When the level of haemoglobin - the vita protein molecule which carries oxygen in the bloodstream - is lowered, or the number of red blood cells falls below normal levels, the supply of oxygen to the tissues is reduced.
The anaemia which results may be mild manifesting itself as tiredness and general weakness. Or severe, when symptoms of lethargy are more marked and accompanied by paleness, heart palpitations, breathlessness, giddiness, swollen feet and leg pains.