Parenteral Iron Replacement For Anemia Calculator

Variables and formula

This parenteral iron calculator uses the patient weight and haemoglobin level to compute the iron deficit.

Hb levels are extracted from the complete blood count test.

There is flexibility in terms of the measurement unit for the variables used: weight can be input in either kg or lbs whilst haemoglobin can be input in g/dL, g/L or mmol/L.

There is also a third variable which requests for the type of elemental iron product intended for replenishment of iron stores. The choice is between Iron dextran 50 mg/mL, Iron sucrose 20 mg/mL and Ferric gluconate 12.5 mg/mL.

The formula used for iron deficit is:

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

The volume of product in mL can be calculated by diving the iron deficit to the mg/mL value of the product used, which is:

■ 50 mg/mL for Iron dextran;

■ 20 mg/mL for Iron sucrose;

■ 5 mg/mL for Ferric gluconate.

It is important to note that the above calculations merely provide estimates and that individual dosage should be established by a medical professional based on the current package insert for the elemental iron product used.

The following table introduces the normal haemoglobin ranges for three categories of patients and in three measurement units:

The iron deficiency calculator uses a similar calculation method (the Ganzoni formula) for replenishments needs but also accounts for existent iron stores.

Parenteral and oral iron supplement

When a patient is discovered with iron deficiency during control tests, iron supplementation therapy is prescribed to balance depleted body stores or correct any possible anemia.

Oral iron therapy is the first preferred method whilst IV therapy usually comes in when there are contraindications or the body doesn’t respond to oral iron.

In some cases of pregnancy iron deficiency, renal impairment or after acute haemorrhage, IV iron is recommended because the initial haemoglobin rise is more rapid. However, on the long term (3 months), both oral and parenteral iron have similar effects on haemoglobin.

Therapy with iron-dextran or iron-carboxymaltose is total dose whilst with iron sucrose is split dose.

References

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

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

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