Essential thrombocythemia is a rare disorder in which the body produces too many blood platelets. This condition is associated with signs of fatigue, lightheadedness, headaches and vision changes. It also increases the risk of blood clots.
Essential thrombocythemia is more common in people aged 50 or over and slightly more common in women. It can also develop in young people.
Essential thrombocythemia is a chronic condition without a cure. A mild form of the disease may not require treatment. However, a severe type of the condition may require medications that lower platelet count, blood thinners or both.
The primary indication of essential thrombocythemia is the development of a blood clot (thrombus) that occurs most often in the brain, hands or feet.
Symptoms depend on where the clot forms and may include:
- Dizziness or lightheadedness
- Chest pain
- Temporary vision changes
- Numbness or tingling in the hands or feet
- Redness, throbbing and burning pain in the hands and feet
- Mildly enlarged spleen
Less commonly, essential thrombocythemia may cause bleeding (especially if the platelet count is extremely high). Bleeding may be in the form of:
- Bleeding from the mouth or gums
- Bloody stool
If a blood clot occurs in the arteries that supply the brain, it may cause a transient ischemic attack (TIA) or stroke. A TIA or ministroke is a temporary interruption of blood flow to part of the brain.
The symptoms of a stroke develop suddenly and include:
- Weakness or numbness of the face, arm or leg, usually on one side of the body
- Difficulty speaking or understanding speech (aphasia)
- Blurred, double or decreased vision
The bone marrow contains stem cells that can become red blood cells, white blood cells or platelets (thrombocytes). Platelets stick together and help blood form clots that stop bleeding when a blood vessel is damaged (ex. Cuts and scrapes).
In essential thrombocythemia the bone marrow makes too many platelet-forming cells (megakaryocytes). The excess platelets may malfunction, leading to abnormal clotting or bleeding.
The exact cause of essential thrombocythemia is unclear. Approximately 80% of people with the disorder have an acquired gene mutation that contributes to the disease.
A high platelet count that is caused by an underlying condition such as an infection or iron deficiency is known as reactive or secondary thrombocythemia. This form of thrombocythemia has a lower risk of blood clots and bleeding.
People with essential thrombocythemia who are older are at risk of complications, as are people who've had prior blood clots or bleeding problems related to the disease.
The abnormal blood clotting of essential thrombocythemia can lead to a variety of potentially serious complications, including:
- Pregnancy complications: uncontrolled thrombocythemia may lead to miscarriage and other complications.
- Stroke: a blood clot that block blood flow to the brain can cause a stroke.
- Heart attack: a blood clot that restricts blood flow to the heart can cause a heart attack.
Essential thrombocythemia may also cause bleeding with significant blood loss. In rare cases, people with essential thrombocythemia may later progress to the following life threatening diseases:
- Acute myelogenous leukemia: a type of white blood cell and bone marrow cancer with rapid progression.
- Myelofibrosis: a progressive bone marrow disorder that results in bone marrow scarring, leading to severe anemia and enlargement of the liver and spleen.
Treatment of essential thrombocythemia depends on the risk of blood clotting or bleeding episodes. No such signs or symptoms may indicate that no treatment is necessary but rather regular monitoring and checkups.
Medications may be prescribed if the individual is older than 60 and has had previous blood clots or TIAs or has had cardiovascular risk factors such as high cholesterol, high blood pressure and diabetes.
A medical procedure known as platelet pheresis is used in emergencies such as a stroke or dangerous blood clotting. The procedure temporarily lowers the platelet count.