Leukemia describes a number of disorders of blood-forming tissues, in which the white BLOOD cells steadily increase. The white blood cells crowd out the red blood cells and platelets so that the person cannot get enough oxygen and bleeds easily. The cause of leukemia is unknown, although there is a possibility that an obscure VIRUS is involved.
   In leukemia these new cells become increasingly numerous and are found in all body tissues. This abnormal production of cells changes the content of the blood. In some patients the disease progresses slowly; this is chronic leukemia. In other patients the cells are poorly formed and more quickly produced; this is acute leukemia. Chronic leukemia usually occurs between twenty and forty years of age. Acute leukemia occurs more frequently in people under twenty-five years of age.
   The victims have loss of appetite, loss of weight, a slight temperature, bone pain and mild ANEMIA. They are weak, pale and usually tire easily. The SPLEEN and often the LIVER are enlarged.
   The physician depends on laboratory findings for diagnosis. Samples of BONE marrow and blood are examined. In leukemia these samples contain an abnormal number of white cells and a reduced number of red cells and platelets that are immature and imperfectly formed.