What are the indications for IV (intravenous) iron therapy?

Indications for Intravenous Iron Therapy

Intravenous iron should be administered when hemoglobin is below 10 g/dL, when oral iron is not tolerated or has failed, when rapid iron repletion is required, or in the presence of active inflammation or malabsorption. 1, 2, 3

Primary Indications by Clinical Condition

Iron Deficiency Anemia (General)

• Hemoglobin <10 g/dL (100 g/L) with documented iron deficiency 1, 2
• Intolerance to oral iron (gastrointestinal side effects including nausea, flatulence, diarrhea) 1, 3
• Failure of oral iron therapy to improve iron parameters within 2 weeks of treatment 1
• Need for rapid correction of iron deficit, particularly with severe anemia-related fatigue or hemodynamic instability 1

Chronic Kidney Disease

• Non-dialysis dependent CKD with iron deficiency anemia in patients intolerant or unresponsive to oral iron 3, 4
• Hemodialysis patients requiring ongoing iron replacement due to blood losses 1, 5
• Iron deficiency defined as ferritin <100 ng/mL or ferritin 100-299 ng/mL with transferrin saturation <20% 1

Chronic Heart Failure

• Symptomatic heart failure with reduced ejection fraction (LVEF <40-45%) and iron deficiency 1, 3
• Iron deficiency criteria: ferritin <100 μg/L OR ferritin 100-299 μg/L with transferrin saturation <20% 1
• Indicated to improve exercise capacity, functional status, and quality of life 1
• May reduce cardiovascular events and heart failure-related hospitalizations 1, 4

Inflammatory Bowel Disease

• Active IBD with moderate to severe anemia (Hb <10 g/dL) 1
• Pronounced disease activity where oral iron may exacerbate inflammation through reactive oxygen species generation 1
• Ferritin up to 100 μg/L may still reflect iron deficiency in the presence of inflammation 1

Post-Surgical and Malabsorption States

• Following bariatric surgery or gastric/small bowel resection where iron absorption is impaired 1
• Autoimmune gastritis, celiac disease with ongoing malabsorption 1
• Heavy menstrual bleeding or angiodysplasia with ongoing blood losses 1

Pregnancy

• Iron deficiency anemia in pregnancy when oral iron is not tolerated or ineffective 1

Contraindications to IV Iron

• Hypersensitivity to the iron formulation or any excipients 1, 3
• Active bacteremia or ongoing serious infection (treatment should be stopped) 1
• Anemia not due to iron deficiency (other microcytic anemias) 1, 3
• Evidence of iron overload or disturbances in iron utilization 1, 3

When Oral Iron May Be Acceptable

Oral iron can be considered only when all of the following criteria are met: 2

• Anemia is mild (Hb >10 g/dL)
• No active inflammation is present
• No prior oral iron intolerance
• Patient can tolerate waiting 8-12 weeks for correction
• No malabsorption conditions exist

Safety Considerations

True anaphylaxis with modern IV iron formulations is exceedingly rare (<1:200,000 administrations). 2 Most reactions are complement activation-related pseudo-allergy (CARPA) that resolve without intervention. 2 However, there is evidence suggesting IV iron may be associated with increased infection risk, requiring careful patient selection and monitoring. 1

Cautions Requiring Specialist Input

• Patients with known drug allergies, severe asthma, eczema, or atopic conditions (increased hypersensitivity risk) 1
• Immune or inflammatory conditions (systemic lupus erythematosus, rheumatoid arthritis) 1
• Patients requiring repeat courses within 3 months should have serum phosphate levels checked due to hypophosphatemia risk 3

Monitoring After IV Iron

• Hemoglobin should increase by 1-2 g/dL within 4-8 weeks of treatment 1, 2
• Iron parameters (ferritin, transferrin saturation) should be checked 4-8 weeks after the last infusion, not within 4 weeks of a total dose infusion due to assay interference 1
• Re-evaluate iron status at 3 months after correction dose to assess need for maintenance therapy 1
• Target ferritin is 50 ng/mL in the absence of inflammation 1