Leukemia is a type of cancer that affects the body's ability to produce normal white blood cells. In Leukemia, the body makes too many abnormal white blood cells, causing-

Infections
Leukemic cells lack the infection-fighting ability of normal white blood cells.

Anemia
Production of red blood cells drops as leukemic cells flood the system.

Excessive Bleeding
Clotting ability decreases as number of platelets (tiny disk-shaped cells needed for clotting) drops.

Blood Production in a healthy human:

There are three types of blood cells that are produced in the bone marrow of a healthy human being: red blood cells (RBCs), white blood cells (WBCs) and platelets. Their ability to carry out their specified functions is instrumental to staying healthy and preventing infections.

1. red blood cells carry oxygen and carbon dioxide
2. specialized white blood cells protect the body from foreign invasions:
   1. neutrophils kills most regular bacteria. They accumulate as pus or infected wound on skin.
   2. monocytes kill bacterial infections such as tuberculosis.
   3. lymphocytes are responsible for killing viruses and the overall management of immune system. They recognize foreign materials and increase the body's resistance to infections.
3. platelet cells help clot the wound in case of bleeding. The risk of bleeding without clotting increases if the platelet count is less than 10,000-20,000.