• What is PV?
  PV is a blood disorder in which the bone marrow increases the red blood cell count.  When PV is diagnosed, your doctor must exclude any other causes of a raised red cell count, and may want to confirm the presence of a raised red cell mass (see tests).
  
  
• What causes PV?
  The cause of PV is unknown but most patients have a change in a molecule called JAK2 in their blood cells. Researchers are currently investigating the cause of this mutation. The chances of PV being inherited are slim. If another member of your family has a blood condition it is important to tell your doctor.
  
  
• What is the role of the red blood cell?
  Red blood cells contain haemoglobin, and their main function is to carry oxygen. Red blood cells have a special disc shape that allows them to bend and fit through the smallest of blood vessels, giving oxygen to the tissues.

The number of red cells you have depends on your age and gender. Men have more than women and newborn babies often have a higher number than adults.
 
Our bodies need iron, folic acid, and vitamin B12 to make red blood cells. A hormone produced in the kidney called erythropoetin increases red cell production. More erythropoetin is made if less oxygen reaches your kidneys.

• What's the problem if red blood cells go wrong?
  If there are too many red blood cells, then the disease is called a polycythaemia or erythrocytosis (polycythaemia is not to be confused with the disease called polycythaemia vera). The word erythrocytosis refers to too many red blood cells, but red blood cells could be elevated for a number of reasons, not necessarily denoting disease. When red cell counts increase, the blood becomes thicker, causing sluggish flow to organs and potentially causing blood clots. There are many symptoms that can be a feature of increased blood thickness. They include:
  
  
• A red complexion
• Headache
• Blurred vision or patchy loss of vision
• Confusion
• In extreme cases, stroke or coma

If you experience these symptoms it does not necessarily mean that you have the disease polycythaemia vera. There are many other causes for example of a red complexion!

• What is the average age of someone being diagnosed with PV?
  PV is a rare condition affecting mostly those who are middle aged or elderly, although more young people have been diagnosed in recent years.
  
  
• How is it diagnosed?
  The diagnosis of PV includes finding a high red cell count, which may be confirmed by the red cell mass test. Doctors most also exclude other causes of a high red cell number, for example heavy smoking. Haematologists making a diagnosis look for symptoms which can include:
  
  
• Redness of the face
• Headaches and visual problems
• Weight loss, fatigue and night sweats
• Breathlessness
• Bleeding
• Gout
• Itching
• A big spleen that causes a feeling of fullness in the stomach
  
  
• What are the tests to aid diagnosis?
  A variety of different tests may be needed. Most of these are simple blood tests including:

• Liver, glucose and kidney tests (done with a simple blood test)
• Iron, folate and vitamin B 12 measurements (simple blood test)
• Test for the JAK2 mutation (simple blood test)
• Measurement of oxygen levels in the blood. (by attaching a probe to the finger for approximately 2 mins)

Sometimes some special X-ray tests might be needed including:

• Chest x-ray and abdominal ultrasound.
• A red cell mass test - a sample of blood is taken in the Nuclear Medicine department and a very weak dye is added. The sample is returned to your blood, where it dilutes in your body. Another sample is taken later to see if there is a raised red cell number or too little water in the blood.

The results of these tests will usually show the cause of the raised red cell number. More specific tests may sometimes be required, such as:

• Lung function test (involves blowing into a tube and measuring what is exhaled)
• Blood test measuring haemoglobin binding to oxygen
• An ECG (echocardiogram) to measure the heart (involves sticking pads onto your chest and taking a reading of your heart waves. This test is painless and only lasts a couple of minutes.)
• Genetic testing of the erythropoietin receptor (a blood test)
• A sleep study
• A bone marrow test
  
  
• What is bone marrow?
  Bone marrow is a spongy substance that runs along the inside of your long bones and acts as a "factory" for making blood cells. By looking at a sample of marrow under the microscope, the haematologist will get a good picture of your blood-making mechanism.
  
  
• What is involved in a bone marrow test?
  Your doctor with usually take a sample of the bone marrow from the back of your pelvis bone. You will generally be asked to lie on your side with your legs curled up.

The area where the sample is to be taken will be cleaned and numbed by an injection of local anaesthetic - this can sometimes cause a stinging sensation which only lasts a few seconds. The doctor will insert a needle into the anaesthetised area.  You may feel a slight "pulling" sensation as the sample is taken.

For some people, a second sample called a trephine biopsy is required. This involves collecting a "core" of the bone. At this time you may feel an uncomfortable pushing sensation, but it will only last a few moments.

The whole procedure usually takes 20-30 minutes. The site will be covered with a small dressing and you will be asked to lie on your back for a few minutes.

The dressing needs to stay in place for 24 hours and it is best to avoid soaking in the bath during this time. You may experience slight discomfort in the area as the local anaesthetic wears off, which can be helped by taking a simple painkiller such as paracetamol.

• What are the possible complications of PV?
• Thickness of the blood
• Gout
• Itching
• Weight loss, fatigue, sweating.
• Bleeding
• Clotting
• Myelofibrosis
• Acute myeloid leukaemia
  
  
• What is the treatment for PV?
  The aim of treatment for PV is to control complications and reduce the number of red cells. This is achieved by venesection (see below) or by treatment with drugs to slow the production of red blood cells. The choice of treatment is individually tailored based on age, tolerance of venesection, platelet count and history of clotting or bleeding complications. The drugs commonly used to reduce red cell numbers or their stickiness include:
• Aspirin
• Hydroxycarbamide
• Interferon
• Anagrelide
• Busulphan
• Radioactive phosphorous
  
  
• What is a venesection?
  This simply means the removal of blood. Venesection uses the same technique as blood donation. A needle is put into the vein (in the arm) and roughly 450mls of blood is collected. The doctor will perform this procedure regularly until there is a satisfactory level of blood thickness (haematocrit). The target blood thickness depends on the disease, risk factors, tolerance of the procedure and any previous complications.
  
  
• What if I have PV and become pregnant?
  It is really important to discuss any plans of pregnancy with your haematologist, whether you are a man or woman. It seems unlikely that PV itself affects the ability to conceive, but some of the treatments we use can damage fertility, and if used in pregnancy, they can pose risks for the unborn baby. If anyone, whether a male or female is considering conceiving, they should not have taken hydroxycarbamide, busulphan, or phosphorous within three months prior to conception. Anagrelide is safe for use in males but pregnant women should not take it.

Women undergoing venesection are likely to go through pregnancy needing fewer venesections because of the dilution of blood that occurs in pregnancy. There is an increased thrombosis risk both during and soon after pregnancy. Your doctor is likely to prescribe aspirin throughout pregnancy and also suggest heparin, usually after your baby is born but sometimes during your pregnancy.

Males on some treatments need to be careful that their partner does not become pregnant.  Problems may occur, as hydroxycarbamide or busulphan can cause sperm damage. If you are taking hydroxycarbamide and want to make your partner pregnant, you will need to allow hydroxycarbamide to leave your system. You may need to switch to interferon at this time.

• What is the prognosis?         
  The prognosis depends on the complications, which may also affect the quality of life. Blood clots are common and can be serious. The chance of a clot occurring increases with age and previous clots. The aim of treatment is to reduce these complications and prolong life. In the absence of complications (especially myelofibrosis or acute myeloid leukaemia), people can expect a near-to-normal life span.
  

A number of people with PV may develop a complication of the disease known as myelofibrosis. People with myelofibrosis have low blood counts, large spleens and are at high risk of developing acute myeloid leukaemia. The onset of acute myeloid leukaemia is much less common and can have a less positive outlook. This can be discussed with your doctor.

If you'd like to read more detailed information about polycythaemia vera (PV), please go to the PV main page