In iron deficiency the amount of iron needed is important in planning a patient's treatment.
Method in Williams (1990)
milligrams of iron required for treatment =
= (iron needed to correct anemia) + (iron needed to replenish iron stores)
milligrams of iron needed to correct anemia =
= ((normal hemoglobin) - (current hemoglobin)) * (body weight in pounds) =
= ((normal hemoglobin) - (current hemoglobin)) * (body weight in kilograms) * 2.2
where:
• The normal hemoglobin is 16 g/dL.
• body weight in pounds = (body weight in kilograms) * 2.2
milligrams of iron needed to replenish iron stores
• 1000 mg in adult males
• 600 mg in adult females
Iron dextran has 50 mg iron per mL and is the only preparation approved for parenteral therapy.
mL of iron dextran required =
= (mg of iron required) / 50
Derivation:
(1) 1 mg of RBCs contains 1 mg of iron.
(2) total blood volume is approximately 65 mL/kg
(3) iron content of hemoglobin is 0.34% by weight = 0.0034 g iron per g hemoglobin
(4) (1 deciliter) / 100 = 1 mL
iron required in grams =
= ((whole blood hemoglobin deficit in g/dL) / 100) * (body weight in kg) * (65 mL / kg) * (0.0034)
Method of Auerbach et al
milligrams of iron required to correct deficit and to replenish marrow stores =
= 0.3 * (body weight in pounds) * (100 - (((hemoglobin in g/dL) * 100) / 14.8))
