Form of anaemia that arises because of iron deficiency, iron being one of the key constituents of red blood corpuscu-les. Iron deficiency does not usually result from a lack of iron in the food, because more than enough iron is present in a normal diet. This form of anaemia usually arises as a result of frequent loss of blood. Possible causes are severe menstrual bleeding or haemorrhaging in the gastro-intestinal tract. These can continue for a long time before being noticed. In pregnant women, the growing embryo also absorbs a lot of iron. Since pregnancy and menstruation are major causes of iron-deficiency anaemia, the condition is commoner in women than in men. In anaemia caused by iron deficiency, difficulties in swallowing, a smooth tongue and stomach disorders can occur in addition to the general symptoms of anaemia, which are paleness, tiredness, heart palpitations and dizziness. Small cracks in the skin at the corners of the mouth are also seen in anaemia caused by iron deficiency.