Acute Effects of Intravenous Iron on Oxidative Stress and Endothelial Dysfunction in Non-dialysis CKD

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.