ABSTRACT
Abnormalities of clotting factors can give rise to severe bleeding disorders, of which the best known is haemophilia resulting from deficiency of factor eight. Haemophilia and the related syndromes are inherited disorders. The platelets within the peripheral blood have an important function in sealing blood vessels, and a deficiency in their numbers will give rise to a bleeding
tendency. This is associated with the occurrence of purpura (areas of bleeding into the skin and mucous membranes) if the platelet count is sufficiently low. Typical causes of a low platelet count include acute leukaemia, aplastic anaemia (in which there is failure of the bone marrow) and a number of other specific disorders. In one particular syndrome-von Willebrand’s diseasethere is a mixture of a deficiency of factor eight with a prolonged bleeding time, thought to be due to an associated abnormality of the blood vessels.
