Parenteral Iron Replacement For Iron Deficiency Anemia Calculator

How does this parenteral iron replacement for iron deficiency anemia calculator work?

This health tool computes the required parenteral iron replacement dose for the iron deficit extracted from the patient weight and hemoglobin level from complete blood count test.

There are three fields in the parenteral iron replacement for iron deficiency anemia calculator:

■ Weight – can be input in either lbs or kilograms and the required transformations are performed by the calculator.

■ Hemoglobin – can be input in g/dL, g/L or mmol/L and refers to the amount of hemoglobin in the red blood cells.

■ Elemental iron product – this is a choice between three iron supplement products: Iron dextran 50 mg/mL, Iron sucrose 20 mg/mL and Ferric gluconate 12.5 mg/mL.

The two formulas used are presented below:

Iron deficit in mg = Weight in kg x (14 – Hb in g/dL) x 2.145

Volume of product required in mL = Iron deficit in mg / C in mg/mL

Where C is the concentration of the iron product:

■ 50 mg/mL for Iron dextran;

■ 20 mg/mL for Iron sucrose;

■ 5 mg/mL for Ferric gluconate.

Please note that the calculations above are for information purposes only and the individual dose needs to be established by taking into account the current package insert for the elemental iron product used.

The following table present normal hemoglobin ranges:

There is another equation for iron deficit that can be used to calculate replenishment needs, that of Ganzoni, which takes into account iron stores as well and that can be found in the iron deficit calculator.

Parenteral iron and oral iron supplement

Patients diagnosed with iron deficiency are prescribed iron supplementation, either to replete body stores or to correct anemia. Oral iron therapy is the first method while IV therapy comes in place when there are contraindications or the body doesn’t respond to the oral one.

Other indications for IV are pregnancy iron deficiency, chronic renal impairment or need for rapid repletion.

The initial hemoglobin rise is more rapid with parenteral iron but on the long term (12 weeks), both therapies reach similar levels of hemoglobin.

Intravenous iron replacement can take place as total dose (as in the case of iron-dextran or iron – carboxymaltose) or as split dose (in the case of iron sucrose).

Example calculation

By taking into account the case of a patient weighing 78 kg (172 lbs) and having a hemoglobin level of 11 g/dL (110 g/L or 6.83 mmol/L). The elemental iron product used is Iron sucrose 20 mg/mL.

The result is:

■ Iron deficit = 502 mg;

■ Volume of iron product required = 25 mL.

References

1) Ganzoni AM. (1970) Intravenous iron-dextran: therapeutic and experimental possibilities. Schweiz Med Wochenschr; 100(7):301-3.

2) Koch TA, Myers J, Goodnough LT. (2015) Intravenous Iron Therapy in Patients with Iron Deficiency Anemia: Dosing Considerations. Anemia; 2015: 763576.

3) Auerbach M, Witt D, Toler W, Fierstein M, Lerner RG, Ballard H. (1988) Clinical use of the total dose intravenous infusion of iron dextran. J Lab Clin Med; 111(5):566-70.

4) Gozzard D. (2011) When is high-dose intravenous iron repletion needed? Assessing new treatment options. Drug Des Devel Ther; 5: 51–60.