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Tests and treatment for essential thrombocythaemia (ET)

Find out about the diagnosis and treatment options for essential thrombocythaemia (ET). 

Getting diagnosed

You will have a blood test called a full blood count. This will check the number of platelets in your blood. In ET there’s an abnormally high level of platelets.

You will also have a blood test to check for genetic faults to the JAK2, CALR and MPL genes. Around 60% of ET patients have a fault in the JAK2 gene.

Other tests you may have include:

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

Decisions about your treatment

Treatment for ET aims to reduce the number of platelets. This helps to control your symptoms. The treatment you need will depend on your risk of developing blood clots. Doctors group people into 3 risk groups – high, intermediate and low.

High risk of developing blood clots

People who are at high risk tend to:

  • be over 60 years old
  • have had blood clots before
  • smoke
  • have high blood pressure
  • have a platelet count of over 1500 x 10 9/l
  • have a JAK2 gene change

Intermediate risk of developing blood clots

If you are at intermediate risk your treatment will depend on the symptoms you have and your general health.

Treatments include:

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

Treatment usually includes aspirin and chemotherapy.

Low risk of developing blood clots

People who are low risk are under 40 and have a lower platelet count. Treatment for low risk is usually low dose aspirin.

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 take it for a while and then stop for a period of time before starting again.


Anagrelide reduces the number of platelets. Doctors use it to treat ET when hydroxycarbamide is no longer working. Or you may have the 2 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 startinig treatment. Speak to your doctor if you are having any problems. 


Interferon is a type of a targeted cancer drug and helps to boost the immune system.

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. Pegylated interferon is being looked at in trials. It stays in the body for longer and so you usually only have this injection once a week.


Researchers are looking into new types of treatment to stop the JAK2 gene signalling to stem cells to make blood cells. These are called JAK2 inhibitors.

Researchers are also looking into how myeloproliferative disorders develop. Some of this research is suggesting that it may be better to group them depending on whether they are JAK2 positive or negative rather than whether they are ET, myelofibrosis or polycythaemia vera. We need more research to find out the best way to group them and what the best treatment is.

Last reviewed: 
19 Sep 2017
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