Chapter 2: Use of iron to treat anemia in CKD

BACKGROUND Correction of iron deficiency with oral or intravenous iron supplementation can reduce the severity of anemia in patients with CKD. Untreated iron deficiency is an important cause of hyporesponsiveness to ESA treatment. It is important to diagnose iron deficiency because treatment can readily correct the associated anemia and investigation for the cause of iron deficiency, which should follow its detection, can lead to important diagnoses. In the absence of menstrual bleeding, iron depletion and iron deficiency usually result from blood loss from the gastrointestinal tract. There are additional considerations in CKD patients with iron deficiency. For instance, hemodialysis patients are subject to repeated blood loss due to retention of blood in the dialyzer and blood lines. Other contributing causes in hemodialysis and other CKD patients include frequent blood sampling for laboratory testing, blood loss from surgical procedures (such as creation of vascular access), interference with iron absorption due to medications such as gastric acid inhibitors and phosphate binders, and reduced iron absorption due to inflammation. The reader is referred to standard textbooks of medicine and pediatrics for more extensive discussions on the diagnosis and evaluation of patients with known or suspected iron deficiency. Iron supplementation is widely used in CKD patients to treat iron deficiency, prevent its development in ESAtreated patients, raise Hb levels in the presence or absence of ESA treatment, and reduce ESA doses in patients receiving ESA treatment. Iron administration is appropriate when bone marrow iron stores are depleted or in patients who are likely to have a clinically meaningful erythropoietic response. It is prudent, however to avoid iron therapy in patients in whom it is unlikely to provide meaningful clinical benefit, i.e., avoid transfusion and reduce anemia-related symptoms, and in those in whom potential benefit is outweighed by risks of treatment. There are relatively few data on the long-term clinical benefits of iron supplementation other than direct effects on the Hb concentration. There is similarly little information on the long-term adverse consequences of iron supplementation in excess of that necessary to provide adequate bone marrow iron stores. Since bone marrow aspiration for assessment of iron stores is rarely done in clinical practice, iron supplementation is typically assessed by blood-based iron status tests without knowledge of bone marrow iron stores. The following statements provide recommendations for use of iron supplementation in patients with CKD.