Polycythaemia vera (PV)
Polycythaemia vera (PV) is one of a group of conditions known as myeloproliferative disorders (MPDs). These disorders affect how the bone marrow works.
The main types of MPD are:
Bone marrow is part of the immune system, which protects us from infection and disease. The marrow is in the spongy material found inside bones. This is where stem cells are made. Stem cells are blood cells at their earliest stage of development. All blood cells grow from stem cells. The three main types of blood cells are:
red blood cells, which carry oxygen around the body
white blood cells, which fight infections
platelets, which help blood clot to stop bleeding.
The bone marrow makes millions of blood cells every day. In MPDs, the bone marrow makes too many blood cells.
Polycythaemia vera (PV)
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PV is a rare condition that mainly affects people over the age of 40. It is twice as common in men as in women. PV develops very slowly and, for most people, it doesn't affect their normal life span. Rarely, people with polycythaemia vera develop myelofibrosis or leukaemia.
PV causes changes in the bone marrow. This can lead to too many red blood cells being made, which makes the blood thicker than normal. Some people with PV also have increased numbers of white blood cells and platelets in their blood.
Having too many red blood cells in the blood isn’t always due to changes in the bone marrow. Some conditions such as lung disease or a kidney disorder can lead to an increase. This is called secondary polycythaemia. Secondary polycythaemia can also be caused by smoking, drinking large amounts of alcohol or having high blood pressure. The treatment of secondary polycythaemia is different from PV. It involves changing the habits or treating the condition that has led to the increased number of blood cells.
Having a high number of red blood cells doesn't always cause symptoms. Some people are diagnosed with PV following a blood test taken for other reasons.
Possible symptoms of PV include:
red skin, for example, on the face, hands and feet.
Sometimes other symptoms develop such as gout (inflammation in the joints) or blood clots. This is due to complications that PV can cause.
Bleeding or bruising
Very occasionally, PV can cause abnormal bleeding. This can cause symptoms such as:
abnormal vaginal bleeding in women
The spleen sits on the left side of the tummy (abdomen) just under the ribs and is normally about the size of a fist. It helps break down red blood cells. PV can cause the spleen to grow bigger than normal. Symptoms of an enlarged spleen include discomfort on the left side of the tummy and quickly feeling full when eating.
PV is usually diagnosed by a haematologist (a specialist in blood disorders). The diagnosis may be suspected from the results of a routine blood test called a full blood count. This test counts the number of red blood cells, white blood cells and platelets in the blood.
Various tests and investigations may be done to confirm a diagnosis of PV. These tests will check to see if other conditions are affecting your blood counts. This may result in a diagnosis of secondary polycythaemia.
JAK2 blood test
This blood test checks for a change (mutation) in a gene called JAK2. This gene helps control how many blood cells are made. A change in the gene can cause PV. About 95 out of 100 people with PV (95%) have a mutation in the JAK2 gene. The mutation happens during the person's lifetime. It isn't something you’re born with and you can’t pass it on to your children.
Other tests that may be done include a:
A check of the levels of iron and vitamin B12 in the blood.
A blood test to check if your body is making too much erythropoietin (a hormone that encourages red blood cells to be made).
A test to check how much oxygen your blood is carrying (oxygen saturation test).
A chest x-ray to look at the lungs, heart and arteries.
An ultrasound scan of the tummy area (abdomen) to look at the kidneys, liver and spleen.
A bone marrow biopsy to look for abnormal cells in the bone marrow. In this test, the doctor numbs the area over the back of your hip bone (pelvis) and then takes a sample of bone marrow from the hip bone. The sample is sent to a laboratory to be examined under a microscope.
A red cell mass study to look at the concentration of red blood cells in the blood. This test is less common.
All of these tests can be done as an outpatient.
Treatment for PV aims to reduce the number of red blood cells in the blood. This will reduce symptoms and the risk of complications. Your treatment will depend on your full blood count, your fitness level and if you have symptoms caused by the disease. If you have been diagnosed with PV but it’s not causing you any problems, you may not need any treatment for a while.
This is one of the simplest ways to reduce the number of red blood cells in your blood and make your blood thinner. It involves taking about a pint of blood from you.
A doctor or nurse puts a needle attached to tubing and a bag into your vein. Blood flows through the needle and tubing into the bag. When enough blood has been taken, the needle is taken out.
Venesection may be done regularly, every few weeks or months, until your blood gets to the right level of thickness. Each time some blood is removed, you will be asked to drink plenty of fluids to replace what has been removed.
Having a high level of red blood cells or platelets in the blood increases the chance of blood clots (thromboses). Aspirin can help prevent clots because it affects the way platelets 'stick together'. 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. If you need to take a painkiller while you’re taking aspirin to prevent blood clots, ask your doctor for advice. Some types of painkillers, such as ibuprofen, may not be suitable.
Chemotherapy is the use of anti-cancer (cytotoxic) drugs to destroy cancer cells. Chemotherapy can also be used to treat non-cancerous conditions. It can be used to reduce the blood cell count in PV.
Hydroxycarbamide is the most commonly used chemotherapy drug to treat PV. It is taken as a tablet. It can cause side effects, but generally these are mild. Side effects may include lowered resistance to infection, diarrhoea or constipation. There is a very small risk of leukaemia developing if hydroxycarbamide is used for a long time. Patients under the age of 40 with PV may be given other drugs instead.
Rarely, the chemotherapy drug busulphan may be used. This drug is used when other treatments have not been successful. Busulphan is usually given as a tablet. Its side effects are similar to those of hydroxycarbamide. There is also a risk of leukaemia developing if busulphan is used for a long time.
Chemotherapy may affect fertility. People taking chemotherapy drugs are advised not to get pregnant or father a child. This is because there may be a risk of harming the developing baby. It is advisable to use contraception while taking chemotherapy drugs and for a few months afterwards.
Interferon is a natural substance made by the body. It is also made as a medicine. It can be used to reduce the rate at which blood cells are made. Interferon is given as an injection under the skin. Side effects can include flu-like symptoms, headaches, dizziness, tiredness and mood swings.
Radioactive phosphorus (32P)
Rarely, a treatment called radioactive phosphorus may be used. It is given as an injection. It irradiates the bone marrow and can lower the number of blood cells being produced. The effects of a single injection can last from months to years.
Long-term treatment with radioactive phosphorus can cause an increased risk of leukaemia.
Some people with PV develop gout. Gout is a painful condition that is caused by inflammation in joints such as the big toe and sometimes in the ankles, hands or knees.
Allopurinol can be used to prevent gout. It may be given before treatment that destroys blood cells, such as chemotherapy. If you have had gout, you may be prescribed allopurinol to take for the long term to prevent it happening again.
Stem cell or bone marrow transplant (from a donor)
Rarely, this intensive treatment is used for younger people with PV that’s developing into myelofibrosis. It involves giving high doses of chemotherapy and then replacing stem cells (early blood cells) that have been destroyed by the treatment. After chemotherapy, you are given stem cells from a donor who can be a brother, sister or a volunteer who is a match for you.
Your doctor or nurse will explain your treatment to you and should answer any questions that you have.
There are also some newer treatments available that may be used to help control PV.
You may be invited to join a clinical trial looking at new ways of treating PV. You can talk about this with your haematologist.
You’ll have regular check-ups and blood tests. If you notice any new symptoms in between appointments, you should discuss them with your doctor or haematologist as soon as possible. Symptoms to be aware of are pain or swelling in the leg, breathlessness, chest pain or severe headaches. These could be signs of a blood clot.
In addition to the treatments and check-ups recommended by your haematologist, you may want to look at ways of staying healthy. Following a healthy diet, drinking plenty of fluids, staying active and giving up smoking are good for your general health. This may also help reduce the risk of complications such as blood clots. Your doctor or specialist nurse can give you advice about this.
You may have many different emotions including anger, resentment, guilt, anxiety and fear. These are all normal reactions and are part of the process many people go through in trying to accept and manage their condition.
Everyone has their own way of coping with difficult situations. Some people find it helpful to talk to family or friends, while others prefer to seek help from people outside their situation. Some people prefer to keep their feelings to themselves. There is no right or wrong way to cope, but help is there if you need it. Our cancer support specialists can give you information about counselling in your area.
MPD Voice is a support network for people with MPDs (myeloproliferative disorders) providing information and support.
Leukaemia CARE is a national group promoting the welfare of people with leukaemia and other blood disorders. It has regional support groups in many counties.
This information has been compiled using information from a number of reliable sources, including:
Amendment to the guideline for diagnosis and investigation of polycythaemia/erythrocytosis. British Journal of Haematology. 2007. 138: 812–823.
Guidelines for the diagnosis, investigation and management of polycythaemia/erythrocytosis. British Journal of Haematology. 2005. 130: 174–195.
Ansell SM. Rare Haematological Malignancies. 2008. Springer.
With thanks to: Dr Tim Somervaille, Honorary Consultant in Haematology, The Christie NHS Foundation Trust, Manchester; and the people affected by cancer who reviewed this edition.
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