Calculation of Parenteral Iron Dose (Iron Deficit)

Equations:

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 ] An earlier version of the
Venofer® package insert as well as 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.

Iron deficit - equation derivation^{1}
: 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

Source:
Venofer® (Iron Sucrose Injection, USP) package insert -
(2006).
NOTE: Latest package insert does not
include this information.

Calculation of dosage:
The total cumulative dose of Venofer, equivalent to the
total iron deficit (mg), is determined by the haemoglobin
level and body weight. The dose of Venofer must be
individually determined for each patient according to the
total iron deficit calculated with the following formula:

Total iron deficit [mg]
= body weight [kg] x (target Hb-actual Hb) [g/dl] x 2.4*
+ depot iron [mg]

Below 35 kg body
weight:

Target Hb = 13 g/dl and depot iron = 15 mg/kg
body weight

35 kg body weight
and above:

Target Hb = 15 g/dl and depot iron = 500 mg

*
Factor 2.4 = 0.0034 x 0.07 x 10000:

Iron content of
hemoglobin

~ 0.34%

Blood volume

~ 7% of body
weight

Conversion from
g/dl to mg/l

= Factor 10000

Depot iron refers to the approximately 20% of
the total iron content in the body stored in
ferritin and hemosiderin in cells of the
recticuloendothelial system (liver, spleen, and
bone marrow).

Total amount of
Venofer to be administered (in ml)

=

Total iron deficit
[mg]

20mg/ml

References:

Iron deficit equation (source):
[1 ] Schrier SL, Mentzer WC, Landaw SA. Treatment of anemia due
to iron deficiency. UpToDate®. 2010;18(3). http://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:
http://www.cosmofer.com/product/dose-calculation/dose-calculator.aspx

Disclaimer

All calculations must be confirmed before use. The authors make no claims of the accuracy of the information contained herein; and these suggested doses are not a substitute for clinical
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