Browser does not support script.
Skip to main content
search here
Macmillan and Cancerbackup merged in 2008. Together we provide free, high quality information for people affected by cancer through our publications, website and phone service. Find out more|.
Find out how we produce our information|
This information is about polycythaemia vera (PV), which is one of a group of conditions known as the chronic myeloproliferative diseases (CMPDs).
The chronic myeloproliferative diseases (CMPDs) are a group of conditions that affect the function of the bone marrow. They involve an overproduction of one or more of the types of blood cells that are produced there.
The main types of CMPD are:
These conditions usually develop very slowly. And as most people who are affected are older, it usually doesn't affect their normal life span.
Some people may eventually develop more aggressive forms of the CMPDs such as myelofibrosis. This is a condition in which the bone marrow is replaced by fibrous (scar) tissue. Rarely, people with CMPDs will develop leukaemia|.
The bone marrow| is the spongy material in the centre of some of our bones. It produces cells known as stem cells. Stem cells are early blood cells that develop into three different types of blood cells:
PV is a myeloproliferative disorder in which too many red blood cells are made by the bone marrow.
Like other myeloproliferative diseases, PV is a rare condition and mainly affects people over the age of 40.
Some people have a change (mutation) in a gene| called the JAK2 gene that may have caused their condition. This gene produces an important protein involved in blood production. The fault in the gene occurs during the person's lifetime. It isn't inherited and can't be passed on to any children. Finding this faulty gene can help make the diagnosis.
In some people, the bone marrow makes more red blood cells than normal as a result of a condition somewhere else in their body, such as lung disease and some kidney disorders. This is called secondary polycythaemia. The treatment of this type of polycythaemia is very different from PV and usually involves treating the underlying condition.
Having a high number of red blood cells in the blood doesn't always cause symptoms. Usually, some people are diagnosed with PV after a blood test is taken for another reason.
Too many red blood cells can make the blood much thicker than normal. If you have too many red blood cells your haemoglobin (Hb) level will be raised. Some people with PV also have increased numbers of white blood cells and platelets in their blood.
This is caused by a high number of red blood cells in the blood making it thicker than normal and affecting the way it flows. Symptoms of hyperviscosity include headaches, blurred vision, breathlessness|, and confusion. Some people may also notice their skin appears redder than usual.
Other symptoms can include sweating and itching, especially after a bath or shower.
A small number of people with PV may develop gout, a condition caused by the breakdown of a high number of red blood cells. It causes inflammation and pain in the joints, usually of the big toe and less often in the ankles, hands or knees.
A high level of red blood cells or platelets may cause the blood to clot. Clots can form anywhere in the body and the symptoms will depend on which part of the body is affected.
Common sites for a clot to form are:
This can cause symptoms such as pain, swelling, heat, and redness in the calf (known as deep vein thrombosis or DVT).
This may cause mild symptoms such as headaches, sight disturbances, or dizziness. Blood clots in the brain may also cause symptoms that are more serious, such as a stroke or TIAs (transient ischaemic attacks [mini-strokes]).
A blood clot in the heart may cause chest pain, and in severe cases, can result in a heart attack.
A blood clot in the lung may cause breathlessness and chest pain. This is known as pulmonary embolism.
As well as causing clotting problems PV very occasionally causes abnormal bleeding. This can cause symptoms such as:
If you develop any of these symptoms between your appointments, tell your haematologist (specialist in blood disorders).
PV is usually diagnosed by a haematologist. The diagnosis may be suspected following a blood test called a full blood count. This counts the number of the red blood cells, white blood cells and platelets. In PV, there is a high red blood cell count.
You will have a blood test taken to check if you have a change (or mutation) in the JAK2 gene.
Other conditions can cause an increased red blood cell count. These need to be ruled out before a diagnosis of PV can be made.
The tests and investigations that may be done to confirm a diagnosis of PV are:
This involves taking a sample of bone marrow from the back of the hip bone (pelvis). The sample is then looked at under a microscope to see if it contains any abnormal cells.
The bone marrow sample is taken under a local anaesthetic. You are given a small injection to numb the area, and a needle is passed through the skin and into the bone. A sample of the liquid marrow is then drawn (aspirated) into a syringe (a bone-marrow aspirate).
Sometimes a small core of marrow is also needed (a trephine biopsy) and this takes a few minutes longer.
You may feel some discomfort for a few days after a bone marrow biopsy, which can usually be relieved with painkillers such as paracetamol.
A bone marrow sample being taken
View a large copy of the bone marrow sample being taken image|
Other tests and investigations may also be needed to confirm that the high levels of red blood cells are caused by PV, and not some other condition. These might include:
Your spleen may be enlarged, as it is involved in the breakdown of red blood cells.
This tests whether the increased concentration of red blood cells in your blood is caused by an increase in the number of red blood cells (a sign of PV), or by a reduction in the amount of plasma (the liquid part of blood).
A sample of your blood is mixed with a mildly radioactive dye and injected into a vein in your arm. It then circulates around your body. A short time later a second sample of blood is taken, and the doctors are able to determine the total mass of your red blood cells.
The plasma the blood cells are suspended in is also measured. By comparing the two results, the doctors can tell if you have an increased number of red blood cells in your blood or a reduced amount of plasma. Both of these would increase the concentration of the blood, but for a diagnosis of PV there needs to be an increased number of red blood cells only.
The aim of treatment is to reduce the number of red blood cells in the blood, and therefore reduce the risk of any complications occurring. Treatment will depend on how many red blood cells you have, your age, whether you have symptoms caused by the disease and whether you have a high platelet count. Often treatment is individually planned. If you have been diagnosed with PV, but it is 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. It involves removing some of your blood.
A needle attached to tubing and a bag is inserted into your vein. The blood flows through the needle and tubing into the bag. The procedure is similar to that used for blood donors. Usually, about a pint of blood is removed at a time. This procedure can be repeated if necessary.
Venesection can help reduce the number of red blood cells you make, but it doesn't affect the number of platelets in your blood. It works by reducing the amount of iron in your body. Iron is needed to make red blood cells. You shouldn't take any supplements containing iron, unless told to do so by your doctor. Each time some blood is removed, you will be asked to drink plenty of fluids to replace what you have lost.
This can help prevent clots because it affects the way platelets 'stick together'. Some people may be prescribed it as part of their treatment. One of the side effects of aspirin is an increased risk of bleeding and ulcers in the stomach. You will be advised to use other simple painkillers, like paracetamol, if you need them.
Chemotherapy| is the use of cytotoxic (cell-killing) drugs. It is most commonly used to treat cancers, but it is sometimes used to treat other conditions. Hydroxycarbamide| (which used to be called Hydroxyurea) is a chemotherapy tablet that can help reduce the blood cell count. It can cause side effects, but generally these are mild. Side effects can include lowered resistance to infection|, diarrhoea|, anaemia, feeling sick (nausea)|, mouth ulcers, and leg sores or ulcers. You may find our section on mouth care during chemotherapy| helpful.
Hydroxycarbamide may also affect fertility|. People taking it are advised not to get pregnant or father a child, as there may be a risk of harming the developing baby. It is advisable to use effective contraception while taking the drug and also for a few months afterwards.
If hydroxycarbamide is used over a long period of time in combination with other chemotherapy drugs|, it may increase the chance of the PV developing into a leukaemia|.
The chemotherapy drug busulphan| may also be used. However this drug is used less often than hydroxycarbamide. Busulphan is usually given as a tablet, but can be given as an injection into a vein. Its side effects are similar to those of hydroxycarbamide.
Interferon| is a natural substance made by the body. It is also made as a drug. It works by stimulating the immune system (body's defence system). Interferon is given as an injection under the skin, usually three times a week. Side effects include flu-like symptoms, dizziness and extreme tiredness (fatigue)|.
This may be used in some situations. Radioactive phosphorus is given as an injection. It irradiates the bone marrow and can lower the number of platelets being produced. The effects of a single injection can last from months to years.
Treatment with radioactive phosphorus over many years can cause an increased risk of leukaemia.
Allopurinol is used to treat gout that some people with PV have. Inflammation of the joints can often be successfully treated with painkillers.
Rarely, this intensive treatment is used for younger people with PV that is developing into myelofibrosis. It involves replacing stem cells (early blood cells) that have been destroyed by high doses of chemotherapy. After the treatment, 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.
Research into new ways of treating PV is ongoing. Your doctor may invite you to take part in a clinical trial| to compare a new treatment against the best available standard treatment.
Your doctor must discuss the treatment with you, and have your informed consent before entering you into a trial.
Before any trial is allowed to take place, it must be approved by a research ethics committee, which protects the interests of those taking part.
You may decide not to take part or to withdraw from the trial at any stage. You will then receive the best standard treatment available.
You will need to have regular check-ups and blood tests. These will probably be ongoing. If you have any problems, or notice any new symptoms in between these times, let your nurse or doctor know as soon as possible.
Everyone has their own way of dealing with their condition and the different emotions| they experience. Some people find it helpful to talk things over with family and friends or their doctor or nurse. You can also contact our cancer information nurse specialists| or the organisations below for more information and support.
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 section has been compiled using information from a number of reliable sources, including:
For answers, support or just a chat, call the Macmillan Support Line free (Monday to Friday, 9am-8pm)
If you have any questions about cancer, need support or just want someone to talk to, ask Macmillan.