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Iron Supplement Dosage Calculator (Ganzoni)

Calculate total iron deficit and required parenteral iron dose using the Ganzoni Formula.

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About

Treating iron deficiency anemia (IDA) often requires parenteral iron therapy when oral iron is ineffective or not tolerated. The Ganzoni formula is the clinical standard for calculating the total cumulative iron deficit. This ensures the patient receives exactly enough iron to restore Hemoglobin (Hb) to target levels and replenish body iron stores.

This calculator computes the total deficit in milligrams. It is particularly useful for planning infusion series with formulations like Iron Sucrose or Ferric Carboxymaltose. Clinical precision prevents "hemosiderosis" (iron overload) while ensuring the anemia is fully addressed. The formula accounts for the patient's weight, the differential between actual and target Hb, and a fixed value for depot iron storage.

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Formulas

The Ganzoni equation determines the Total Iron Deficit:

Irondeficit = Weight × (Hbtarget − Hbactual) × 2.4 + Irondepot

Where:

  • Weight is in kg.
  • Hb is in g/dL.
  • 2.4 is a constant (0.0034% Iron in Hb × 0.07 Blood Vol factor × 10,000 conversion).
  • Irondepot is typically 500 mg for adults (> 35 kg).

Reference Data

FormulationTrade Name (Ex)Iron Conc.Max Single Dose (typ)
Iron SucroseVenofer20 mg/mL200 - 300 mg
Ferric CarboxymaltoseFerinject50 mg/mL1000 mg
Iron DextranCosmoFer50 mg/mLTotal Dose Infusion
Ferric GluconateFerrlecit12.5 mg/mL125 mg

Frequently Asked Questions

For adults and adolescents weighing over 35 kg, the standard depot iron value is 500 mg. For smaller patients, it is often adjusted to 15 mg/kg or removed, depending on the specific pediatric guideline used.
The factor 2.4 is derived from the iron content of hemoglobin (0.34%) multiplied by the estimated total blood volume (approximately 7% of body weight or 70 mL/kg). This simplifies the calculation to a single multiplier.
No. The Ganzoni formula calculates the total bodily deficit to be replaced directly into the bloodstream. Oral iron has variable absorption rates (often <10%), so dosing is based on daily tolerability rather than a cumulative total formula.