Investigation whether a switch from oral iron to intravenous ferric carboxymaltose can reduce dose requirements of erythropoiesis-stimulating agents (ESA) and improve Hb levels and iron status in adult patients with non-dialysis-dependent CKD who were on a stable ESA/oral iron schedule for 6 months prior to enrolment.

Inclusion Criteria:

• >18 years of age
• Creatinine clearance ≤40 mL/min
• Hemoglobin 110-120 g/L
• Serum ferritin <100 µg/L or transferrin saturation <20%
• Monthly treatment with ESA and oral iron for at least six months before enrolment

Exclusion Criteria:

• Other obvious cause of acute or chronic anemia than iron deficiency
• Expectation to require hemodialysis within the next six months
• Short life expectancy (<1 year)
• Pregnancy
• Decompensated heart failure
• History of allergic reactions to iron preparations and/or anaphylaxis from any cause
• Requirement of blood transfusions
• Chronic decompensated mental disorder or dementia