Long-term therapy for postrenal transplant erythrocytosis with ACE inhibitors: efficacy, safety and action mechanisms.

SUBJECTS AND METHODS: Eleven patients with postrenal transplant erythrocytosis were treated with angiotensin-converting enzyme inhibitors for 18 months.
RESULTS: Indices of red blood cell production and destruction, renal function and kalemia were followed-up during the treatment. Angiotensin-converting enzyme inhibitors (ACEi) led to a progressive and significant fall in hemoglobin and hematocrit compared to the basal values at every time interval considered with a maximum reduction at 12th month for hemoglobin ( 17.04 +/- 0.21 vs. 15.10 +/- 0.42 g/dl, p < 0.0001) and at the 6th month for hematocrit (53.74 +/- 0.56 vs. 45.7 +/- 1.19 %, p < 0.0001). Serum erythropoietin levels were reduced significantly after the first month of therapy (13.56 +/- 2.7 vs. 7.48 +/- 1.6 mUI/dl, p < 0.05) after which no further variations were recorded. In the course of ACEi therapy, there was an inverse correlation between percentage reduction in erythropoietin values and those of hemoglobin emerged (r = 0.24, p < 0.05) and hematocrit (r = 0.39, p < 0.01). Indices of red blood destruction including haptoglobin, bilirubin and lactic dehydrogenase, were unaffected by ACE inhibitors treatment, as was creatininemia and kalemia. Treatment was well tolerated by all patients who completed the study without major adverse side-effects. No patient required phlebotomy and no thromboembolic event occurred during angiotensin-converting enzyme therapy.
CONCLUSIONS: Our results suggest that angiotensin-converting enzyme inhibitors are a safe and effective long-term therapy of postrenal transplant erythrocytosis. These agents decrease the erythropoietin synthesis but this effect is not the sole mechanism by which angiotensin-converting enzyme inhibitors act in postrenal renal transplant erythrocytosis.