 Patients under hemodialysis treatment are mostly treated by erythropoietin EPO through erythropoiesis stimulating agents ESA. The objective of ESA treatments is to maintain the hemoglobin level in a therapeutic target around 11gdl. The EPO dose that is necessary to reach this target depends on numerous and imbricated factors such as age, associated pathologies, iron status, inflammation. As of today, there is no marker to predict the EPO response and Hemoglobin Hb level is currently the only and late tool to assess the efficacy. 