In cardiac surgery, iron deficiency affects 37% of preoperative patients and is associated with more frequent preoperative and postoperative anemia. It is an independent risk factor for postoperative blood transfusion, even in the absence of preoperatively associated anemia It is currently recommended to seek iron deficiency preoperatively during the discovery of any microcytic anemia and to achieve iron substitution if found. And also to seek supplemental iron deficiency in all patients with cardiac insufficiency.