In an adult with hemoglobin 8.4 g/dL, serum iron 27 µg/dL, total iron‑binding capacity 468 µg/dL, transferrin saturation 6 %, and ferritin 52 ng/mL, how many additional Ferrlecit (iron sucrose) infusions are needed for management?

Iron Replacement Dosing for Severe Iron Deficiency Anemia

This patient requires a total iron deficit replacement of approximately 1,000-1,500 mg elemental iron, which translates to 8-12 additional Ferrlecit (sodium ferric gluconate) infusions of 125 mg each, administered over 8-12 weeks. 1

Laboratory Analysis

Your patient presents with severe functional iron deficiency:

• Hemoglobin 8.4 g/dL – moderate anemia requiring urgent correction 2
• Transferrin saturation 6% – critically low, indicating severe iron-restricted erythropoiesis (normal >20%) 2
• TIBC 468 µg/dL – elevated, confirming true iron deficiency 1, 3
• Ferritin 52 ng/mL – appears borderline but may be falsely elevated if any inflammation present 1
• Serum iron 27 µg/dL – severely depleted 4

This constellation definitively indicates absolute iron deficiency requiring aggressive IV iron replacement, not functional iron deficiency from chronic disease. 1

Calculating Total Iron Deficit

The standard formula for total iron deficit in adults:

Total iron deficit (mg) = Body weight (kg) × (Target Hb - Actual Hb) × 2.4 + 500 mg for stores

Assuming a 70 kg adult:

• (13 - 8.4) × 2.4 × 70 + 500 = approximately 1,270 mg elemental iron needed 1

Ferrlecit Dosing Protocol

Each Ferrlecit infusion contains 125 mg elemental iron (12.5 mg/mL in 10 mL ampule). 5

Recommended Regimen:

• Dose per infusion: 125 mg (one ampule) diluted in 100 mL normal saline 5
• Infusion rate: Administer over 60-90 minutes to avoid transferrin oversaturation 5
• Frequency: Once weekly initially, then reassess 6
• Total infusions needed: 10-12 infusions (1,250-1,500 mg total) 2

Critical Safety Consideration:

Never infuse Ferrlecit rapidly (over <60 minutes) as this causes transferrin saturation >100%, creating free iron that generates toxic reactive oxygen species. Studies demonstrate that rapid infusion of 125 mg over 30 minutes produces median transferrin saturations of 207% (range 84-331%), associated with hypotension and malaise. 5 Slow infusion over 4 hours maintains saturation <100% in all patients. 5

Monitoring Schedule

Recheck iron studies 3-4 weeks after completing the initial 6-8 infusions: 2

• Target transferrin saturation: 20-50% 2
• Target ferritin: 100-500 ng/mL 2
• Expected hemoglobin rise: 1-2 g/dL over 4-6 weeks 2

Hold further iron if: 2

• Transferrin saturation ≥50% 2
• Ferritin >1,000 ng/mL 2

Treatment Algorithm

1. Weeks 1-6: Administer 125 mg Ferrlecit weekly (6 infusions = 750 mg)
2. Week 6-7: Recheck CBC, iron panel, ferritin, TIBC
3. Weeks 7-12: Continue weekly 125 mg infusions if TSAT <20% and ferritin <500 ng/mL (additional 4-6 infusions)
4. Week 12: Final reassessment – expect Hb 10-11 g/dL 2
5. Maintenance: Transition to need-based dosing (10-60 mg every 2-4 weeks) if ongoing losses 6

Important Caveats

Investigate the underlying cause of iron deficiency immediately – with this degree of depletion (TSAT 6%), assume gastrointestinal blood loss until proven otherwise. 1 Colonoscopy and upper endoscopy are mandatory even while treating. 1

Do not use oral iron in this patient – with Hb 8.4 g/dL and TSAT 6%, oral iron is inadequate and poorly tolerated. IV iron produces superior hemoglobin responses (73-93% vs 41-45% with oral iron). 2

Consider ESA therapy only if no response after completing full iron repletion – ESAs are inappropriate until iron stores are repleted (TSAT >20%, ferritin >100 ng/mL). 2

Transfusion threshold: Consider PRBC transfusion if symptomatic (severe fatigue, dyspnea, chest pain) or Hb drops below 7-8 g/dL before iron can take effect. 2