Essential thrombocytosis

Overview

Essential thrombocytosis (ET, also known as essential thrombocythemia) is a rare chronic blood disorder characterized by the overproduction of platelets by megakaryocytes in the bone marrow in the absence of an alternative cause. In some cases this disorder may be progressive, and rarely may evolve into acute myeloid leukemia or myelofibrosis. It is one of four myeloproliferative disorders.

Symptoms

* Bleeding from the gastrointestinal tract * Bleeding from the gums * Bloody stools * Dizziness * Easy bruising * Enlarged lymph nodes (rare) * Headache * Nosebleeds (epistaxis) * Numbness of hands or feet * Prolonged bleeding from surgical procedures or tooth extraction * Ulcers on fingers or toes

Causes

Primary thrombocythemia is a slowly progressing disorder, caused by overgrowth of a type of cell that is a precursor of blood cells. Although the platelets are primarily affected, the red blood cells and white blood cells are also involved. The disease has similarities to polycythemia vera, chronic myelogenous leukemia, and myelofibrosis. Usually it affects people in middle age. Bleeding can occur from the gastrointestinal tract, respiratory system, urinary tract, or skin. The formation of blood clots (thrombosis), may occur with bleeding episodes. It may even cause strokes in some people. Risk factors are unknown. The incidence is about 3 out of 100,000 people.

Prognosis

The outcome varies. Some people have prolonged periods without complications, while complications related to hemorrhage and thrombosis lead to death in others.

Treatment

If a patient has life-threatening complications, platelet pheresis, a procedure to remove platelets from the blood directly, can rapidly decrease the platelet count. Long-term decrease of the platelet count using medications can reduce both bleeding and clotting complications. Most common medications include hydroxyurea, interferon-alpha, or anagrelide. For patients with a known clotting tendency, aspirin may help decrease clotting episodes. Some patients do not need any treatment