Erythropoietin and hypertension.

Erythropoietin (Epo) is a glycoprotein hormone responsible for the control of the proliferation and differentiation of cells of erythroid lineage. Recombinant erythropoietin (rHuEpo) is widely used as a pharmacological agent for the treatment of the anaemia of renal failure. Efficacy of rHuEpo and its superiority over blood transfusions have been proven in large multicentre trials. The most important side-effect of the therapy is the increase of BP which is observed in approximately 30-35% of dialysis patients receiving rHuEpo. It appears that the haemodynamic resetting that occurs with partial correction of anaemia may be inappropriate resulting in an altered vascular resistance in relation to the cardiac output. This is in turn due to the combination of increased blood viscosity and loss of hypoxic vasodilatation. Both these factors, however, cannot account completely for the rise in vascular resistance, and therefore the possibility of a direct and/or hormonally-mediated vasopressor effect of rHuEpo has recently been raised. Moreover, scarce information exists on the possible involvement of endogenous erythropoietin in the pathogenesis of arterial hypertension and haematological disturbances observed in primary and some secondary forms of hypertension.