How should intravenous iron sucrose be administered to a pregnant woman with a hemoglobin of 8.7 g/dL who has persistent anemia despite oral iron therapy?

Administration of Intravenous Iron Sucrose in Pregnancy

For a pregnant woman with hemoglobin 8.7 g/dL and persistent anemia despite oral iron therapy, administer iron sucrose 200 mg intravenously over 10 minutes, repeated on alternate days until the calculated total iron deficit is replaced. 1

Dosing Protocol

Standard Administration Schedule

• Dose per infusion: 200 mg iron sucrose 1
• Infusion duration: 10 minutes (bolus dosing is licensed and more convenient than the older 2-hour infusion protocol) 1
• Frequency: Administer on alternate days until total calculated dose is delivered 2, 3
• Maximum single dose: Limited to 200 mg per treatment episode for iron sucrose 1

Calculating Total Iron Requirement

For a hemoglobin of 8.7 g/dL in pregnancy, the total iron deficit typically ranges from 1000-1500 mg depending on body weight 1:

• Body weight <70 kg: 1000 mg total iron 1
• Body weight ≥70 kg: 1500 mg total iron 1

This translates to 5-8 infusions of 200 mg iron sucrose given on alternate days 2, 3.

Safety Requirements

Mandatory Precautions

• Resuscitation facilities must be immediately available during all intravenous iron administrations, as anaphylaxis can occur 1
• No test dose is required for iron sucrose (unlike iron dextran, which carries higher anaphylactic risk) 1
• Monitor the patient during and for 30 minutes after each infusion 2, 3

Expected Adverse Effects

• Mild adverse events occur in approximately 8-11% of patients receiving iron sucrose 4
• Side effects are typically mild and may include metallic taste, nausea, or injection site reactions 2, 3
• No anaphylaxis has been reported with newer formulations like ferric carboxymaltose, though iron sucrose has an excellent safety profile 1

Expected Response and Monitoring

Hematologic Response Timeline

• Reticulocyte count increases significantly by day 4-7 after starting therapy 2, 5, 3
• Hemoglobin rise: Expect an increase of approximately 5.1 g/dL by day 30 with intravenous iron sucrose (compared to only 3.1 g/dL with oral iron) 2
• Serum ferritin: Should rise significantly by 4 weeks post-treatment 2, 3

Follow-Up Testing

• Recheck hemoglobin and reticulocyte count at days 7,14,21, and 30 after initiating therapy 2
• Measure serum ferritin at day 30 and at delivery 2
• Do not measure ferritin within 4 weeks of completing intravenous iron, as circulating iron interferes with the assay and produces falsely elevated results 6

Clinical Context for This Patient

Why Intravenous Iron is Indicated

With hemoglobin of 8.7 g/dL, this patient has moderate anemia (WHO definition: Hb 7-10 g/dL) and has failed oral iron therapy 1, 2. Intravenous iron is specifically indicated for:

• Intolerance to oral iron 1
• Insufficient hemoglobin increase after oral iron treatment 4
• Need for rapid hemoglobin reconstitution in pregnancy 4, 3

Advantages Over Oral Iron in This Setting

• More rapid correction: Hemoglobin rises faster with parenteral iron, though by 12 weeks the rise is similar to oral therapy 1
• Better compliance: Eliminates issues with dietary inhibitors and gastrointestinal side effects that plague oral iron 7, 3
• Effective store repletion: Serum ferritin increases significantly more with intravenous iron compared to oral therapy 2, 3

Alternative Formulation Consideration

Ferric carboxymaltose offers an alternative with potential advantages 4:

• Higher single dose: Up to 1000 mg can be given in 15 minutes (versus 200 mg for iron sucrose) 1
• Fewer infusions required: The total iron deficit can be replaced in 1-2 visits rather than 5-8 4
• Comparable safety profile to iron sucrose with similar mild adverse event rates (7.8% vs 10.7%) 4
• Greater hemoglobin rise: Mean increase of 15.4 g/L versus 11.7 g/L with iron sucrose 4

However, iron sucrose remains an excellent choice with extensive safety data in pregnancy and is more cost-effective per gram of iron (£70.80 vs £217.50) 1.

Critical Pitfall to Avoid

Never use iron dextran preparations without a test dose, as they carry a 0.6-0.7% risk of serious anaphylactic reactions and have been associated with 31 reported fatalities between 1976 and 1996 1. Iron sucrose and ferric carboxymaltose are safer alternatives that do not require test dosing 1.