Blood is the red fluid that goes to all parts of the body through the veins and arteries. Oxygen and nourishment are carried by the blood to all body cells. Blood is made in the bone marrow (a soft spongy tissue within our bones). Whole blood is made up of red blood cells, white blood cells, platelets and clotting factors, as well as liquid called plasma. Various substances, such as proteins, salts and sugar, are also carried within the plasma.

Children who receive chemotherapy or whose disease affects the bone marrow may have many changes in blood counts. When your child receives chemotherapy, the blood counts will be checked often.