What causes essential thrombocythemia? 

ET happens because of changes in genes, called mutations. These changes usually develop over a lifetime instead of being passed down from parents, or inherited. 

Most people with ET have mutations in a gene called JAK2. Almost one-quarter have mutations in a gene called CALR, and a few have mutations in another gene, MPL. Some people have mutations in other genes, most often TET2, ASXL1, DNMT3A, and SF3B1.²  These genetic changes send signals that tell the bone marrow to make too many platelets. 

What are essential thrombocythemia symptoms? 

People with ET may not feel sick. ET is often discovered during a routine blood test that shows a high platelet count.¹ 

When ET does cause symptoms, they can include headaches, dizziness, tiredness, night sweats, problems concentrating, or pain in the hands and feet. Some people feel cold sensations, notice a blue tint to their fingers and toes, or have vision problems.¹˒³  

Some people with ET experience more serious problems such as blood clots, which can cause chest pain, shortness of breath, or leg swelling. Others might have easy bruising, nosebleeds, or heavy periods when platelet counts rise.¹˒³  There are other ET symptoms, so tell your doctor about any changes. Because ET can affect people differently, it's important to speak with your doctor about any symptoms or changes. 

How is essential thrombocythemia diagnosed? 

ET is often discovered during a routine blood test that shows a high platelet count.¹  If your blood test shows a high platelet count, your doctor may refer you to a hematologist – a doctor who specializes in blood disorders. They will run additional tests to determine what's causing your high platelet count.¹˒⁴  

Doctors use specific diagnostic criteria to confirm essential thrombocythemia. They look at your platelet count, bone marrow appearance, and gene mutations and check for other blood conditions. When all the pieces fit together, they can diagnose ET.⁴ 

Before diagnosing ET, doctors need to rule out other reasons for high platelets. They will test for iron deficiency, infections, inflammation, and other blood diseases that can cause high platelet counts.¹ 

Your hematologist will test your blood for gene mutations – changes in the JAK2, CALR, and MPL genes and possibly others. Finding one of these mutations helps confirm the ET diagnosis, though not everyone with ET has one.¹˒² 

Your doctor needs to take a small sample of bone marrow in a procedure called a bone marrowbiopsy. This helps them see what's happening inside your bone marrow "factory," and make sure it's really ET and not another condition.¹˒⁴ 

Post-ET myelofibrosis 

Over time, a small number of people with ET (about 1 out of 10) may develop a related condition called post-ET myelofibrosis. This happens when scar tissue builds up in the bone marrow, which can cause anemia, fatigue, and an enlarged spleen. 

Understanding your ET diagnosis and moving forward 

Getting an ET diagnosis can feel overwhelming, but remember that many people with ET live normal, healthy lives. Your health care team will explain what the diagnosis means for you personally and help you understand the next steps in your care.1 Once ET is diagnosed, you can work with your health care team on a treatment plan. Understanding your ET is an important step towards managing it successfully.¹

Managing and treating essential thrombocythemia (ET) 

The goals of managing essential thrombocythemia (ET) are to reduce the risk of blood clots and bleeding, prevent heart attack and stroke, manage symptoms,and help you maintain a good quality of life.¹  You can work with your healthcare team to create a treatment plan that fits your specific needs. 

The right treatment depends on several factors. Your doctor will assess your risk for blood clots based on your age, whether you've had any before, and whether you have certain gene mutations, like JAK2, CALR, or MPL.² 

Essential thrombocythemia risk categories 

Doctors group ET into risk categories. Very low risk means you're under 60 with no JAK2 mutation and no history of blood clots. Low risk is under 60 with the JAK2 mutation and no clots. 

Intermediate risk means you are over 60 but do not have a JAK2 mutation or blood clots. High risk means you are over 60 with a JAK2 mutation and have had blood clots.¹˒⁴ Your risk level helps determine the best treatment. 

Lifestyle changes and managing other health conditions when you have ET 

No matter your risk level, healthy lifestyle choices are important. Regular exercise, healthy weight, a balanced diet, reducing stress, and not smoking all help reduce the risk of blood clots and improve your overall health.² 

It's important to manage any other health conditions that raise your risk of heart problems and blood clots, such as high blood pressure, diabetes, or high cholesterol.¹

Low-dose aspirin for essential thrombocythemia 

One ET treatment is low-dose aspirin, which helps keep platelets from sticking together and forming clots. Aspirin can also relieve burning or tingling in your hands and feet, which some people with ET experience.¹ However, if your platelet count is very high, over 1 million, your doctor may not recommend aspirin because it can increase your risk of bleeding. 

Cytoreductive therapy for essential thrombocythemia 

Medications called cytoreductive therapies are another option. They help reduce the number of platelets your bone marrow makes and can help symptoms.¹ 

Cytoreductive therapies include hydroxyurea, which is a medication that slows down how quickly your bone marrow makes blood cells, including platelets. You take it by mouth, and your doctor adjusts the dose based on your blood counts.¹˒³ 

Your doctor might prescribe anagrelide to reduce platelet production if hydroxyurea doesn't work well or causes side effects you can't tolerate.¹˒³ You take anagrelide as a daily capsule. The dose is adjusted to keep your platelets at a safe level. It can affect the heart, so it may not be a good option if you have heart rhythm problems. 

Interferon therapy for essential thrombocythemia 

Pegylated interferon helps control blood cell production in a different way. It's given as an injection you can do at home.¹˒⁴ This treatment is considered safer or preferred when treatment is needed during pregnancy, so it's often used for younger patients or women who are pregnant or planning to become pregnant. 

Newer therapies for advanced disease 

Over time, a small number of people with ET (about 5 to 10 out of 100) may develop a condition called post-ET myelofibrosis, where scar tissue builds up in the bone marrow. If this happens, your doctor will talk with you about different treatment options, since management for myelofibrosis is different from ET.⁴ 

Regular monitoring 

No matter what treatment you receive, regular checkups are essential. Your healthcare team will check your blood counts, blood pressure, and cholesterol levels. They will also check for signs of an enlarged spleen and make sure your treatment is working well.¹ It's also important to track your symptoms over time so you can notice any changes. Tell your team about any new symptoms right away. 

Clinical trials and research for essential thrombocythemia 

Researchers are developing new ET treatments. Talk with your doctor about whether a clinical trial might be right for you. Organizations like the MPN Research Foundation and National Cancer Institute have information on available trials. 

Quality of life and moving forward with essential thrombocythemia 

Living with ET is about more than just your blood counts. Your treatment should help you feel better and do the things you enjoy. Tell your doctor if you have fatigue, difficulty concentrating, or other symptoms that affect your daily life.¹ You may need additional support or an adjustment in your treatment. 

With proper monitoring and treatment, many people with ET can live long, full lives.¹˒³  Stay informed about your condition, work closely with your healthcare team, and remember that you're not alone on this journey. 

Disclaimer: The information provided is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always consult your doctor about any questions you may have regarding a medical condition. 

“Understanding and Diagnosing ET” References

1. MPN Research Foundation. What is essential thrombocythemia? 
   https://mpnresearchfoundation.org/essential-thrombocythemia-et

2. Tefferi A, Vannucchi AM, Barbui T. Essential thrombocythemia: 2024 update on diagnosis, risk stratification, and management. Am J Hematol. 2024 Apr;99(4):697-718. 

3. Thapa B, Fazal S, Parsi M, Rogers HJ. Myeloproliferative neoplasms. [Updated 2023 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. 
   https://www.ncbi.nlm.nih.gov/books/NBK531464

4. National Comprehensive Cancer Network (NCCN). NCCN Guidelines for Patients: Myeloproliferative neoplasms. [2024] 
   https://www.nccn.org/patients/guidelines/content/PDF/mpn-patient.pdf

“Managing and Treating ET” References

1. MPN Research Foundation. Managing and treating essential thrombocythemia. 
   https://mpnresearchfoundation.org/essential-thrombocythemia-et

2. Tefferi A, Pardanani A. Essential thrombocythemia: 2024 update on diagnosis, risk stratification, and management. Am J Hematol. 2024;99(4):697-719. 

3. Tefferi A, Vannucchi AM, Barbui T. Essential thrombocythemia treatment algorithm 2018. Blood Cancer J. 2018;8(1):2. 

4. Masarova L, Chifotides HT. How I individualize selection of JAK inhibitors for patients with myelofibrosis. Blood. 2025;145(16):1724-1737. 3,5