Polycythaemia is erythropoietin-independent after renal transplantation. 
Serum erythropoietin increased in 55 patients after transplantation.  The serum erythropoietin decreased when the haematocrit and haemoglobin reached high levels, indicating recovery of a feed-back control system.  Despite the diminution of erythropoietin, six patients demonstrated a state of erythrocytosis while the in vitro cultures of BFU-e revealed high sensitivity to the reduced doses of erythropoietin, using monocyte-free T-lymphocyte-depleted peripheral blood.  In polycythaemic transplanted patients it is possible that cellular interactions stimulate an early hyperproliferation of BFR-e with a greater erythropoietin sensitivity and a partial capacity to grow in the absence of erythropoietin.