Calculation of Parenteral Iron Dose (Iron Deficit)
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Equations:
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Hemoglobin iron deficit (mg) =
weight (kg) x (14 - Hgb) x (2.145) 1
Note: Hbg
(current hemoglobin level) units:
(g/dL)
Alternatively:
Volume of product required (mL) = [weight
(kg) x (14 - Hgb) x (2.145)] / C
Where C= concentration of
elemental iron (mg/ml) in the product being used:
Iron dextran: 50 mg/mL. Iron sucrose: 20 mg/mL. Ferric
gluconate: 12.5 mg/mL
Note (alternative equations):
[1 ] The Iron dextran
package insert lists the following equation:
Dose (mL) = 0.0442 (Desired Hb - Observed Hb) x LBW + (0.26 x
LBW)
Iron dextran calculator can be found
here.
[2 ] The
current package insert for
CosmoFer® lists the following equation:
Total iron deficit = Body weight [kg] x (Target Hb – Actual
Hb) [g/l] x 2.4 + Iron stores [mg]
500 mg iron for iron stores is recommended if the body weight
is above 35 kg.
A calculator using this equation can be found
here. |
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Patient Weight:
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Current Hemoglobin level:
g/dL |
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Target (desired) Hemoglobin level: g/dL |
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Background:
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Iron deficit - equation derivation1
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Assumptions:
-Blood volume = 65 mL/kg
-Hgb conc target =14.0 g/dL
-Deficits in body stores are ignored.
Intermediate calculations:
-Blood volume (dL) = [65 (mL/kg) x body weight (kg)] / 100 (mL/dL)
-Hgb deficit (g/dL) = 14.0 - patient hgb conc.
-Hgb deficit (grams) = Hgb deficit (g/dL) x blood volume (dL)
-Iron deficit (mg) = Hgb deficit (grams) x 3.3 (mg Fe/g Hgb)
[Note: 3.3 x
0.65 = 2.145]
-Volume of parenteral iron product req'd (mL) = [Iron deficit (mg)] /
C(mg/mL)
Final calculations:
-Hgb iron deficit (mg) = weight (kg) x (14 -
Hgb) x (2.145)
-Volume of product required (mL) = [weight
(kg)x (14 - Hgb) x (2.145)] / C
Where C=
concentration of elemental iron (mg/ml) in the product being used:
Iron dextran: 50 mg/mL. Iron
sucrose: 20 mg/mL. Ferric gluconate: 12.5 mg/mL
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References:
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Iron deficit equation (source):
[1 ] Schrier SL, Mentzer WC, Landaw SA. Treatment of anemia due
to iron deficiency. UpToDate®. 2010;18(3). https://www.uptodate.com/
(Requires subscription). Accessed: 4/12/2011.
Alternative equation:
Total iron deficit = Body weight [kg] x (Target Hb – Actual Hb) [g/l]
x 2.4 + Iron stores [mg]
500 mg iron for iron stores is recommended if the body weight is
above 35 kg.
[2 ] CosmoFer® package insert and product website:
https://www.cosmofer.com/product/dose-calculation/dose-calculator.aspx
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