What is the recommended IV (intravenous) iron dosing regimen for patients with iron deficiency anemia?

Intravenous Iron Dosing for Iron Deficiency Anemia

For patients with iron deficiency anemia requiring IV iron, the recommended dosing is 750 mg intravenously in two doses separated by at least 7 days for a total cumulative dose of 1,500 mg of iron per course for patients weighing 50 kg or more. 1

Patient Selection for IV Iron Therapy

IV iron is indicated when:

• Oral iron therapy has failed or is not tolerated
• Rapid iron repletion is needed due to severe anemia (Hb <10 g/dL)
• Patient has conditions affecting iron absorption:
  • Active inflammatory bowel disease
  • Postgastrectomy
  • Gastric bypass surgery
  • GI tract disorders aggravated by oral iron 2, 3

Dosing Regimens by Preparation

Ferric Carboxymaltose (Injectafer)

• For patients ≥50 kg: 750 mg IV in two doses separated by at least 7 days (total 1,500 mg) 1
• For patients <50 kg: 15 mg/kg body weight IV in two doses separated by at least 7 days 1
• Administration time: 15 minutes 2
• Can be given undiluted as slow IV push or diluted in 250 mL normal saline 1

Ferric Derisomaltose

• Maximum single dose: 20 mg/kg (up to 1,500 mg) 2
• Administration time: 15-30+ minutes 2

Iron Sucrose (Venofer)

• Typical dose: 200 mg per administration 2
• For hemodialysis patients: 100 mg per dose 2, 4

Calculating Total Iron Deficit

Research shows that the average iron deficit in patients with iron deficiency anemia is approximately 1,400-1,500 mg 5, supporting the standard 1,500 mg total dose for most adult patients.

Two approaches to calculate iron deficit:

1. Simplified Dosing Scheme (preferred):

   • Based on hemoglobin level and body weight 3
   • For most adults: 1,500 mg total dose 5

2. Ganzoni Formula (more complex):

   • Total iron deficit (mg) = body weight (kg) × [target Hb - actual Hb (g/dL)] × 0.24 + 500 3
   • Less commonly used in practice due to complexity 3

Monitoring and Follow-up

• Measure hemoglobin response 2-4 weeks after treatment 3
• Target increase: at least 2 g/dL within 4 weeks 3
• Monitor serum phosphate levels, especially with ferric carboxymaltose, due to risk of hypophosphatemia 2, 6
• Check iron parameters (ferritin, transferrin saturation) 8-10 weeks after infusion 3
• Target parameters:
  • Hemoglobin: 10-12 g/dL
  • Ferritin: >100 ng/mL
  • Transferrin saturation: >20% 2

Special Considerations

Safety Precautions

• Monitor for hypersensitivity reactions during and after administration 2
• Anaphylaxis is rare (<1:200,000 administrations) 3
• Most common reaction is complement-activated related pseudo-allergy (CARPA) 3
• Avoid extravasation as it can cause long-lasting brown discoloration 1

Retreatment Considerations

• Lower retreatment rates with 1,500 mg total dose (5.6%) compared to 1,000 mg (11.1%) 5
• Check serum phosphate levels before repeat courses, especially if within 3 months 1
• Treat hypophosphatemia as medically indicated 1

Special Populations

• For patients with heart failure and iron deficiency:
  • Weight <70 kg with Hb <10 g/dL: 1,000 mg on day 1,500 mg at week 6
  • Weight ≥70 kg with Hb <10 g/dL: 1,000 mg on day 1,000 mg at week 6 1

IV iron therapy has evolved significantly with newer formulations allowing for higher single doses with excellent safety profiles, making it possible to correct iron deficiency with fewer infusions while improving patient outcomes.