Chronic blood transfusions are required to treat thalassaemia patients who cannot make enough RBC’s to survive. Chronic transfusion programs sustain growth, normal physiological development, and extend survival.

There are billions of RBC’s in each transfusion and each RBC contains approximately 1 billion atoms of iron. Every blood transfusion that a patient receives contains about 225 milligrams of iron. The human body has no natural mechanism to excrete iron, so numerous transfusions will cause iron to accumulate in the body and concentrate in certain areas, such as the reticuloendothelial system and in the cells of various organs, such as the heart, liver, and pancreas. If iron overload is left untreated, serious health complications start to arise as early as in the first decade of life. 

How Iron Causes Damage
Iron toxicity begins in a tissue when excess iron saturates the iron binding capacity of ferritin and transferrin.

About Ferritin and Transferrin
Ferritin is a large protein that stores iron in tissues. The liver contains most of the ferritin in the body and each ferritin protein can store about 4500 atoms of iron. Transferrin is a smaller protein that carries iron to and from locations in the body via the circulatory system. Each transferrin protein has the ability to carry 2 atoms of iron. There are large numbers of these proteins in the body, but they have a limit of capacity. In iron overload conditions, their capacity is surpassed and as a result iron is left free (unbound to a protein) to react with other molecules. Iron which is unbound to transferrin, known as non-transferrin-bound iron (NTBI), can participate in the formation of reactive oxygen species (ROS), which cause damage to cells, leading to the breakdown of tissues and eventually severe organ damage. To reduce the iron load in the body, doctors prescribe iron-chelators. Like transferrin, these drugs have the ability to bind iron, and then the complex is carried out of the system via urinary or fecal excretion. Removing the excess iron with chelators reduces the probability of organ damage occurring early in life.