Iron Overload Due to Blood Transfusions

Mechanism and Magnitude of Effect

• Each unit of packed red blood cells delivers approximately 200-250 mg of elemental iron, leading to progressive iron overload 1, 3
• The body has no physiologic mechanism to excrete excess iron, resulting in accumulation in tissues 3, 4

Clinical Thresholds and Monitoring

• Iron overload requiring intervention is defined as serum ferritin consistently >1,000 ng/mL in the setting of chronic transfusion therapy, with a transfusion burden of ≥2 units per month sustained for more than one year 1, 2, 5, 4
• Assess serum ferritin every 3 months minimum for transfusion-dependent patients 1, 2, 5, 7

Clinical Consequences of Elevated Ferritin

• Iron overload with ferritin >1,000 ng/mL significantly worsens clinical outcomes, with a 30% increase in mortality hazard for every 500 ng/mL increase in serum ferritin above 1,000 ng/mL 3
• Higher mortality is seen with ferritin levels >1,000 ng/mL at stem cell transplantation 1, 5

Management Implications

• Iron chelation therapy should be initiated when serum ferritin reaches ≥1,000 ng/mL, or when transfusion requirement is ≥2 units per month sustained for >1 year, regardless of current ferritin level 1, 2, 5, 8, 6
• For stem cell transplant candidates, initiate chelation even with moderate iron overload, as ferritin >1,000 ng/mL at transplant increases hepatic complications and mortality 1, 5, 8, 6