Essential thrombocythemia (ET) is an uncommon disorder in which your body produces too many blood platelets (thrombocytes). It's also known as primary thrombocythemia (throm-bo-sigh-THE-me-uh). Essential thrombocythemia is one of a group of diseases of the blood and bone marrow known as myeloproliferative neoplasms.
The most common symptoms of essential thrombocythemia include headache, lightheadedness, vision changes, and tingling, numbness or burning pain in the hands and feet. Essential thrombocythemia most often occurs in people over age 50 and is more common in women.
You may not need treatment for essential thrombocythemia if you're not experiencing symptoms. If you have abnormal blood clotting or bleeding, however, medications can help you avoid potentially serious complications.
Many people with essential thrombocythemia have no signs or symptoms. The first indication you have the disorder may be the development of a blood clot (thrombus). Although clots can develop anywhere in your body, with ET, they occur most often in your brain, hands and feet.
Signs and symptoms depend on where the clot forms. They include:
Less commonly, ET may cause bleeding, especially if your platelet count is extremely high (more than 1 million platelets per microliter of blood). Bleeding may take the form of:
A blood clot may cause a transient ischemic attack (TIA) — a temporary interruption of blood flow to part of the brain — or stroke. Signs and symptoms develop suddenly and include:
When to see a doctor
If you develop signs or symptoms of a TIA or stroke, such as numbness or paralysis on one side of your body, seek medical attention immediately.
Bone marrow — spongy tissue inside your bones — contains stem cells that can become red blood cells, white blood cells or platelets. Platelets travel through your blood vessels. They stick together to form clots that stop the bleeding when you damage a blood vessel, such as when you get a cut. A normal platelet count ranges from 150,000 to 450,000 platelets per microliter of blood.
If you have essential thrombocythemia, your bone marrow makes too many platelet-forming cells (megakaryocytes), which release too many platelets into your blood. The excess platelets may not function normally, leading to abnormal clotting or bleeding.
The exact cause of ET and other myeloproliferative neoplasms isn't known. About half the people with the disorder have a mutation of the Janus kinase 2 (JAK2) gene. Other gene mutations also have been associated with ET. The role of these mutations in causing the disease is still being investigated. A rare form of thrombocythemia is inherited.
A high platelet count that's caused by an underlying condition such as an infection or iron deficiency is called reactive or secondary thrombocytosis.
The abnormal blood clotting of essential thrombocythemia can lead to a variety of potentially serious complications, including:
Essential thrombocythemia can also cause bleeding (hemorrhage) with significant blood loss. A small minority of people with ET may later develop acute leukemia or myelofibrosis, both of which can be life-threatening:
Preparing for your appointment
You may find out you have essential thrombocythemia after a routine blood test shows a high number of platelets. Or you may see your doctor because of symptoms related to blood clotting or bleeding.
Besides taking your medical history, examining you physically and running tests, your doctor may ask you about factors that could affect your platelets, such as recent medical procedures, blood transfusions or infections. Your doctor may refer you to a doctor who specializes in blood diseases (hematologist).
Because appointments can be brief, and because there's often a lot of ground to cover, it's a good idea to be well prepared. Here's some information to help you get ready, and what to expect from your doctor.
What you can do
Your time with your doctor is limited, so preparing a list of questions will help you make the most of your time together. List your questions from most important to least important in case time runs out. For essential thrombocythemia, some basic questions to ask your doctor include:
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions that arise during your appointment if you don't understand something or need more information.
Tests and diagnosis
Blood tests that can help confirm a diagnosis of essential thrombocythemia include:
If your blood count is above 450,000 platelets per microliter of blood, your doctor will look for an underlying condition. If there's no evident cause of your high platelet count, and it remains high over time, your doctor may suggest a bone marrow test. The two types of bone marrow tests provide different but complementary information about your blood cells. Often they're done together.
Treatments and drugs
Treatment of essential thrombocythemia depends on your risk of blood-clotting or bleeding episodes. If you're younger than 60, have had no signs or symptoms and have no other risk factors for developing blood clots, such as smoking, you may simply need periodic medical checkups. If you're older than 60 and have had previous signs and symptoms of blood clots, your doctor likely will prescribe medication or a medical procedure to lower your platelet count. Your doctor may also recommend treatment if you have cardiovascular risk factors, such as high cholesterol, high blood pressure or diabetes.
Drugs that reduce the platelet count and are commonly used to treat ET include:
Lifestyle and home remedies
Take extra care to reduce your risk of developing blood clots if you have essential thrombocythemia. Healthy lifestyle habits can lower your risk of developing conditions that may contribute to blood clotting. These conditions include diabetes, high blood pressure and high blood cholesterol. Take steps to:
If your ET increases your tendency to bleed, take extra precautions to keep from injuring yourself. Follow these suggestions:
Last Updated: 2010-07-16
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