Essential thrombocythemia (ET) is a rare blood disease called a myeloproliferative neoplasm (MPN) that develops when the bone marrow doesn’t work normally and makes too many platelets. Too many platelets in the blood can form a blood clot and can cause a stroke, a heart attack or blood clots in the lungs (called a pulmonary embolism). In rare cases, too many platelets can cause bleeding problems. ET is a chronic disease, which means that it develops slowly over time.
It's unclear what causes ET, but most people with ET have a change, or mutation, in the JAK2 (Janus kinase 2) gene, the CALR (calreticulin) gene or the MPL (myeloproliferative leukemia) virus oncogene.
ET usually develops in people around 60 years old. It can also develop in younger people, especially women. Pregnant women with untreated ET have an increased risk of pregnancy complications, including miscarriage, the baby developing slower than normal during pregnancy and premature birth.
In rare cases, ET can develop into polycythemia vera (PV), myelofibrosis or acute myeloid leukemia (AML).
ET may not cause any symptoms. If you do have symptoms, they are often related to either blood clots or bleeding problems. The most common symptoms of ET include:
- pain, redness, swelling and warmth in the feet and legs
- tingling in the hands or feet
- easy bruising or bleeding
Many tests used to diagnose ET are used to diagnose leukemia. Diagnosis of ET is usually based on if the platelet count in the blood is high, if the bone marrow has a lot of platelet-forming cells (called megakaryocytes) and if JAK2, CALR or MPL gene mutations are found in the blood or bone marrow.
Your healthcare team will create a treatment plan just for you. The plan is based on your health and specific information about the disease. What you want is also important when planning treatment. The goal of treatment for ET is to prevent blood clots. Treatments for ET are given based on your risk of developing bleeding, blood clots and other complications.
Very low risk means that you have a very low risk of developing complications. You are considered very low risk if you are 60 years old or younger, you don't have a JAK2 gene mutation and you don't have a history of blood clots.
Low risk means that you have a low risk of developing complications. You are considered low risk if you are 60 years old or younger, you have a JAK2 gene mutation and you don't have a history of blood clots.
Intermediate risk means that you have a slightly higher risk of developing complications. You are considered intermediate risk if you are older than 60, you don't have a JAK2 gene mutation and you don't have a history of blood clots.
High risk means that you are likely to develop complications. You are considered high risk if you are any age with a history of blood clots, or you are older than 60 with a JAK2 gene mutation.
Treatments for very low risk and low risk ET @(Model.HeadingTag)>
If you have very low risk or low-risk ET, you may not need treatment right away. Your doctor may observe your situation and start treatment only if you start feeling symptoms or your situation gets worse.
Low-dose Aspirin may be offered for low-risk ET if you have a JAK2 mutation or cardiovascular risk factors (including obesity, smoking tobacco, high blood pressure or high cholesterol) or both. Aspirin may not be appropriate in all situations especially if you have a condition that increases your risk of bleeding. You may also be given Aspirin if you are pregnant to lower the risk of complications from ET.
Treatments for intermediate and high risk ET @(Model.HeadingTag)>
If you have intermediate or high-risk ET you may be offered drug therapy. The drugs used most often to treat ET include:
- hydroxyurea (Hydrea) – usually given as
- anagrelide (Agrylin)
- peginterferon alfa (Pegasys)
- ropeginterferon alfa
Low-dose Aspirin is usually given with drug therapy unless you have a symptom or condition that increases your risk of bleeding. You may also be given Aspirin if you are pregnant to lower the risk of complications from ET.
For more information on certain drugs, go to sources of drug information.
Clinical trials @(Model.HeadingTag)>
Talk to your doctor about clinical trials open to people with MPNs in Canada. Clinical trials look at new ways to prevent, find and treat diseases. Find out more about clinical trials.
Follow-up after treatment is an important part of healthcare. Follow-up for ET is often shared among the blood specialists (hematologists) and your family doctor. Your healthcare team will work with you to decide on follow-up care to meet your needs.
Don’t wait until your next scheduled appointment to report any new symptoms and symptoms that don’t go away.
Expert review and references
Kareem Jamani, MD, LMCC, FRCPC
Use Alberta Health Services. Essential Thrombocythemia. Edmonton: 2021: https://www.albertahealthservices.ca/.
Lal A . Medscape Reference: Essential Thrombocytosis . WebMD LLC ; 2021 : https://www.medscape.com/.
Liesveld J. Essential thrombocythemia. Merck Manual Professional Version. Kenilworth, NJ: Merck & Co, Inc; 2020: https://www.merckmanuals.com/en-ca/professional.
PDQ Adult Treatment Editorial Board. Chronic Myeloproliferative Neoplasms Treatment (PDQ®) – Health Professional Version. Bethesda, MD: National Cancer Institute; 2020: https://www.cancer.gov/.
National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Myeloproliferative Neoplasms (Version 1.2022) . 2022: https://www.nccn.org/home.
National Institutes of Health. MedlinePlus Genetics: Essential Thrombocythemia. Bethesda, MD: US Department of Health & Human Services; 2020: https://medlineplus.gov/genetics/.