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This booklet provides information about myeloproliferative neoplasms (myelofibrosis, polycythemia vera and essential thrombocythemia) and includes our Myeloproliferative Neoplasm Symptom Assessment Form to help you identify and keep track of your symptoms.
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What is essential thrombocythemia (ET)?
Essential thrombocythemia (ET) is a rare blood disease in which the bone marrow produces too many platelets. High numbers of platelets may lead to a thrombus, a blood clot that forms in a blood vessel, causing serious health problems such as a stroke, heart attack, or pulmonary embolism.
It is one of a related group of blood cancers known as “myeloproliferative neoplasms” (MPNs), in which cells in the bone marrow that produce blood cells develop and function abnormally.
On average, individuals with ET have a normal life expectancy if they are properly monitored and treated. In a small number of patients, the disease may transform to myelofibrosis, acute myeloid leukemia (AML); or less frequently, myelodysplastic syndrome (MDS).
You should be treated by a hematologist-oncologist, a specialist who treats people who have ET or other types of blood cancer.
ET does not generally shorten life expectancy; however, medical supervision is important to prevent or treat thrombosis, a serious complication that can affect vital organs such as the brain or the heart. Also, for untreated pregnant patients with ET, there is a risk to the survival of the fetus.
What should I do if I am diagnosed with ET?
- Talk with your doctor about your diagnostic tests and what the results mean.
- Learn how to choose a blood cancer specialist or treatment center.
- Talk with your doctor about all your treatment options, side effects, and the results you can expect from treatment.
- Ask your doctor whether a clinical trial is a good treatment option for you.
Learn more about communicating with your blood cancer specialist or find a list of suggested questions to ask your healthcare providers.
How does ET develop?
Stem cells form blood cells (white cells, red cells, and platelets). The DNA (genetic material) of a developing stem cell in the bone marrow undergoes a change (genetic mutation).
The mutated cell leads to uncontrolled blood cell production, especially platelets. Red cells and white cells are usually affected as well. There is mainly an overproduction of platelet-forming cells, called "megakaryocytes," in the marrow.
This results in the release of too many platelets into the blood. The platelets’ function is to start the process of forming a plug (clot) in response to blood vessel injury to prevent or minimize bleeding. When platelets are present in very high numbers, they may not function normally and may cause a blockage in blood vessels, known as a "thrombus." Less often, a high number of platelets can also cause bleeding problems.
Another word for platelet is "thrombocyte." The term "thrombocythemia" means an excess of platelets in the blood. The term "essential" indicates that the increase in platelets is an innate problem of blood cell production in the bone marrow.
"Secondary thrombocytosis" is the term for a condition that results in very high platelet counts in the blood in reaction to another problem in the patient's body, such as inflammatory disease, removal of the spleen, or iron deficiency in adults. A patient with secondary (or “reactive”) thrombocytosis should have a return to normal platelet count in the blood once the primary problem is treated successfully.
ET disease complications
In medicine, a complication is a medical problem that occurs in the course of a disease or after a procedure or treatment.
Possible complications of ET include:
Deep vein thrombosis (DVT)
Deep vein thrombosis (DVT) occurs when a blood clot (thrombus) forms in one or more of the deep veins in the body, usually in the legs. This can cause pain, swelling, and reddening in the affected area. If a blood clot from a deep vein breaks loose and travels to the lungs, it can become lodged in the lungs and block blood flow, causing a serious blockage called a pulmonary embolism. Symptoms of a pulmonary embolism include shortness of breath, chest pain, and cough.
Stroke
If a blood clot occurs in the arteries that supply blood to the brain, it may cause a stroke or a transient ischemic attack (TIA). A stroke is a loss of blood flow to part of the brain, which damages brain tissue. A TIA is a type of stroke that only lasts a few minutes when the blood supply to part of the brain is briefly blocked.
Heart attack
If a clot blocks blood flow to the heart, it can cause a heart attack. Without blood, tissue in the heart can lose oxygen and die. Symptoms of a heart attack include pain in the chest, neck, or back, as well as fatigue, dizziness, and an abnormal heartbeat.
Find facts and statistics for MPNs and other blood cancers.
Source: Myeloproliferative Neoplasms. Reviewed by John Mascarenhas, MD.
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