Effect of Intravenous Iron (Ferinject®) on Exercise Capacity and Quality of Life of Stable COPD Patients

Inclusion Criteria: * Diagnosis of chronic obstructive pulmonary disease according to the current guidelines * Evidence of irreversible airflow obstruction on spirometry (i.e. an increase of less than 200ml and 15% in the post-bronchodilator FEV1) * 30% \< FEV1 \< 80% predicted * Stable COPD medication: no dose changes in COPD medication within last 4 weeks * Age of 40 to 75 years * Body mass index \< 30 kg/m2 * Iron deficiency: ferritin \<100 ng/mL or ferritin 100-300 ng/mL when TSAT (Transferrin saturation) \<20% * Hb between 9.5 and 13.5 g/dL * MMRC (Modified Medical Research Council Scale) 0 to 3 * Patient must be able to perform the bicycle exercise test according to investigator Exclusion Criteria: * Meeting contraindications of iv iron administration * Known active infection * C-reactive protein\>20 mg/L * clinically significant bleeding * active malignancy * History of congestive heart failure * BNP (Brain Natriuretic Peptide) ≥ 250 pg/ml * Evidence of myocardial ischemia during Cardiopulmonary Exercise Test (CPET) (i.e. chest pain or signs of ischemia in ECG) * uncontrolled Hypertension * other clinical significant chronic heart disease * Acute myocardial infarction or acute coronary syndrome, transient ischaemic attack or stroke within the last 3 months * History of peripheral artery occlusive disease * Typical claudication * Anaemia due to reasons other than iron deficiency (e.g.haemoglobinopathy) * History of erythropoietin, i.v. or oral iron therapy, and blood transfusion in previous 12 weeks and/or such therapy planned within the next 6 months * Immunosuppressive therapy or renal dialysis * ALT (Alanine Aminotransferase) or AST (Aspartate Aminotransferase) \>3times upper limit of normal * Hemochromatosis * Significant lung diseases other than COPD * pulmonary hypertension (maximum of velocity tricuspid regurgitation \> 2,8m/sec) * Exacerbation within prior 4 weeks * \> 1 exacerbation within last year * bronchoscopic lung volume reduction (BLVR) * Malignancy within the past 5 years * Autoimmune diseases * Rheumatoid diseases * Chronic renal failure (defined through: eGFR (Estimated Glomerular Filtration Rate) \< 60 ml/min) * Active diet * Physical rehabilitation training * Pregnancy, breast feeding * Participation in other therapeutic trial