A patient who is transfusion dependent may develop overload unless iron chelation therapy (ICT) is started.
Conditions with a high rate of blood transfusion include thalassemia major, sickle cell disease, aplastic anemia and myelodysplasia.
The amount of iron in blood is discussed in 03.03.03. The hematocrit of the blood product is important in determining the iron delivery per mL of blood product. Each mL of red blood cells (not blood product) delivers about 1 mg of iron. A unit of packed red blood cells delivers about 225 mg of iron.
total iron intake from blood transfusion in mg =
= (number of units transfused per month) * (years of transfusion) * (12 months in a year) *225
iron intake in g per kilogram body weight = total iron burden =
= (total iron intake in mg) / ((body weight in kilograms) * 1000)
The molecular weight of iron is 55.845 g.
iron intake in mmol per kg body weight =
= ((iron intake in g per kg) / 55.845) * 1000
Delea et al refer to a total iron burden of >= 1.05 g iron per kg body weight. Patients listed iin Table 1 of Brittenham et al had transfusional iron loads in the range of 14 to 19 mmol iron per kg body weight. 1.05 g is comparable to 18 mmol.
For a 75 kilogram adult 1.05 g iron per kg body weight is around 350 units of packed RBCs.
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Specialty: Clinical Laboratory