The balance between anemia, erythropoietin treatment, and elevated erythrocyte aggregation in patients with diabetic retinopathy and nephropathy: a hematologic point of view

Abstract

In their article on the implications of anemia as a risk factor for the progression of retinopathy and nephropathy in diabetic patients, Sinclair and colleagues (Am J Ophthalmol 2003;135:740–743) suggest that treating anemia with erythropoietin is beneficial in preventing the progression of these complications. However, it is well known that with the increase in red cell mass during treatment, a tendency toward a thrombotic state is inevitable. Diabetic patients are already prone to thrombosis, which is implicated in diabetic complications. I would like to refer to hemorheologic factors in the pathogenesis of diabetic complications. Blood rheology is complex and mainly determined by variables such as blood viscosity, hematocrit, erythrocyte aggregation (EA), and deformability.1,2 Hemorheologic factors, especially elevated EA, through their effects on microcirculation, have long been implicated in the pathogenesis of diabetic vascular complications, including retinopathy and nephropathy.3 The exact mechanisms of elevated EA in the pathogenesis of diabetic complications are not known. It was shown that as EA increases local blood flow and shear rate decrease; these events cause local acidosis and an increase in platelet aggregation that lead to endothelial cell damage.