Iron Overload and FerriScan

Iron Overload - Hereditary and Transfusional

Disorders of iron metabolism are amongst the most common diseases in the world. Hereditary Hemochromatosis is a condition where excessive uptake of dietary iron leads to accumulation of iron and affects around 1 in 227 people of Northern European decent.

Additionally, iron accumulates due to repeated blood transfusions in patients with blood disorders such as ß-thalassemia, sickle cell anaemia and myelodysplastic syndrome (MDS). One unit of transfused red cells delivers approximately 250mg of iron to the body. Since the human body has no natural mechanism for excreting excess iron, repeated transfusion will lead to iron overload. Iron chelation therapy is required to prevent iron-related tissue damage.

Controlling total body iron stores (TBIS)

Free or labile iron causes tissue damage. Deposit of excess iron in tissues are a source of free iron. Initially, the liver and spleen are the primary site of excess iron deposition. If total body iron stores are allowed to exceed the body's total iron binding capacity, precipatation of iron in other tissues such as the heart follows (see e.g Jensen et al Blood 2003: 101, 4632-4639). The goals of chelation therapy are to prevent free iron circulating in the body and to prevent total body iron stores exceeding the total iron binding capacity.

Why is liver iron concentration (LIC) measurement important?

Liver iron concentration is the most effective measurement of total body iron stores (See Figure 1). Measurement if LIC provides clinicians with the accurate information they need to determine when to initiate or adjust chelation therapy.

Effective control of total body iron stores has been shown to significantly reduce the risk of cardiac disease and death in patients with thalassaemia major (See Figure 2).

The Thalassemia International Federation (TIF) guidelines for the Clinical Management of Thalassemia (November 2008) states that "liver iron concentration is now regarded as the reference standard for estimating body iron loading and has been shown accurately to predict total body iron stores."

Figure 1 : Relationship between hepatic iron and total body iron stores

Total body iron stores measured by quantitative phlebotomy of post bone marrow transplant thalassaemia major patients showed a strong correlation with LIC measured by liver biopsy (Angelucci et al, N Eng J Med 2000; 343: 324-331).