Polycythaemia vera (PV) is a rare slow-growing blood cancer where the bone marrow makes too many red blood cells. This can make the blood thicker than normal. Some people with PV also have too many white blood cells and platelets in their blood.
PV is more common in people aged over 40, and in men. It develops slowly and for most people it will not shorten their lives. But it can cause complications. The most common one is blood clots. If you have PV it is important to have regular check-ups. This means you can have treatment to prevent problems if needed.
To understand PV and its treatment, it can help to know more about your blood and bone marrow.
Having too many red blood cells in the blood is not always because of changes in the bone marrow. Some other conditions, such as lung disease or a kidney disorder, can cause an increase in red blood cells. This is called secondary polycythaemia.
Secondary polycythaemia can also be caused by:
- drinking large amounts of alcohol
- having high blood pressure.
The treatment of secondary polycythaemia is different from PV. It involves treating the condition that has led to the increased number of blood cells, or making lifestyle changes.
Having a high number of red blood cells does not always cause symptoms. Some people are diagnosed with PV after they have a blood test taken for another reason.
Possible symptoms of PV include:
- severe, migraine type headaches
- blurred vision
- itchy skin (often after a warm bath or shower)
- sweating more than usual
- redness, swelling and pain or changes in sensation in the hands or feet
- redness of the face
- bone pain.
Possible complications of PV
Some people also develop symptoms because of complications of PV.
The spleen sits on the left side of the tummy (abdomen), just under the ribs. It is usually about the size of a fist. The spleen:
- helps fight infection
- stores and breaks down blood cells.
PV can cause your spleen to grow bigger than normal. Sometimes this causes symptoms. These include discomfort on the left side of the tummy and feeling full quickly when eating.
Some people with PV have a higher risk of developing blood clots. Symptoms can happen because a blood clot (thrombosis) forms. If you have any symptoms you think may be caused by a blood clot, contact a doctor urgently. If you cannot speak to a doctor, call 999 for an ambulance or go to A&E.
People with PV can develop red, painful and swollen joints. This is caused by a condition called gout. Gout can happen when the body breaks down more blood cells than normal.
When the body breaks down cells it makes uric acid. Normally the kidneys remove this acid from the blood and pass it out of the body in urine (pee). If the body breaks down more cells than the kidneys can get rid of, uric acid builds up in the blood. Crystals that form from uric acid get into the joints and cause the symptoms of gout.
Gout usually affects the big toe, but other joints can be affected. Your doctor will check the level of uric acid in your blood. If it is higher than normal, they may give you tablets called allopurinol. Allopurinol prevents gout by helping your kidneys to get rid of uric acid.
Bleeding or bruising
Sometimes PV can cause abnormal bleeding. Bleeding may be heavier than normal and take longer to stop. This can cause symptoms such as:
- bruising easily
- abnormal vaginal bleeding
- bleeding gums
- very dark stools (poo) or dark vomit, caused by bleeding in the stomach or bowel.
Tell your doctor if you notice any signs of abnormal bleeding.
If you think you are bleeding from the stomach or bowel, or if bleeding is heavy or will not stop, contact a doctor urgently. If you cannot speak to a doctor, call 999 for an ambulance or go to A&E.
Rarely, PV can develop into acute leukaemia, which is a cancer of the white blood cells. Not everyone with PV has the same risk of developing leukaemia. For most people, PV remains stable for many years and does not affect how long you live for. Your doctor can tell you more about this.
You are usually diagnosed with PV by a doctor who specialises in treating blood disorders (haematologist). Your GP may have suspected PV based on the results of a blood test (full blood count). This test counts the number of red blood cells, white blood cells and platelets in the blood.
Your haematologist will usually arrange some tests for you before they diagnose PV. These help to rule out other conditions that can affect blood counts.
Blood test to check for a gene change
Genes carry the instructions a cell needs to work properly. Certain genes control how many blood cells the bone marrow makes.
A blood test can check for a change (mutation) in a gene called JAK2 that can cause PV. This gene helps control how many blood cells the bone marrow makes. About 95 out of 100 people with PV (95%) have a change in the JAK2 gene. This change happens in the cells over your lifetime. It is not a gene you were born with and it cannot be passed on in your family.
Other blood tests
You may have blood tests done to check:
- the levels of iron and vitamin B12 in your blood
- whether you make too much of a hormone called erythropoietin that encourages red blood cells to be made
- how much oxygen your blood is carrying (an oxygen saturation test).
Bone marrow test
Waiting for test results can be a difficult time. It may help to talk to your family, friends or specialist nurse.
Treatment for PV aims to reduce the number of red blood cells in the blood. This reduces symptoms and the risk of complications such as blood clots or gout. Your doctor will usually start by giving you a low dose of aspirin daily. They will check your condition by doing regular blood tests.
The treatment you have will depend on your risk of developing complications. Your doctor will assess if you have a low, medium or high risk. They will base this on:
- your age
- your symptoms
- your full blood count
- the thickness of your blood (haematocrit HCT)
- if you have had a blood clots before
- your general health
- if you have any other conditions, such as diabetes.
You may be invited to join a clinical trial looking at new ways of treating PV.
Reducing risk factors for heart disease and stroke
Because PV can cause blood clots, it is important to reduce your risk of heart disease and stroke. Your doctors and nurses will make sure any health conditions you have that can increase your risk are well controlled. This includes conditions such as:
- high blood pressure
- high cholesterol.
Your doctors and nurses will give you advice about any lifestyle changes you can make to help to reduce your risk. Doctors usually advise you to:
- stop smoking, if you smoke
- drink plenty of fluids
- eat healthily and be physically active
- keep to a healthy weight
- find ways of reducing stress.
The following treatments can be used for PV:
Aspirin affects the way platelets stick together and helps prevent blood clots. Some people may take it as part of their treatment.
One of the side effects of aspirin is an increased risk of bleeding and ulcers in the stomach. Certain types of painkillers, such as ibuprofen, can also cause stomach problems. Because of this, they may not be suitable for you while you are taking aspirin. If you need to take painkillers for any reason, ask your doctor for advice.
Removing blood (venesection)
Regularly removing about a pint (500ml) of your blood is a common treatment for PV. It reduces the number of red blood cells in your blood and makes your blood thinner.
The procedure is like donating blood. A nurse puts a needle into your vein. The needle is attached to a tube and a bag. Your blood flows through the needle and tube, into the bag. When they have collected enough of your blood the nurse removes the needle.
You may have a venesection every few weeks or months until your blood thickness is at the right level.
On the day you have your venesection, it is important to drink plenty of fluids. This helps to replace the fluid that has been removed.
Chemotherapy uses anti-cancer (cytotoxic) drugs to destroy cancer cells. It can be used to reduce the blood cell count in PV.
Hydroxycarbamide (HC) is the most commonly used chemotherapy drug to treat PV. It can cause side effects, which are generally mild.
Taking HC for a long time can increase your risk of getting skin cancer. It is important that you protect your skin from the sun. You also need to check for any changes in your skin during and after treatment with HC. Your haematologist or specialist nurse can tell you more about this.
Rarely, the chemotherapy drug busulfan may be used if other treatments have not worked well. The side effects are like the side effects of hydroxycarbamide. If you take busulfan for a long time, it may slightly increase your risk of developing leukaemia.
Chemotherapy may affect the development of an unborn baby. Doctors usually advise against getting pregnant or making someone pregnant during treatment and for a few months after. It is important to use effective contraception.
Chemotherapy may affect fertility. If this is a concern for you, talk to your doctor before treatment starts.
Interferon is a natural substance made by the body. It can also be made as a medicine. It slows down the rate at which the bone marrow makes blood cells.
Ruxolitinib is a targeted therapy drug. It targets genes that help the abnormal blood cells in PV to grow.
You may have this treatment if other treatments such as hydroxycarbamide and interferon are not reducing the thickness of your blood.
If you have had tuberculosis (TB) or hepatitis B or C in the past, ruxolitinib may make it active again. Your doctor will give you treatment to reduce the risk of this happening.
It is important to check with your doctor before having any vaccinations. This is because live vaccines may cause an infection in people taking ruxolitinib.
Ruxolitinib is not usually available through the NHS as a treatment for PV. We have more information about what can be done if a treatment is not available.
Radioactive phosphorus (32P)
Rarely, a treatment called radioactive phosphorus may be used. This might be when other treatments have been tried or are not suitable. You have it as an injection into a vein. It gives a dose of radiation to the bone marrow and reduces the number of blood cells being made. The effects of one treatment can last from months to years.
Having long-term treatment with radioactive phosphorus can increase the risk of leukaemia.
Allopurinol can be used to prevent gout. You may have it before another treatment, such as chemotherapy. If you have already had gout, your doctor may prescribe allopurinol that you take long term. This is to reduce the risk of you getting gout again.
You will need regular check-ups and blood tests. If you are worried or notice any new symptoms between appointments, tell your specialist doctor or nurse as soon as possible.
Making lifestyle changes to reduce your risk of complications can sometimes be challenging. You may find it easier to make changes as part of a group or with help from others. Tell your GP, practice nurse or haematology team if you are finding it difficult. There is lots of support available to help you live a healthier lifestyle.
Everyone has their own way of dealing with the different feelings they experience. You may find it helpful to talk things over with family and friends, or your specialist doctor or nurse.
Macmillan is also here to support you. If you would like to talk, you can:
- Call the Macmillan Support Line on 0808 808 00 00.
- Chat to our specialists online.
- Visit our Online Community to talk with people who have been affected by polycythaemia vera (PV), share your experience, and ask an expert your questions.
The organisations below also offer information and support:
Blood Cancer UK