Agents used in anaemias

Nomiul erj lhnipoiesis requires iron, viiumin nnil folic acid. A deficiency of any of these causes anaemia. Erythropoietic activity is regulated by erythix oietiii. a hormone released mainly by the kidneys. In chronic renal failure, anaemia often occurs because of a I all in erythropoietin production. 

Iron is necessary for haemoglobin production, and iron deficiency results in small red blood cells with insufficient haemoglobin (microcytic hypochromic anaemia , The administration of iron preparations (top right) is needed in iron deficiency, which may be because of chronic blood loss (e.g. menorrhagia), pregnancy (the fetus takes iron from the tnoiher), various abnormalitic-s of the gut (imn absorption may be reduced) or premature birth (such babies tire bom with very low iron. stores). 

Vitamin B,j and folic acid arc e.ssential for several reaclion.s necessary for normal DN.A synthesis. A deficiency of either vitamin cau.ses impaired production and abnomial maturation of crythroid precursor 

Vitamin deficiency occurs when there is malabsorption because of a lack of intrinsic factor (pernicious anttemia). following gastrectomy (no intrinsic factor), or in various small bowel diseases, where absorption is impaired. Because the disease is nearly always cau.sed by malabsorption. oral vitamin administration is of little value, and replacement Iherapy, usually for life, involves injections of vitamin (left). Hydroxocobulamin is the form of choice for ilierapy because it is retained in Ihe body longer than cyanocobalamin (cyanocobalamin is bound less to plasma proteins and Ls more rapidly excreted in urine). 

Folic acid deficiency leading to a megaloblastic anaemia, which requires oral folic acid (bottom right), may occur in pregnancy (folate requirement is increased) and in malabsorption syndromes (e.g. sieai-orriioea and sprue). 

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