M ethemoglobinemia and other disorders with cyanosis
Most body iron is present in haemoglobin in circulating red cells
The macrophages of the reticuloendotelial system store iron released from haemoglobin as ferritin and haemosiderin
They release iron to plasma, where it attaches to transferrin which takes it to tissues with transferrin receptors – especially the bone marrow – where the iron is incorporated by erythroid cells into haemoglobin
There is a small loss of iron each day in urine, faeces , skin and nails and in menstrua ting females as blood (1-2 mg daily) is replaced by iron absorbed from the diet.
Stages in the development of iron deficiency
reduction in iron stores without reduced serum iron levels