Ferric Carboxymaltose With or Without Phosphate Substitution for the Treatment of Iron Deficiency or Iron Deficiency Anemia

Inclusion Criteria: * Informed Consent as documented by signature (Appendix 5: Informed Consent Form) * Male or female ASA 1 to 3 patients, at least 18 years old * Scheduled for an elective major abdominal or thoracic surgery. * Patients with isolated iron deficiency (defined as hemoglobin concentration (Hb) \> 130 g/l, and plasma Ferritin \< 100 ng/ml or TSAT \< 20%), or iron deficiency anemia (defined as Hb 100-130 g/l, and plasma Ferritin \< 100 ng/ml or TSAT \< 20%). * Patients scheduled to be hospitalized ≥ 3 days. Exclusion Criteria: * Patients with known anaphylactic reactions to parenteral iron products. Patients with allergy/hypersensitivity to any contents of Ferinject® or Phoscap®. * Patients with iron overload or disturbances in utilization of iron (e.g. haemochromatosis, hemosiderosis). * Patients with ≥3 times increase in aspartate aminotransferase or alanine aminotransferase as per reference range. * Patients with excessive blood loss requiring massive transfusion (≥ 10 more red blood cell units). * Patients with known myelodysplastic syndromes. * Patients with chronic kidney disease with an estimated GFR \< 30 ml/min or with end-stage renal disease requiring scheduled dialysis. * Patients with known urinary tract infections with urea-splitting bacteria. * Patients with known diseases influencing phosphate, calcium or vitamin D homeostasis (e.g. Hyperparathyroidism, X-linked hypophosphatemia, renal tubular acidosis). * Patients taking medication significantl…