Tests and treatment for polycythaemia vera (PV)

Polycythaemia vera (PV) is a rare blood cancer that affects the bone marrow. It causes your body to make too many red blood cells.

To find out if you have polycythemia vera your doctor will do several tests. They will also examine you and ask about your general health.

Blood tests

The first test to diagnose polycythaemia vera (PV) is a blood test. This is to check:

  • the number of red blood cells
  • the number of platelets
  • the number of white blood cells
  • the haematocrit level

The haematocrit level is the amount of space the red blood cells take up in the blood. When there are more red blood cells Open a glossary item they take up more space and so the haematocrit level is higher.

Some people with PV have an increase in the number of platelets Open a glossary item. And some people may have an increased number of white blood cells Open a glossary item.

You may also have other blood tests to check your general health. These might include blood tests look kook at:

  • your iron levels
  • how well your liver is working
  • how well your kidneys are working
  • the levels of a blood cell growth factor called erythropoietin (EPO)

JAK2 gene 

If the first blood test suggests you have PV, 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 red blood cells when they're not meant to.

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
  • a test to measure the oxygen level in your blood (pulse oximetry)
  • a CT scan
  • an MRI scan

We have more information about some of these tests on our tests and scans page.

Treatment for polycythaemia vera

Treatment for PV aims to reduce the number of red blood cells. And reduce the risk of developing more serious problems such as blood clots. 

You might have more than one of these treatments.

The treatment you have is individual. Your healthcare team works out if you have a low risk or a high risk of developing a blood clot. This helps them decide the best treatment for you.

Your doctor and nurse will explain the treatment and any possible side effects you might have.

Doctors use a number of factors to work out your risk, these include if you: 

  • have had blood clots before

  • smoke

  • have high blood pressure

  • have diabetes

  • have high cholesterol levels

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

Treatment if you are at low risk for blood clots


This is a simple procedure that involves removing some of your blood. It is sometimes called phlebotomy. This helps to keep the haematocrit levels low. How much is taken depends on your blood test results.

The blood that is removed contains red blood cells, white blood cells, and platelets. Your body naturally replaces these but it takes longer to replace your red blood cells. This means, for a while your blood is not as thick.

You may have this regularly to begin with. For example, you might need to do this once a week. It’s likely you will have it less often over time and it can be repeated as often as you need.

Low dose aspirin

PV can raise the number of platelets in your blood. This can cause problems with blood clots. Low dose aspirin can lower your risk of getting a blood clot. You take it as a tablet.

A common side effect of low dose aspirin is indigestion Open a glossary item. You may also notice you bleed more easily than usual. For example, you might bruise more easily or have nosebleeds. Your nurse and doctor will explain all side effects and who to contact if you have any questions or concerns. 

Treatment if you are at high risk for blood clots

For a high risk of developing blood clots, you may have treatment to control your blood cell levels. The treatments aim to make the blood counts normal.

This is known as cytoreduction. There are several different drugs used as cytoreductive treatments.


Hydroxycarbamide is a chemotherapy drug known as an anti metabolite. These drugs stop cells making and repairing DNA Open a glossary item. Cancer cells need to make and repair DNA to grow and multiply.

Hydroxycarbamide has several possible side effects. There is a small increase in the risk of developing a leukaemia if you have this treatment repeatedly over a long time. Another side effect of hydroxycarbamide is the development of skin cancer.

Peginterferon alfa 2a

This is a treatment that helps to reduce the rate at which blood cells are made. It can help with the symptoms of PV, especially itching. Peginterferon alfa 2a is given as an injection. Side effects include flu-like symptoms and tiredness. It might also affect your general mood. Changes to your mood can include irritability and depression. 


Ruxolitinib is a type of targeted cancer drug. It works by blocking the effects of the JAK2 mutation found in people with PV.

You might have this if you can’t have hydroxycarbamide, or it no longer works in treating your PV.  Side effects of ruxolitinib include:

  • weight gain
  • increased risk of infection
  • skin cancer 


You might have a chemotherapy drug called busulfan. You might have busulfan if you can’t have hydroxycarbamide. This may be because you are allergic to it or or it’s not working for you.


When red blood cells are broken down by the body they produce uric acid. If you have too much uric acid in your blood it can collect in the joints and cause painful swelling, called gout. Allopurinol lowers the amount of uric acid in the blood and also helps to reduce the symptoms of gout.

Anagrelide with other cytoreductive drugs

You might have anagrelide together with other cytoreductive drugs if your platelet levels are abnormal and other treatments are not working.

This treatment is not suitable for everyone. Your healthcare team will give you more information about this if it's suitable for you.

Other treatments 

Alongside the treatments listed above you might also have:

  • low dose aspirin to lower the risk of blood clots
  • venesection to reduce the number of red cells in the blood

Extra support

You might need extra treatment or support from your specialist team.

Treatment during pregnancy 

There is a risk of complications including blood clots during pregnancy if you have PV. Your specialist will talk to you about treatments available and monitor you closely. Do also speak to your specialist if you plan to have a baby in the future. Some treatments may harm a developing baby. 

Having an operation or dental treatment

If you are having surgery or dental treatment for any reason, let your surgeon or dentist know you have PV and the treatment you may be taking. They may need to speak to your PV specialist. You might need to stop taking some treatments before your surgery. 

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.

Support and coping

We have information on support organisations that can help you cope with the diagnosis and treatment of polycythaemia vera.

  • Management of polycythaemia vera: a critical review of current data

    MF McMullin, BS Wilkins and CN Harrison

    British Journal of Haematology, 2016. Volume 172, Issue 3

  • Wintrobe’s Atlas of Clinical Hematology, 2nd edition

    BB Weksler, GP Schechter and S Ely

    Wolters Kluwer, 2018

  • A guideline for the diagnosis and management of polycythaemia vera. A British Society for Haematology Guideline
    M F McMullin and others
    British Journal of Haematology, 2019. Volume 185, Issue 1 pages: 198-198.

  • Polycythaemia vera (PV)

    P Bose

    BMJ Publishing Group Ltd. Updated April 2023. Accessed December 2023 

  • Polycythaemia/erythrocytosis

    National Institute for Health and Care Excellence (NICE). Last revised in April 2023

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. If you need additional references for this information please contact patientinformation@cancer.org.uk with details of the particular issue you are interested in.

Last reviewed: 
18 Dec 2023
Next review due: 
18 Dec 2026

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