Indications for Iron Infusion in Iron Deficiency Anemia
Intravenous iron therapy should be used when patients do not tolerate oral iron, when ferritin levels do not improve with a trial of oral iron, or when the patient has a condition in which oral iron is not likely to be absorbed. 1
Primary Indications for IV Iron
Oral iron intolerance: Patients who cannot tolerate at least two different oral iron preparations 1, 2
Inadequate response to oral iron: Despite good adherence to therapy 2
Impaired iron absorption conditions:
Severe or symptomatic anemia: When rapid correction is clinically necessary 2, 3
Ongoing blood loss: When iron losses exceed what can be replaced orally 2, 4
Heart failure with iron deficiency: To improve exercise capacity 5, 2
Specific Clinical Scenarios
Portal Hypertensive Gastropathy
- Start with oral iron supplements
- Switch to IV iron if ongoing bleeding causes inadequate response to oral therapy 1
Inflammatory Bowel Disease
- IV iron is indicated when active inflammation compromises absorption 1
- Treat underlying inflammation to enhance iron absorption 1
Chronic Kidney Disease
- IV iron is preferred, especially in hemodialysis patients 1, 2
- Consider IV iron prior to erythropoiesis-stimulating agents 1
Heart Failure
Laboratory Parameters Supporting IV Iron Use
- Ferritin not improving despite adequate oral iron trial 1
- In inflammatory states: consider IV iron when ferritin <100 μg/L with transferrin saturation <20% 2
- In non-inflammatory states: consider IV iron when ferritin <30 μg/L despite oral therapy 2
Practical Considerations
- Modern IV iron formulations that can replace iron deficits with 1-2 infusions are preferred 1, 6
- FDA-approved formulations include ferric carboxymaltose, iron sucrose, ferumoxytol, and iron dextran 5
- Dosing is typically based on hemoglobin level and body weight 2, 5
- True anaphylaxis with modern IV iron preparations is rare; most reactions are infusion-related 1, 6
- Monitor for hypophosphatemia, especially with ferric carboxymaltose 6
Monitoring After IV Iron
- Check hemoglobin response after 3-4 weeks of therapy 2
- Complete follow-up iron studies 8-10 weeks after treatment 2
- Monitor for recurrent iron deficiency every 3 months for at least a year 2
IV iron therapy has evolved significantly and now offers a safe and effective option for patients who cannot benefit from oral iron therapy. While oral iron remains first-line for most patients with iron deficiency anemia, recognizing the appropriate indications for IV iron is essential for optimal patient management.