Current Problems of Iron Overload

Abstract

Normally the body store of iron which is surplus to immediate requirements is regulated somewhere between 0 and 2000 mg, depending on the balance between the amounts of available dietary iron ingested and the individual’s need for iron to replace losses and to provide for growth. In order for iron stores to be increased above 2000 mg, additional iron must gain access to the body. There are two ways in which this can occur — by increased iron absorption or by parenteral iron administration. Absorption may be increased as a result of the ingestion of large amounts of iron over long periods, although it appears difficult to overcome the ability of the intestinal mucosa to regulate the quantity assimilated. At present the most convincing example of oral iron overload in the face of a normal regulatory absorptive mechanism is provided by the black populations of southern Africa, who ingest large amounts of iron in fermented alcoholic beverages [11]. Oral iron overload may also occur when the iron content of the diet is not excessive. In the metabolic disorder idiopathic haemochromatosis there is a failure of the homeostatic mechanism controlling absorption and a state of positive iron balance continues indefinitely so that there is a steady build-up in the iron content of the body [6]. A similar situation occurs in certain chronic refractory anaemias, notably thalassaemia major, and in certain patients with liver disease [16]. Parenteral iron overload is nearly always due to treatment of refractory nonhaemorrhagic anaemias with multiple blood transfusions. There are about 225 mg iron in each unit of blood, and since the body’s ability to excrete unwanted iron is limited, its iron content is increased by this amount.