Iron overload

This is a delayed (>24 hours), non-immunological transfusion reaction.
 

When to suspect this adverse reaction?

Patients on a chronic transfusion program (eg thalassaemia, red cell aplasia) will accumulate excess total body iron over time. Iron overload should be detected prior to any symptoms developing by ensuring chronically transfused patients have regular iron assessments (eg hepatic iron by MRI).

Early symptoms are often vague such as muscle weakness, fatigue and weight loss. Later skin pigmentation, arthropathy, diabetes, cardiac failure and hepatic dysfunction can occur.(2,3)

Evidence of iron overload requiring chelation therapy, may occur after transfusion of 10 to 20 red cell units in chronically transfused patients.(1)

Evidence of iron overload with organ dysfunction, may occur after transfusion of 50 to 100 red cell units.(2)
 

Usual causes?

Each unit of red cells contains about 250 mg of iron and the average rate of iron excretion is only about 1 mg/day.(2)

Hence in chronically transfused patients, the majority of iron can’t be excreted quickly enough and iron accumulates in the reticuloendothelial system, liver, heart, spleen and endocrine organs.(3)
 

Investigation

A long patient history of chronic red cell transfusions.(3)

Liver biopsy or iron quantification by MRI are superior than serum ferritin in determining the degree of iron overload. End organ damage can be assessed by organ specific tests.
 

What to do?

Prescribing iron chelating agents will increase iron excretion and can be used in treatment and prevention.
 

References
  1. Brittenham GM. Iron-chelating therapy for transfusional iron overload. New England Journal of Medicine 2011 Jan 13;364(2):146–156.
  2. Roback JD (ed). Non-infectious complications of blood transfusion. Chapter 27, AABB Technical Manual, 17th edition. AABB, Bethesda, 2011.
  3. Harmening DM (ed). Chapter 18, Adverse Effects of Blood Transfusion. Modern Blood Banking and Transfusion Practices, 5th edition. FA Davis Company, Philadelphia, 2005.