Essential Thrombocythemia (ET) is a chronic myeloproliferative neoplasm (MPN) characterized by an increased number of platelets in the blood. Most commonly diagnosed in women over the age of 50, ET is associated with a proliferation of platelet precursors in the bone marrow and complications frequently include blood clotting and/or bleeding.
http://www.mpnresearchfoundation.org/Essential-Thrombocythemia

