Tests and treatment for essential thrombocythaemia (ET)

The first test to diagnose essential thromboycthaemia (ET) is a blood test. This will check the number of platelets in your blood. In ET there is an abnormally high level of platelets.

If the first blood test suggests you have ET, you might have another blood test to look for a change in a gene Open a glossary item called JAK2. The JAK2 gene makes a protein that controls how many blood cells the stem cells make. A fault with your JAK2 gene means the stem cells can start producing platelets when they're not meant to. Around 60 in 100 people (around 60%) with ET have a fault in the JAK2 gene.

You might also have a blood test to check for gene changes in the CALR and MPL genes. Changes in these genes are also linked to ET.

Doctors are learning more about genetic changes all the time. You might have tests for other gene changes.

Other tests

Other tests you might have include:

  • a bone marrow test
  • a chest x-ray
  • an ultrasound scan of your tummy (abdomen), to check the size of your spleen

Treatment for ET

Treatment for ET aims to reduce the number of platelets. This helps to control your symptoms and to prevent any more serious problems. Your team will decide if you are at low or high risk of developing blood clots. This helps your team decide the best treatment for you.

You might have one or more treatments.

Low risk of developing blood clots

People who are low risk are under 60 years old and have a lower platelet count. Treatment for low risk ET is usually low dose aspirin.

High risk of developing blood clots

People in the high risk group tend to:

  • have had blood clots or bleeding before
  • smoke
  • have high blood pressure
  • have a platelet count of over 1500 x 10 9/l (your doctor can tell you your platelet count)
  • have a JAK2 gene change

People who tend to be high risk are also over 60 years old.

Treatments include:

  • low dose aspirin
  • oral chemotherapy such as hydroxycarbamide
  • anagrelide
  • interferon alpha

Types of treatment

Low dose aspirin

You take aspirin as a tablet. This can help to lower the number of platelets in the blood.


Chemotherapy uses cell killing (cytotoxic) drugs to destroy the extra platelets. The drugs work by disrupting the growth of cells and stopping them from dividing. The most common type of chemotherapy doctors use to treat ET is hydroxycarbamide. It is a tablet. There may be a small increase in risk of developing a leukaemia if you take hydroxycarbamide for a long time.

Another type of chemotherapy is busulfan. This is usually used in very elderly people who cannot take hydroxycarbamide. We know from research that it increases the risk of developing leukaemia if you take it for long periods of time. So, you might take it for a while and then stop for a period of time before starting again.


Anagrelide reduces the number of platelets. You take it as a capsule.

Doctors use it to treat ET when hydroxycarbamide is no longer working. Or you may have the two drugs together. Anagrelide does cause side effects that some people find difficult to cope with. These include:

  • breathlessness and tiredness from a low level of red blood cells (anaemia)
  • a racing heart
  • headache
  • feeling sick
  • heart problems

The side effects of anagrelide usually settle within a couple of weeks of starting treatment. Speak to your doctor if you are having any problems with side effects. 

Interferon alpha

Interferon is a type of a targeted treatment.

It can help to control the number of platelets. You usually have it as an injection under the skin, about 3 times a week. Side effects of interferon include flu like symptoms and tiredness. You might have pegylated interferon. It stays in the body for longer and so you usually only have this injection once a week.

Radioactive phosphorus

Radioactive phosphorus (P-32) is a type of internal radiotherapy.

Your bone marrow absorbs the radioactive phosphorus and gets a dose of radiation. The radiation slows down the number of platelets made. Very little radiation goes to the rest of the body.

Extra support

You might need extra treatment or support from your specialist team sometimes, such as:

  • during pregnancy or childbirth
  • if you are having an operation

Healthy Lifestyle

Your healthcare team might discuss ways to maintain a healthy lifestyle and help with stopping smoking if you need it.

We have information on healthy diet and lifestyle on our causes of cancer and reducing your risk pages.

Research and clinical trials

Researchers are trying to improve the diagnosis and treatment of essential thrombocythaemia.

Last reviewed: 
28 May 2020
Next review due: 
28 May 2023
  • Pan-London Haemato-Oncology Clinical Guidelines, Acute Leukaemias and Myeloid Neoplasms Part 4: Myeloproliferative Neoplasms

    RM Partners, South East London Cancer Alliance, North Central and East London Cancer Alliance, 2020

  • Essential Thrombocytosis

    BMJ Best Practice, Accessed May 2020

  • Essential Thrombocythemia

    C G Solomon

    New England Journal of Medicine, 2019. Volume 381

  • Electronic Medicines Compendium

    Accessed May 2020

  • Myeloproliferative Neoplasms

    National Comprehensive Cancer Network, 2020

  • Modification of Diagnostic Criteria for Essential Thrombocythaemia

    British Society for Haematology Guidelines, 2014

Related links