Essential thrombocythaemia (ET)

What is ET?

Essential thrombocythaemia (ET) is a slow-growing blood cancer. It belongs to a group of conditions called myeloproliferative neoplasms (MPNs).

ET happens when your body makes too many platelets – the blood cells that help your blood to clot. This puts you at risk of blood clots and bleeding.

Who gets ET?

ET is rare. About 2,720 people are diagnosed with it each year in the UK.

Most people are diagnosed when they are 60 or over, but you can get ET at any age. It is more common in women than in men.

What are the signs and symptoms of ET?

Some people have blood clots or bleeding as the first sign that they have ET. But many people do not have any symptoms when they are first diagnosed. You may be diagnosed with ET from a blood test for something else and get signs and symptoms later as your ET progresses.

Symptoms vary widely from person to person. It depends on how ET affects you.

ET can slow your blood flow down because you have more platelets than you need. So, you may get symptoms due to poor blood flow in your small blood vessels. These can include:

• Numbness or pins and needles in your hands or feet
• Dizziness or light-headedness
• Headaches
• Blurred vision or partial loss of vision, like a blind spot
• Irregular, fast or fluttering heartbeat (palpitations)
• Chest pain
• High-pitched ringing in your ears (tinnitus)
• Burning, painful and red skin, usually in your feet (this can be harder to see on brown or black skin)

You may also develop general symptoms. These include:

• Extreme tiredness that does not get better after rest
• Difficulty sleeping
• Feeling low or sad
• Problems with concentration
• Night sweats
• Sexual problems
• Bone pain
• Itchy skin, especially after a warm bath or shower
• Losing weight without trying or wanting to
• Unexplained fever

“Looking back on it, I was having symptoms for 10 years before I was correctly diagnosed with ET. I had fatigue and bone pain, especially in my hands and feet.”

Josie, living with ET since 2015

You may develop a swollen spleen. If this happens, you may get symptoms like:

• Feeling full quickly when you eat
• Pressure or bloating in your tummy

Possible complications of ET

The main problems ET causes are blood clots and bleeding.

Blood clots

The most common complication of ET is blood clots.

You may get tiny clots in the veins beneath your skin, usually in your legs. Your skin in these areas may feel warm and itchy, and you may have pain, tenderness or swelling too.

You may have serious blood clots anywhere in your body:

• In your brain, they can cause a stroke or mini-stroke
• In your heart, they can cause a heart attack
• In your legs or arms, a clot may break free and travel to your lungs, causing a blockage (pulmonary embolism)
• In your tummy, they may damage your internal organs

Blood clots are the main cause of ill health in ET. They can be life-threatening, although this is rare.

Call 999 if you develop symptoms of a serious blood clot, including:

• Throbbing or cramping pain, swelling, warmth or redness in one leg or arm (redness may be harder to see on black or brown skin)
• Sudden breathlessness or sharp chest pain
• Coughing up blood
• Drooping on one side of your face
• Inability to hold both your arms up
• Problems speaking, like slurred or garbled speech

Bleeding

If your platelet levels get very high, you may develop bleeding. This can happen because high numbers of platelets can affect clotting factors in your blood.

Tell your haematology team if you have unexpected or unusual bleeding, such as:

• Nosebleeds
• Bleeding gums
• Heavy periods

How is ET diagnosed?

Some people do not have symptoms when they are first diagnosed. Your doctor may suspect you have ET from a blood test for something else. You will be referred to a blood specialist (a haematologist) at the hospital for further tests to confirm the diagnosis.

Your haematology team will diagnose ET based on:

• Blood tests
• Bone marrow tests

Your blood or bone marrow samples go to the lab for genetic testing. You may not need all these tests to be diagnosed with ET.

It can be difficult waiting for and coming to terms with test results. We are here for you if you need support.

ET risk groups

ET is often divided up into very low or low, medium (intermediate), and high-risk groups. They help your haematology team assess and monitor how much of a risk ET is to your health. They use your risk group to work out the best treatment plan for you.

Your haematology team will work out your risk group based on:

• Your age
• Whether you’ve had a blood clot already
• Whether you have a change to the JAK2 gene

In broad terms, risk groups reflect how likely you are to develop blood clots.

How is ET treated?

Your doctor will regularly monitor your ET and offer you treatment if you need it. Not everyone needs treatment straight away. If you are in a lower risk ET group, you may be on active monitoring instead.

Most treatments aim to control ET rather than cure it. If you need treatment, you may have medicines to:

• Prevent blood clots or bleeding, if you’re at risk
• Lower your platelet counts
• Manage your symptoms
• Control your blood counts
• Improve your quality of life

Your haematology team may recommend a single treatment or a combination of treatments. You can take these at home.

Medicines to prevent blood clots

Most people with ET take medicines that help prevent blood clots by stopping your platelets from sticking together. If your blood is ‘sticky’ and you’re at risk of blood clots, your team may recommend:

• Daily low-dose aspirin OR
• A medicine called clopidogrel

Many people with ET take daily low-dose aspirin.

Medicines to lower your platelet count

If you have a high platelet count or a high risk of blood clots or bleeding, you may have treatment to lower your platelets. Options include:

• A chemotherapy medicine called hydroxycarbamide. It comes as capsules that you take by mouth.
• Injections of a medicine called peginterferon. Your team may recommend this if you are young or pregnant. You usually have the injections once a week or less. You may be able to learn how to do them yourself.

If these do not work well, or you get side effects that are difficult to cope with, your team may suggest:

• A chemotherapy medicine called busulfan. This comes as tablets you take by mouth.
• A medicine called anagrelide. This comes as capsules you take by mouth.

Treatment for blood clots or bleeding

If you get a blood clot, you will have anti-clotting medicines to treat the clot and prevent future clots.

If you experience heavy bleeding, you will have treatment to stop the bleed and help replace the fluids you have lost.

Treatments to help with symptoms

Your haematology team may offer you supportive treatments. These help you deal with symptoms of your ET that can impact your quality of life, like headaches and itching, or with treatment side effects.

Supportive treatments include:

• Aspirin, a common treatment for ET, which can also help with symptoms like headache and burning, painful skin
• Antihistamines, which may help with itching or bone pain

Coping with side effects

Most medicines have side effects, including treatments for ET. Some can be temporary while your body gets used to a medicine. They vary depending on the treatment and from person to person, even with the same treatment. Some may cause health problems months or years after treatment.

Some of the more common side effects of ET treatments include changes to your blood counts and immune system. Some medicines may also increase your risk of skin cancer. So, you need to protect your skin from the sun and regularly check for skin changes.

Your haematology team should explain the most common side effects of the treatments they are offering you. They should also discuss severe side effects to be aware of, and how and when to seek help if you’re worried.

Active monitoring for ET

Some people don’t need treatment for ET straight away. If you don’t have any symptoms and your ET is not causing you any problems, you may be offered regular monitoring instead. This is called active monitoring or ‘watch and wait’.

It can be confusing and unexpected to be told you have ET but not be offered treatment.

However, if you are symptom-free and have lower-risk ET, it’s often better to wait to start treatment. You can still have treatment later, when you need it. You can avoid treatment side effects for as long as possible on active monitoring. And, ideally, enjoy a better quality of life.

If you are worried about your health or new or worsening symptoms at any time, contact your GP or haematology team. You don’t have to wait until your next check-up.

Lifestyle measures to help prevent blood clots

There are things you can do yourself to reduce your risk of getting blood clots. These lifestyle measures can help improve your quality of life and help with fatigue, too.

Making some small changes to your lifestyle can help you stay as well as possible after diagnosis, and before and during treatment. It is important to not change too much at once. Adopting a healthier way of living is about making small, manageable changes to your lifestyle.

“I strongly advise people with an MPN to take good care of their general health, watch their weight, exercise, don’t smoke, monitor their blood pressure and cholesterol – this also reduces their risk of blood clots, including stroke and heart disease.”

Professor Claire Harrison, Consultant and Deputy Chief Medical Officer

Looking after your heart health can help reduce your risk of blood clots. Some changes you can make to help reduce this risk include:

• Not smoking
• Maintaining a healthy weight
• Exercising at a level that works for you and how you are feeling
• Eating a healthy diet if you can
• Having regular tests to check your cholesterol and blood sugar levels
• Getting your blood pressure checked regularly

“Try to listen to your body and see what it feels like doing. Because you know your body better than anyone else.”

Linda, living with ET since 2025

The NHS has information and guidance on healthy eating, exercising and other ways to live well.

If you’re struggling to make lifestyle changes, ask your haematology team for advice. They should support you to look after your heart and offer you treatment if you have risk factors for heart disease.

Outcomes of ET

People with ET usually live long lives. But outcomes vary from person to person and depend on many different factors, including your risk group and your age at diagnosis.

Your consultant is the best person to advise you on your outlook. They can take account of your individual circumstances and test results.

“ET does not control your life. You control it with a positive outlook on your future.”

Lisa, living with ET since 2012

We have separate information on average outcomes for people with ET if you would like more detail. It is important to remember that we can only give general figures. We cannot say what will happen for you.

Transformation

Occasionally, ET changes or transforms into a different type of blood cancer.

ET may transform into any of these conditions:

• Polycythaemia vera (PV) – this is a type of MPN where your bone marrow makes too many red blood cells. Sometimes other blood cells, such as white blood cells, are affected too.
• Myelofibrosis (MF) – this is a type of MPN where your bone marrow becomes inflamed and scarred. This stops your bone marrow from making enough healthy blood cells.
• Acute myeloid leukaemia (AML) – this is a faster-growing blood cancer where immature white blood cells in your bone marrow multiply.

If your ET transforms, your symptoms may change, and so may your blood counts. Your haematology team will regularly check you for signs of transformation. If it happens, you will need different treatment.

Hear other people’s experiences

Our inspirational stories are personal accounts from people affected by blood cancer. They share their experiences, feelings or practical tips that helped them cope. Choose ‘essential thrombocythaemia’ in the dropdown list to find stories from people affected by ET.

Sources we used to develop this information

Abelsson J, Andréasson B, Samuelsson J, Hultcrantz M, Ejerblad E, Johansson B, Emanuel R, Mesa R, Johansson P. Patients with polycythemia vera have worst impairment of quality of life among patients with newly diagnosed myeloproliferative neoplasms. Leukemia & Lymphoma. 2013 Oct 1;54(10):2226-30. https://doi.org/10.3109/10428194.2013.766732 [Accessed Aug 2025]

Accurso V, Santoro M, Mancuso S, Vajana G, Tomasello R, Rotolo C, Camarda G, Mattana M, Siragusa S. Familial essential thrombocythemia: 6 cases from a mono‐institutional series. Clinical Case Reports. 2022 Mar;10(3):e05525. https://doi.org/10.1002/ccr3.5525 [Accessed Jul 2025]

Alvarez-Larrán A, Sant’Antonio E, Harrison C, Kiladjian JJ, Griesshammer M, Mesa R, Ianotto JC, Palandri F, Hernández-Boluda JC, Birgegård G, Nangalia J. Unmet clinical needs in the management of CALR-mutated essential thrombocythaemia: a consensus-based proposal from the European LeukemiaNet. The Lancet Haematology. 2021 Sep 1;8(9):e658-65. https://doi.org/10.1016/s2352-3026(21)00204-0 [Accessed Aug 2025]

Aspen. Busulfan 2 mg tablets – Summary of product characteristics. 12 March 2024. Available at: https://www.medicines.org.uk/emc/product/4653/smpc  [Accessed Aug 2025]

Barbui T, Tefferi A, Vannucchi AM, Passamonti F, Silver RT, Hoffman R, Verstovsek S, Mesa R, Kiladjian JJ, Hehlmann R, Reiter A. Philadelphia chromosome-negative classical myeloproliferative neoplasms: revised management recommendations from European LeukemiaNet. Leukemia. 2018 May;32(5):1057-69. https://doi.org/10.1038/s41375-018-0077-1 [Accessed Jul 2025]

Baumeister J, Chatain N, Sofias AM, Lammers T, Koschmieder S. Progression of myeloproliferative neoplasms (MPN): diagnostic and therapeutic perspectives. Cells. 2021 Dec 16;10(12):3551. https://doi.org/10.3390/cells10123551 [Accessed Sep 2025]

Cross NC, Godfrey AL, Cargo C, Garg M, Mead AJ, A British Society for Haematology Good Practice Paper. The use of genetic tests to diagnose and manage patients with myeloproliferative and myeloproliferative/myelodysplastic neoplasms, and related disorders. British Journal of Haematology. 2021 Nov;195(3):338-51. https://doi.org/10.1111/bjh.17766 [Accessed Sep 2025]

Duminuco A, Vaghela R, Virdee S, Woodley C, Asirvatham S, Curto-Garcia N, Sriskandarajah P, O’Sullivan J, de Lavallade H, Radia D, Kordasti S. QRISK3 score is predictive of thrombotic risk in patients with myeloproliferative neoplasms: chronic myeloproliferative neoplasms. Leukemia. 2025 Jul 24:1-7. https://doi.org/10.1038/s41375-025-02681-9 [Accessed Aug 2025]

Gangat N, Karrar O, Al-Kali A, Begna KH, Elliott MA, Wolanskyj-Spinner AP, Pardanani A, Hanson CA, Ketterling RP, Tefferi A. One thousand patients with essential thrombocythemia: the Mayo Clinic experience. Blood Cancer Journal. 2024 Jan 18;14(1):11. https://doi.org/10.1038/s41408-023-00972-x [Accessed Aug 2025]

Geyer HL, Andreasson B, Kosiorek HE, Dueck AC, Scherber RM, Martin KA, Butler KA, Harrison CN, Radia DH, Cervantes F, Kiladjian JJ. The role of sexuality symptoms in myeloproliferative neoplasm symptom burden and quality of life: An analysis by the MPN QOL International Study Group. Cancer. 2016 Jun 15;122(12):1888-96. https://doi.org/10.1002/cncr.30013 [Accessed Aug 2025]

Godfrey AL, Green AC, Harrison CN. Essential thrombocythemia: challenges in clinical practice and future prospects. Blood. 2023 Apr 20;141(16):1943-53. https://doi.org/10.1182/blood.2022017625 [Accessed Aug 2025]

Grinfeld J, Nangalia J, Baxter EJ, Wedge DC, Angelopoulos N, Cantrill R, Godfrey AL, Papaemmanuil E, Gundem G, MacLean C, Cook J. Classification and personalized prognosis in myeloproliferative neoplasms. New England Journal of Medicine. 2018 Oct 11;379(15):1416-30. https://doi.org/10.1056/NEJMoa1716614 [Accessed Aug 2025]

Haematological Malignancy Research Network (HMRN). Factsheets: Essential thrombocythaemia 2022. Available at: www.hmrn.org/factsheets#essential_thrombocythaemia [Accessed Aug 2025]

Haematological Malignancy Research Network (HMRN). Survival: Essential thrombocythaemia. Available at: https://hmrn.org/statistics/survival [Accessed Aug 2025]

Harrison CN, Bareford D, Butt N, Campbell P, Conneally E, Drummond M, Erber W, Everington T, Green AR, Hall GW, Hunt BJ. Guideline for investigation and management of adults and children presenting with a thrombocytosis. British Journal of Haematology. 2010 May 1;149(3). https://doi.org/10.1111/j.1365-2141.2010.08122.x [Accessed Aug 2025]

Harrison CN, Butt N, Campbell P, Conneally E, Drummond M, Green AR, Murrin R, Radia DH, Mead A, Reilly JT, Cross NC. Modification of British Committee for Standards in Haematology diagnostic criteria for essential thrombocythaemia. British Journal of Haematology. 2014 Nov 1;167(3). https://doi.org/10.1111/bjh.12986 [Accessed Aug 2025]

Harrison CN, Koschmieder S, Foltz L, Guglielmelli P, Flindt T, Koehler M, Mathias J, Komatsu N, Boothroyd RN, Spierer A, Perez Ronco J. The impact of myeloproliferative neoplasms (MPNs) on patient quality of life and productivity: results from the international MPN Landmark survey. Annals of Hematology. 2017 Oct;96(10):1653-65. https://doi.org/10.1007/s00277-017-3082-y [Accessed Aug 2025]

Medac Pharma LLP. Hydroxycarbamide medac 500 mg capsule, hard – Summary of product characteristics. 04 November 2024. Available at: https://www.medicines.org.uk/emc/product/254/smpc [Accessed Aug 2025]

Mesa RA, Miller CB, Thyne M, Mangan J, Goldberger S, Fazal S, Ma X, Wilson W, Paranagama DC, Dubinski DG, Naim A. Differences in treatment goals and perception of symptom burden between patients with myeloproliferative neoplasms (MPNs) and hematologists/oncologists in the United States: findings from the MPN Landmark survey. Cancer. 2017 Feb 1;123(3):449-58. https://doi.org/10.1002/cncr.30325 [Accessed Aug 2025]

National Comprehensive Cancer Network (NCCN). NCCN guidelines for patients: myeloproliferative neoplasms. National Comprehensive Cancer Network. 2024. Available at: https://www.nccn.org/guidelines/guidelines-detail?category=1&id=1477 [Accessed Aug 2025]

Neon Healthcare Ltd. Hydrea 500 mg hard capsules (hydroxycarbamide) – Patient information leaflet. November 2024. Available at: https://www.medicines.org.uk/emc/product/13886/pil [Accessed Aug 2025]

O’Sullivan J, Mead AJ. Heterogeneity in myeloproliferative neoplasms: Causes and consequences. Advances in Biological Regulation. 2019 Jan 1;71:55-68. https://doi.org/10.1016/j.jbior.2018.11.007 [Accessed Jul 2025]

Paz LD, Jouanneau-Courville R, Riou J. Leukemic evolution of polycythemia vera and essential thrombocythemia: genomic profiles predict time to transformation (vol 4, pg 4887, 2020). Blood Advances. 2020 Nov 24;4(22):5651-. https://doi.org/10.1182/bloodadvances.2020002271 [Accessed Aug 2025]

Rendo M, Cavacece C, Chung-ting JK, Beeler BW, Fenderson J, Beeler B. Familial essential thrombocythemia with novel MPL L502G and G208K mutations. Cureus. 2022 Mar 16;14(3). https://doi.org/10.7759/cureus.23220 [Accessed Jul 2025]

Robinson AJ, Godfrey AL. Low-risk essential thrombocythemia: a comprehensive review. Hemasphere. 2021 Feb 1;5(2):e521. https://doi.org/10.1097/HS9.0000000000000521 [Accessed Aug 2025]

Rungjirajittranon T, Owattanapanich W, Ungprasert P, Siritanaratkul N, Ruchutrakool T. A systematic review and meta-analysis of the prevalence of thrombosis and bleeding at diagnosis of Philadelphia-negative myeloproliferative neoplasms. BMC Cancer. 2019 Feb 28;19(1):184. https://doi.org/10.1186/s12885-019-5387-9 [Accessed Aug 2025]

Stuckey R, Ianotto JC, Santoro M, Czyż A, Perez Encinas MM, Gómez‐Casares MT, Noya Pereira MS, de Nałęcz AK, Gołos A, Lewandowski K, Szukalski Ł. Validation of thrombotic risk factors in 1381 patients with essential thrombocythaemia: A multicentre retrospective real‐life study. British Journal of Haematology. 2022 Oct;199(1):86-94. https://doi.org/10.1111/bjh.18387 [Accessed Aug 2025]

Szuber N, Vallapureddy RR, Penna D, Lasho TL, Finke C, Hanson CA, Ketterling RP, Pardanani A, Gangat N, Tefferi A. Myeloproliferative neoplasms in the young: Mayo Clinic experience with 361 patients age 40 years or younger. American Journal of Hematology. 2018 Dec;93(12):1474-84. https://doi.org/10.1002/ajh.25270 [Accessed Aug 2025]

Takeda UK Ltd. Xagrid 0.5mg hard capsule (anagrelide hydrochloride)  – Summary of product characteristics. 07 February 2023. Available at: https://www.medicines.org.uk/emc/product/3883/smpc [Accessed Aug 2025]

Tefferi A, Vannucchi AM, Barbui T. Essential thrombocythemia: 2024 update on diagnosis, risk stratification, and management. American Journal of Hematology. 2024;99:697-718. https://doi.org/10.1002/ajh.27216 [Accessed Aug 2025]

Vannucchi AM, Barbui T, Cervantes F, Harrison C, Kiladjian JJ, Kröger N, Thiele J, Buske C, ESMO Guidelines Committee. Philadelphia chromosome-negative chronic myeloproliferative neoplasms: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of Oncology. 2015 Sep 1;26:v85-99. https://doi.org/10.1093/annonc/mdv203 [Accessed Aug 2025]