When to Use IV Iron vs. Oral Iron Based on Iron Deficiency Severity
IV iron should be used as first-line therapy when ferritin is <30 ng/mL with transferrin saturation <20%, when hemoglobin is <10 g/dL, or in patients with active inflammatory disease. 1
Criteria for IV Iron Administration
Absolute Iron Deficiency
- Ferritin <30 ng/mL in patients without inflammation 1
- Ferritin <100 ng/mL in patients with inflammation or cancer 1
- Transferrin saturation <20% 1
Clinical Scenarios Warranting IV Iron
- Hemoglobin <10 g/dL (severe anemia) 1
- Clinically active inflammatory disease (IBD, cancer, etc.) 1
- Previous intolerance to oral iron 1
- Patients requiring erythropoiesis-stimulating agents 1
- Need for rapid correction of iron deficiency 2, 3
Criteria for Oral Iron Administration
- Mild anemia (Hb >10 g/dL) 1
- Clinically inactive disease 1
- No previous intolerance to oral iron 1
- Ferritin 30-100 ng/mL in non-inflammatory conditions 4
- Stable patients without need for rapid correction 3, 5
Special Populations Considerations
Cancer Patients
- Absolute iron deficiency: ferritin <30 ng/mL and TSAT <15% - consider IV iron 1
- Functional iron deficiency: ferritin <800 ng/mL and TSAT <20% - IV iron has superior efficacy 1
- Note: In cancer patients, inflammation may falsely elevate serum ferritin 1
Inflammatory Bowel Disease
- IV iron should be first-line for IBD patients with Hb <10 g/dL 1
- Ferritin <30 mg/L without inflammation or <100 mg/L with inflammation indicates iron deficiency 1
- IV iron demonstrates higher efficacy in achieving hemoglobin rise compared to oral iron in IBD patients 1
Chronic Kidney Disease
- Target ferritin >100 ng/mL and TSAT >20% 1
- IV iron is often necessary as oral iron usually cannot maintain adequate iron stores in hemodialysis patients 1
Comparative Efficacy
- IV iron produces faster and more robust increases in hemoglobin and ferritin levels compared to oral iron 5, 6
- In a study of severe iron deficiency anemia, IV iron increased Hb by 2.9 g/dL vs 1.6 g/dL with oral iron at 14 days 5
- IV iron demonstrates higher efficacy in achieving a hemoglobin rise of ≥2.0 g/dL compared to oral iron (OR: 1.57) 1
Safety Considerations
- IV iron administration should be performed by trained staff with resuscitation facilities immediately available 1
- Monitor patients for signs of hypersensitivity for at least 30 minutes after administration 7
- Do not administer IV iron to patients with active infection 1
- Avoid concomitant administration with cardiotoxic chemotherapy 1
- Oral iron is associated with more gastrointestinal adverse effects (metallic taste, constipation, heartburn) 1, 5
Follow-up Monitoring
- Reassess hemoglobin after 4 weeks of treatment 1
- If hemoglobin does not increase after 4 weeks of oral therapy, consider switching to IV iron 1
- After successful treatment with IV iron, re-treatment should be initiated when ferritin drops below 100 mg/L or hemoglobin falls below gender-specific thresholds (12 g/dL for women, 13 g/dL for men) 1
IV iron therapy provides superior outcomes for patients with severe iron deficiency and should be considered first-line therapy in appropriate clinical scenarios to improve morbidity, mortality, and quality of life outcomes.