Iron Content in One Unit of Red Blood Cells
One unit of red blood cells (RBCs) contains approximately 200-250 mg of iron. 1
Iron Content in Blood Products
The iron content in blood products is well-established in medical literature:
- A standard unit of RBCs contains 200-250 mg of elemental iron 1
- This iron is primarily bound to hemoglobin within the red blood cells
- Pure RBC concentrates contain approximately 1.16 mg/mL of iron, while whole blood contains about 0.47 mg/mL 1
Clinical Significance of Transfusional Iron
Iron Accumulation
- Each transfused unit contributes significantly to the body's iron stores
- For pediatric patients, a transfusion of 15 mL/kg provides approximately 8-12 mg/kg of iron 1
- Iron overload can occur after receiving 20-25 units of RBCs 1
Metabolism of Transfused Iron
- The lifespan of transfused erythrocytes is typically 60-70 days 1
- Most iron from transfused cells is not accessible for neonatal use until the RBCs are broken down 1
- After RBC breakdown, the iron is either recycled for new RBC production or stored as ferritin
Iron Overload Considerations
- Transfusion-dependent patients invariably develop secondary iron overload 1
- Iron overload can lead to organ dysfunction, particularly affecting the liver, heart, and endocrine organs 1
- In patients receiving chronic transfusions, iron chelation therapy should be considered when serum ferritin exceeds 1000 ng/mL 1
Practical Applications
Transfusion Strategies
- When transfusing, consider that each unit will increase hemoglobin by approximately 1 g/dL in average-sized adults 2
- Body mass index affects the expected rise in hemoglobin, with smaller patients experiencing a larger increase 2, 3
- Transfuse one unit at a time in non-hemorrhaging patients and reassess after each unit 2
Iron Management
- For patients requiring multiple transfusions, monitoring iron status is essential
- Iron chelation should be considered in transfusion-dependent patients with serum ferritin >1000 ng/mL after approximately 25 units 1
- In neonates, consider withholding iron supplementation for a period following blood transfusion to minimize iron overload risks 1
Understanding the iron content of blood products is crucial for managing patients requiring transfusions, particularly those needing chronic transfusion support, to prevent complications from iron overload while ensuring adequate hemoglobin levels.