Essential thrombocythemia is a chronic disease common in people over age 50 and slightly more common in women. Young people can develop it as well. It is characterised by the overproduction of platelets by megakaryocytes in the bone marrow. Essential thrombocythemia is an uncommon disorder where the body produces too many blood platelets. This condition may cause to feel fatigued, lightheaded and to experience headaches and vision changes. It also increases the risk of blood clots.
The greatest health risk in patients with ET is an increased risk of developing blood clots. Blood clots can be in the deep vessels of the legs or lungs; ET patients are also more likely to experience strokes and heart attacks. ET patients can develop clots elsewhere, including within the abdomen, an otherwise rare site for clots to form. The risk of clotting increases with age, and disease-associated risks may be quite different for children than for adults, with children generally being at low risk for clots and other problems related to ET.
A normal platelet count ranges from 150,000 to 450,000 platelets per microliter of blood. In primary thrombocythemia, bone marrow makes too many platelet-forming cells (megakaryocytes). The excess platelets may not function normally, leading to abnormal clotting or bleeding. Having a high platelet count can cause blood clots to develop in the body, typically in the hands, feet, and brain. This may produce symptoms such as dizziness, headache, or numbness in the extremities.