What are myeloproliferative disorders?
Myeloproliferative disorders are diseases in which too many of certain types of blood cells are made in the bone marrow. The bone marrow is the spongy tissue inside the large bones in the body. The bone marrow makes red blood cells (which carry oxygen to all the tissues in the body), white blood cells (which fight infection), and platelets (which make the blood clot). There are six types of myeloproliferative disorders: chronic myelogenous leukemia, polycythemia vera, chronic idiopathic myelofibrosis, essential thrombocythemia, chronic neutrophilic leukemia, and chronic eosinophilic leukemia. Chronic myelogenous leukemia affects the cells that are developing into white blood cells, called granulocytes. (Refer to the PDQ summary on Chronic Myelogenous Leukemia Treatment for more information.) Polycythemia vera means too many red blood cells are made in the bone marrow and build up in the blood. The spleen (the organ in the upper abdomen that filters the blood to remove old cells) may sw
