In a stable adult with severe iron‑deficiency anemia (hemoglobin ~3.8 g/dL), what is the recommended intravenous iron sucrose (Fe sucrose) dose, infusion rate, frequency, and total amount to give using the Ganzoni formula, including limits per infusion and per week?

Iron Sucrose Dosing for Severe Iron-Deficiency Anemia

Immediate Dosing Recommendation

For an adult with severe iron-deficiency anemia (hemoglobin 3.8 g/dL), administer iron sucrose 200 mg intravenously over 10 minutes without dilution, repeated 2–3 times weekly until the calculated total iron deficit is met, typically requiring 10–15 doses (2000–3000 mg total) over 4–6 weeks. 1, 2

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Calculating Total Iron Requirement Using the Ganzoni Formula

The Ganzoni formula calculates total iron deficit as: Body weight (kg) × [target Hb - actual Hb (g/dL)] × 0.24 + 500 mg. 2

Practical Example for Severe Anemia (Hb 3.8 g/dL):

• For a 70 kg patient with Hb 3.8 g/dL targeting 12 g/dL (women) or 13 g/dL (men):
  • Women: 70 × (12 - 3.8) × 0.24 + 500 = 1,882 mg total
  • Men: 70 × (13 - 3.8) × 0.24 + 500 = 2,048 mg total
• Add an additional 500 mg when Hb <7.0 g/dL, bringing the total to approximately 2,400–2,550 mg. 2

Translating to Number of Iron Sucrose Doses:

• 2,400–2,550 mg total ÷ 200 mg per dose = 12–13 doses required. 1, 2

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Administration Protocol

Dose Per Infusion:

• Maximum single dose: 200 mg 3, 1
• No test dose required (unlike iron dextran formulations) 1

Infusion Rate:

• Administer 200 mg undiluted as IV push over 10 minutes 1, 4
• Alternative: 200 mg diluted in 150 mL normal saline infused over 30 minutes 5
• The 10-minute undiluted push is preferred for efficiency and is FDA-approved 3, 1

Frequency:

• Give 200 mg doses 2–3 times weekly (with at least 48 hours between doses) 1, 2
• Maximum weekly dose: 500 mg 3
• For severe anemia requiring rapid repletion, the 3-times-weekly schedule is optimal 1, 2

Total Treatment Duration:

• 12–13 doses over 4–6 weeks to deliver the calculated 2,400–2,550 mg total 1, 2

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Monitoring and Expected Response

Baseline Assessment:

• Obtain hemoglobin, ferritin, and transferrin saturation (TSAT) before starting therapy 3, 1

During Treatment:

• Recheck hemoglobin every 4 weeks until normalized 3
• Do not recheck iron studies (ferritin, TSAT) until ≥4 weeks after the final infusion, as circulating iron falsely elevates assay results 2

Expected Hemoglobin Response:

• Hemoglobin should increase by ≥2 g/dL within 4 weeks of completing the full iron sucrose course 1, 2, 6
• In severe anemia (Hb 3.8 g/dL), expect incremental rises of 0.5–1.0 g/dL per week during active treatment 6

Target Iron Parameters After Repletion:

• TSAT ≥20% and ferritin ≥100 ng/mL 1
• Maintain TSAT <50% and ferritin <800 ng/mL (preferably ≤500 ng/mL) to avoid iron overload 1

Long-Term Surveillance:

• After hemoglobin normalizes, monitor complete blood count every 3 months for the first year, then every 6 months for 2–3 years to detect recurrent anemia 3, 1

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Safety Considerations and Contraindications

Absolute Contraindications:

• Active bacteremia or uncontrolled infection—withhold iron sucrose until infection is resolved 1
• Known hypersensitivity to iron sucrose or excipients 1

Relative Contraindications:

• Acute or chronic infection may be acceptable after risk-benefit assessment if treating iron-deficiency anemia is critical 1

Adverse Event Profile:

• Hypersensitivity reactions occur in approximately 0.5% of recipients 1
• Anaphylactic reactions are extremely rare (<1:200,000 administrations) 1
• Common minor side effects: arthralgia, hypotension, injection site reactions 1
• Clinically relevant hypophosphatemia is rare with iron sucrose (≈1%), markedly lower than the 58% incidence with ferric carboxymaltose 1

Resuscitation Preparedness:

• Resuscitation facilities must be immediately available during all infusions 1, 2

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Critical Pitfalls to Avoid

Underdosing:

• The most common error is stopping after 2–3 doses when patients need 12–13 doses to fully replete iron stores in severe anemia. 2
• Always calculate total iron deficit using the Ganzoni formula before starting treatment 2

Premature Iron Studies:

• Do not recheck ferritin or TSAT until ≥4 weeks after the final dose, as immediate post-infusion levels are falsely elevated and clinically meaningless 2

Concurrent Oral Iron:

• Do not give oral iron simultaneously with IV iron therapy—it provides no additional benefit and increases gastrointestinal side effects 2

Iron Overload Risk:

• Stop further iron supplementation once TSAT reaches 50% or ferritin reaches 800 ng/mL 1

Infection Management:

• Never administer IV iron during active bacterial infection—defer until infection is controlled 1, 2

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Management of Treatment Failure

If hemoglobin fails to rise by ≥2 g/dL within 4 weeks after completing the full iron sucrose course, evaluate for:

• Ongoing blood loss (gastrointestinal, menstrual, urinary) 1
• Chronic inflammation or malignancy (elevated CRP, ESR) 1
• Bone marrow disorders (consider bone marrow biopsy) 1
• Other non-iron-deficiency causes of anemia (B12/folate deficiency, hemolysis, renal disease) 1

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Comparison with Alternative IV Iron Formulations

While iron sucrose requires multiple infusions, it offers distinct advantages in severe anemia:

Formulation	Max Single Dose	Infusion Time	Doses for 2,400 mg	Hypophosphatemia Risk
Iron sucrose	200 mg	10 min	12 doses	Low (≈1%) [1]
Ferric carboxymaltose	1,000 mg	15 min	2–3 doses	High (≈58%) [1]
Ferric derisomaltose	1,000 mg	15–30 min	2–3 doses	Moderate (≈4%) [1]

Iron sucrose is preferred when:

• The patient requires repeat infusions within a 3-month interval to minimize hypophosphatemia risk 1
• Cost considerations dominate and the healthcare setting can accommodate multiple clinic visits 1
• The patient is on hemodialysis (iron sucrose can be administered directly through the dialysis circuit) 1

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Special Considerations for Severe Anemia (Hb 3.8 g/dL)

Transfusion Decision:

• With hemoglobin 3.8 g/dL, assess for hemodynamic instability, angina, or severe symptoms requiring urgent transfusion before initiating iron therapy alone
• If the patient is stable, iron sucrose can be started immediately while monitoring closely 6

Accelerated Dosing:

• In stable severe anemia, administer 200 mg three times weekly (Monday/Wednesday/Friday schedule) to achieve more rapid repletion 1, 2

Erythropoiesis Optimization:

• Ensure adequate nutritional support (folate, B12) to support erythropoiesis during iron repletion 1
• Consider erythropoiesis-stimulating agents only if hemoglobin fails to respond after full iron repletion 1