Control of post-transplant erythrocytosis by enalapril

Objective: To assess the erythropoietin response in patients with erythrocytosis after renal transplantation who were treated with enalapril. Patients: Fourteen patients with stable renal transplants (creatinine clearance, 74.4 ± 24.6 mL/min) and a packed cell volume of 51% or more over six months and who had no other cause for their erythrocytosis. Methods: Patients were treated with enalapril for six months. Serum erythropoietin levels, creatinine clearance and packed cell volume were measured before and during the study; patients were reviewed each month. Results: All patients had erythropoietin levels inappropriate for their packed cell volume. After six months' therapy with enalapril their mean erythropoietin concentration of 21.3 ± 5.0 U/L fell to 7.4 ± 1.3 U/L (P< 0.02) although the concentration increased in two patients. The mean packed cell volume fell from 52.7% ± 0.5% to 44.4% ± 1.0% (P< 0.0001). There was no change in renal function. Conclusion: Low-dose enalapril controls post-transplant erythrocytosis, at least in part, by lowering serum erythropoietin levels.