What is Polycythaemia?
This is a disease of the bone marrow, but instead of primarily affecting the white cell producing elements, it involves the areas manufacturing the red cells. Often there is an associated increase in the number of white blood cells, an increase in platelet counts and an enlarged spleen. The most likely form, called polycythaemia vera, may occur in either sex and is more probable in the second half of life. The cause is unknown.
As the blood becomes packed with red cells, its general fluid nature (so-called viscosity) is impaired. This can affect the flow through the brain, causing headaches, nausea, inability to concentrate clearly, visual disturbances, some difficulty in swallowing, and maybe hemiplegia (wherein one half of the body becomes paralysed). There is a greatly increased risk of blood clots occurring in the cerebral vessels, in the arteries of the heart and in the lower limbs.
Haemorrhaging may occur, particularly in the intestinal system, due to anomalies with the platelets. The patient often has a ruddy appearance, sometimes with a bluish tinge of the extremities, and occasionally visits the doctor complaining of gout. The level of uric acid in the blood is often raised, and the joints may become extremely painful. There may be generalised itching, and the spleen may be enlarged. Various tests will confirm the diagnosis, and there is a typical blood picture when examined by the pathologists under the microscope. Examination of samples taken from the bone marrow also shows characteristic alterations from normal samples.
As there is a high risk of clotting in the vessels and the chance of sudden death, treatment is imperative. Therapy must be carefully carried out, usually in a major hospital where the full range of facilities is available and specialised care is obtainable. The nature of therapy has varied a good deal recently, and is still undergoing alterations. Use of the substance 32 P or chemotherapy (usually in the form of busulphan) may be undertaken, and removal of blood by venesection. The former controls the excessive levels of platelets, and the latter helps control the enormous increase in the red-cell counts.
Treatment has improved the outlook for these patients considerably. Before treatment became available, at least half of the patients died within 18 months of diagnosis. When venesection was introduced to remove the excess red cells, this period of survival was extended to around three and a half years. After the introduction of radioactive phosphorus and chemotherapy, this has lengthened to around 12 years. Newer forms of drug therapy are constantly being devised.