning reticulocyte counts allowed us to define two groups of patients. Group 1: 33 patients had a reticulocyte peak before d29. Among them the reticulocyte peak followed the first Epo peak in 22 patients (1a) and occurred after several Epo peaks in 11 patients (1b). Patients of groups 1b had a serum creatinine level above 300 mumol/l at the time of the first Epo peak. Group 2: 4 patients with acute tubular necrosis had no reticulocytes peak before d29 despite one or several erythropoietin peaks. Post-operative erythropoietin reduction was not entirely explained by hemodilution or by per-operative blood transfusions. The erythropoietin peak appeared to be efficient only when creatinine at the time of the peak was under 200 mumol/l according to the inhibition of erythropoiesis during renal failure.