The Mathematics of Iron Overload
The discussion of iron overload goes hand-in-hand with multiple blood transfusions and sickle cell disease so I thought I’d take a moment to discuss what it means to be iron overloaded and why it is so dangerous.
Our bodies absorb about 1mg of dietary iron through our intestines every day and the rest is excreted through urine, sweat and feces. Under normal circumstances, the body absorbs more iron when iron deficient and/or anemic and less when iron overloaded. Through a series of multiple steps the iron makes its way into circulation where a protein called transferrin picks it up and carries it to the bone marrow and liver where it can be used in the making of red blood cells. In most cases, the body easily maintains this delicate balance. For many individuals with sickle cell disease, however, this balance can rapidly become overwhelmed.
In SCD blood transfusions are frequently used to maintain normal hemoglobin levels and to treat many of the side effects of SCD. Transfusions are used to ameliorate the number and severity of crisis in some patients, to drastically decrease the number of strokes in children with SCD and for the treatment and prevention of acute chest syndrome. However, as with most forms of medical intervention, there is a down side…
Now for the math
There are 220 milliliters in every unit of blood (1 unit = 220 mL blood)
Transfusion of packed red blood cells adds 1mg/mL iron (1mL blood = 1mg extra iron)
If a Warrior receives 2 units of blood every 3 months then they will receive 8 units of blood per year.
(8 units) x (220 mL per unit) x (1mg iron per mL) = 1,760 mg of EXTRA elemental iron per year!
Warriors undergoing chronic transfusion therapy receive on average closer to 20 units per year.
(20 units) x (220 mL per unit) x (1mg iron per mL) = 4,400 mgm!
With so much extra iron in the body serum transferrin quickly becomes overwhelmed and cannot transport it all. The extra iron can then deposit in the liver, heart and endocrine organs causing a large amount of damage. Blood transfusions are very beneficial to many individuals with sickle cell disease, but we as Warriors, as a sickle cell community, need to be aware of the inevitable consequences of continuous blood transfusions.
So are you iron-overloaded? Talk to you doctor and make sure.