When a person receives a blood transfusion, they are receiving not only red blood cells but also the iron contained within those cells. Each unit of transfused red blood cells contains about 200-250 mg of iron. The body will break down the transfused red blood cells over time, and the iron from these cells will be released and made available for the body to use or store.
Individuals who often get blood transfusions, like those with chronic diseases or chronic anemia, can end up with too much iron in their bodies. This is termed transfusional iron overload. This overload is concerning because our body can't easily get rid of excess iron. Over time, this iron can accumulate in organs like the heart, liver, and certain glands, which can lead to organ damage.To manage and keep an eye on iron levels in those who get regular transfusions, doctors might:
Check serum ferritin levels: This protein stores iron, and its level can hint at the body's total iron stores. A high ferritin level can mean there's too much iron in the body.
Use iron chelation therapy: This is a treatment where medications are used to bind and remove excess iron from the body. Common medicines for this include deferoxamine, deferasirox, and deferiprone.
Monitor organs: As excess iron can damage organs, it's crucial to keep a regular check on their function. This might include testing liver function or heart evaluations.
Advise on diet: Sometimes, patients might be told to eat less iron-rich food. However, the iron we get from food usually isn't as concerning as the iron from transfusions.
- Phlebotomy: In certain situations, doctors might remove some blood to decrease iron levels. This method is more common for conditions like hereditary hemochromatosis, where the body absorbs too much iron from food.
For certain patients, especially those with sickle cell disease, a specific procedure called Red Blood Cell (RBC) exchange, or erythrocytapheresis, is sometimes recommended. This procedure is different from a simple blood transfusion and can be beneficial in managing iron overload.
Red Blood Cell Exchange for Sickle Cell Patients:
In RBC exchange, the patient's blood is drawn out and passed through a machine that separates the components of the blood. The sickled red blood cells (which are misshapen and can cause blockages in the blood vessels) are removed and replaced with healthy donor red blood cells. The plasma, white blood cells, and platelets are typically returned to the patient. This means that the patient receives fresh red blood cells without a significant increase in blood volume or iron.
Why RBC Exchange Helps with Iron Overload:
Limited Iron Intake: In a standard transfusion, the patient receives additional blood, which brings with it the iron contained in the red blood cells. Over time and with frequent transfusions, this can lead to iron overload. In contrast, with RBC exchange, because the patient's own sickled blood is being removed and replaced, there is no significant net gain in iron.
Chronic Transfusion Alternative: Some sickle cell patients might be on a chronic transfusion regimen to prevent complications like strokes. These regular transfusions can rapidly lead to iron overload. RBC exchange offers a way to get the benefits of the transfusion (like increasing the percentage of healthy red blood cells) without the added risk of iron buildup.
Better Symptom Management: Apart from the iron overload aspect, RBC exchange can also help manage sickle cell crisis symptoms by rapidly decreasing the percentage of sickled cells in circulation.
More About Iron
Iron Homeostasis in the Body: The human body has a sophisticated system for regulating iron levels. The body absorbs iron from food in the intestines and uses it to make hemoglobin in red blood cells. When red blood cells die (typically after about 120 days in circulation), the body recycles the iron. Importantly, humans don't have a direct mechanism to excrete large amounts of iron. So, introducing additional iron via transfusions can disrupt this equilibrium, leading to increased iron stores.Why Iron Overload is Harmful: We touched upon the organ damage caused by iron overload, but it's worth emphasizing that free iron (not bound to proteins) can catalyze the formation of free radicals, which can damage cells, proteins, and DNA. This oxidative stress is what leads to organ damage in conditions like hemochromatosis and transfusional iron overload.
Alternatives to Blood Transfusion: For patients at risk of iron overload, doctors might explore alternatives to blood transfusions when possible. For example:
Erythropoiesis-stimulating agents (ESAs): These are drugs that stimulate the bone marrow to produce more of its own red blood cells, reducing the need for transfusions.
Iron-modifying agents: There are some agents that can bind to free iron in the bloodstream, potentially reducing the risk of iron-related complications.
Optimized surgical and treatment techniques: In surgeries or treatments that might require transfusions, optimizing techniques to minimize blood loss can reduce the need for transfusions.
Individual Variation: Not everyone responds to transfusions in the same way. Some people may absorb and store iron from transfusions more efficiently than others. Factors such as genetics, underlying health conditions, and age can all influence how a person's body handles extra iron.
Iron and Infections: Elevated iron levels and hemochromotosis can increase
susceptibility to certain infections, as many pathogens thrive in
iron-rich environments. This is another reason why managing iron levels
is crucial, especially in patients receiving regular transfusions.