The purpose of this study is to investigate the effects of acute intravenous iron administration on the endothelial function in non-dialysis Chronic Kidney Disease stages G3-G5 patients with anemia and iron deficiency, in relation to changes in oxidative and nitrosative status.

Inclusion Criteria:

• Chronic kidney disease stages G3-G5 (defined according to KDIGO criteria);
• Anemia (defined according to KDIGO criteria) and iron deficiency defined as serum ferritin < 100 ng/mL and/or TSAT < 20% (KDIGO).

Exclusion Criteria:

• contraindications of intravenous iron therapy: iron allergy, active infection, hemochromatosis, iron overload (serum ferritin > 500 ng/mL and/or transferrin saturation > 50%);
• treatment with iron and erythropoiesis-stimulating agents (at the time of recruitment and 6 months previously);
• active smoker status;
• antioxidant food supplements treatment in the last 3 months;
• clinically manifest bleeding;
• another cause of anemia (hemoglobinopathies, vitamin B12 and/or folic acid deficiency suggested by the megaloblastic peripheral blood smears's appearance, multiple myeloma and other paraproteinemias);
• severe anemia (Hb < 7 g/dl);
• baseline FMD < 7% (the existence of atherosclerosis which limits arterial reactivity);
• cancer (currently or in the past 6 months);
• hepatopathies (increased serum transaminases ≥ 3 x normal value) or hepatic impairment ≥ grade Child B;
• autoimmune disorders or significant inflammation (as defined by C-reactive protein > 5 mg/L);
• pregnancy or lactation;
• participation in other clinical trials over the upast 3 months;
• patient unwillingness.