Erythropoiesis after withdrawal of enalapril in post-transplant erythrocytosis

Erythropoiesis after withdrawal of enalapril in post-transplant erythrocytosis. Enalapril effectively decreases hematocrits in patients with postrenal transplant erythrocytosis (PTE). We studied the effect of enalapril withdrawal on erythropoiesis in 18 patients with PTE who had been treated for 13 ± 8 months. Hematocrit, reticulocyte count, plasma erythropoietin, and plasma insulin-like growth factor I were measured biweekly for six weeks. Red cell mass, plasma volume, transferrin saturation, and plasma angiotensin II were measured at withdrawal and six weeks later. Hematocrit increased by at least 0.04 in 13 patients (‘responders') but changed by -0.08 to 0.01 in five patients (‘nonresponders'). In the responder subgroup, hematocrit increased from 0.43 ± 0.05 to 0.51 ± 0.05 (P