Calculation of parenteral iron dose for treatment of adults with iron deficiency anemia

Required information

Body weight (kilograms) = BW

If patient is obese, use lean or ideal body weight*

Hemoglobin concentration (g/dL) = Hgb

Concentration of elemental iron in the parenteral product (mg/mL) = C^¶

Assumptions

Blood volume is 65 mL per kilogram

Hemoglobin concentration to be corrected to 14 g/dL

Each gram of hemoglobin contains 3.3 mg of iron

Addition of iron for repletion of body stores is optional

Intermediate calculations

Blood volume (dL) = 65 (mL/kg) x body weight (kg) ÷ 100 (mL/dL)

Hemoglobin deficit (g/dL) = 14 - patient hemoglobin concentration

Hemoglobin deficit (g) = hemoglobin deficit (g/dL) x blood volume (dL)

Iron deficit (mg) = hemoglobin deficit (g) x 3.3 (mg Fe/g Hgb)

Volume of parenteral iron product required (mL) = iron deficit (mg) ÷ C (mg/mL)

Final calculations^Δ

Hemoglobin iron deficit (mg) = BW x (14 - Hgb) x (2.145) + iron to replenish stores if desired (mg)

Volume of product required (mL) = BW x (14 - Hgb) x (2.145) ÷ C (if no added iron for stores)

Example

60 kg woman with a hemoglobin concentration of 8 g/dL. Parenteral iron product is iron sucrose (C = 20 mg elemental iron/mL). No additional iron to replenish stores.

Hemoglobin iron deficit = 60 x (14 - 8) x (2.145) = 772 mg iron

Volume of iron sucrose needed = 60 x (14 - 8) x (2.145) ÷ 20 = 38.6 mL^◊

* Calculators are available in UpToDate to determine ideal body weight and lean body weight.
¶ The concentration of elemental iron in the various products is, as follows: iron dextran: 50 mg/mL; iron sucrose: 20 mg/mL; ferric gluconate: 12.5 mg/mL; ferumoxytol: 30 mg/mL; ferric carboxymaltose: 50 mg/mL.
Δ These calculations are based upon the assumptions listed above. If correction is desired for a different blood volume, final hemoglobin concentration, or for additional iron for body stores, the intermediate calculations can be employed.
◊ The product information sheet should be consulted in order to determine the need for a test dose, proper dilution of the product and rate of infusion, as well as the maximal suggested dose per infusion session.

Graphic 54677 Version 7.0

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Calculation of parenteral iron dose for treatment of adults with iron deficiency anemia