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Iron Overload in Thalassemia Major
Transfusion therapy plays an essential role in the treatment of thalassemia (1). Untransfused children with homozygous beta-thalassemia usually exhibit one or more of the complications of defective erythropoiesis (reduced function and quality of life; increased risk of congestive heart failure, myocardial infarction, or dementia). The goal of transfusion therapy is thus to ameliorate these complications and improve survival.
Transfusion therapy extends survival in thalassemia major
Patients with thalassemia major experienced substantial increases in life expectancy when given regular, as opposed to irregular, blood transfusions (2).
Transfusion therapy extends survival in thalassemia major
Adapted with permission from Modell, Berdoukas (2).
Increased dietary iron absorption
In addition to transfusional iron overload, thalassemic patients are subject to iron overload from increased intestinal absorption of iron. Compared to normal individuals who absorb approximately 1-2 mg/day from the diet, untransfused or irregularly transfused thalassemic patients absorb approximately 3-8 mg/day (3). Ineffective erythropoiesis and peripheral red blood cell hemolysis may contribute to iron overloading (4).
Iron overload in thalassemia major
In patients with thalassemia, death due to iron overload often results from cardiac failure. Pediatric patients may develop left ventricular arrhythmias and refractory cardiac failure by their midteens (5).
Progression of untreated iron overload in thalassemia majorProgression of untreated iron overload in thalassemia major
Adapted with permission from Olivieri and Brittenham (5).
TIF recommendations for monitoring iron overload
Thalassemia International Foundation (TIF) guidelines recommend screening for iron overload at the onset of transfusions. Iron overload is likely to be detected after the first 10-20 transfusions (near age 3 years) (6). The TIF guidelines recommend monitoring of serum ferritin at least every 3 months, although they caution against reliance on serum ferritin alone without liver biopsy (6) [chapter 5]. Treatment for iron overload is recommended when serum ferritin levels reach about 1000 mcg/L, or after the first 10-20 transfusions (6).