What are the indications and contraindications for iron infusion in patients with iron deficiency anemia?

Indications and Contraindications for Iron Infusion

Intravenous iron therapy should be used when patients cannot tolerate oral iron, when ferritin levels do not improve with oral iron trial, or when patients have conditions in which oral iron is not likely to be absorbed. 1

Indications for Iron Infusion

Primary Indications

• Intolerance to oral iron therapy (gastrointestinal side effects) 1
• Failure to respond to oral iron therapy (no hemoglobin increase of at least 10 g/L after 2 weeks) 1
• Conditions with impaired iron absorption:
  • Active inflammatory bowel disease 1, 2
  • Post-bariatric surgery 1
  • Ongoing inflammation with compromised absorption 1

Specific Clinical Scenarios

• Portal hypertensive gastropathy with ongoing bleeding not responding to oral iron 1
• Chronic kidney disease with iron deficiency anemia 3
• Need for rapid correction of iron deficiency (e.g., preoperative patients) 1
• Severe iron deficiency anemia (Hb < 10 g/dL) with active IBD 2
• Transfusion-dependent iron deficiency anemia 1

Contraindications for Iron Infusion

Absolute Contraindications

• Known hypersensitivity to the specific iron formulation 3
• Iron overload or hemochromatosis 3

Relative Contraindications/Cautions

• First trimester of pregnancy (safety not established)
• Active infection (may worsen with iron supplementation)
• Liver disease with elevated transaminases
• History of multiple drug allergies (increased risk of hypersensitivity)

Choosing Between Oral and IV Iron

When to Use Oral Iron First

1. Mild to moderate iron deficiency anemia
2. No contraindications to oral therapy
3. No urgent need for rapid correction
4. No malabsorption conditions

When to Choose IV Iron First

1. Severe symptomatic anemia requiring rapid correction
2. Known malabsorption disorders
3. Active inflammatory bowel disease 1, 2
4. Post-bariatric surgery patients 1
5. Chronic kidney disease patients 3

Monitoring and Safety Considerations

Before IV Iron Administration

• Confirm iron deficiency diagnosis (ferritin < 30 μg/L or 30-100 μg/L with transferrin saturation < 20%) 2
• Check for history of hypersensitivity reactions
• Ensure resuscitation facilities are available 1

During Administration

• Monitor for signs of hypersensitivity reactions for at least 30 minutes 3
• Watch for hypotension during and after administration 3
• For mild reactions, stop infusion and restart at slower rate after 15 minutes 1

After Administration

• Expect hemoglobin increase of at least 1 g/dL within 2 weeks 1, 2
• Monitor hemoglobin, ferritin, and transferrin saturation
• Continue monitoring at 3-month intervals for at least 1 year 1

Practical Considerations

Preferred IV Iron Formulations

• Formulations that can replace iron deficits with 1-2 infusions are preferred 1
• Options include:
  • Ferric carboxymaltose (750-1000 mg per dose)
  • Ferric derisomaltose (1000 mg per dose)
  • Iron sucrose (multiple doses of 100-200 mg)
  • Iron dextran (total dose infusion possible but higher risk of reactions) 1

Common Pitfalls to Avoid

1. Failing to identify and treat the underlying cause of iron deficiency
2. Mistaking infusion reactions for true anaphylaxis (most are complement activation-related pseudo-allergy) 1
3. Using diphenhydramine for reactions (can mask worsening symptoms) 1
4. Overlooking hypophosphatemia as a potential side effect of ferric carboxymaltose 4
5. Not continuing treatment long enough to replenish iron stores

IV iron therapy is generally safe with serious adverse events being rare. The risk of moderate to severe infusion reactions affects less than 1% of patients across all modern preparations 4. When administered properly with appropriate monitoring, IV iron can effectively correct iron deficiency anemia with minimal risk to patients.