What is polycythaemia vera?
Polycythaemia vera (PV) is a rare condition where the body makes too many red blood cells. The extra red blood cells in the circulation make the blood ‘thicker’ and slow down the flow of blood, reducing oxygen supply to parts of the body.
Some people with PV also make too many of the other components of blood – platelets and white blood cells.
Symptoms of polycythaemia vera
In the early stages of polycythaemia vera there may be no symptoms. Often the disease is diagnosed after a routine blood test.
As the disease progresses, symptoms may include:
- itchy skin, especially after a hot shower;
- tingling or burning feeling in the hands and feet;
- tinnitus (ringing in the ears);
- chest pain;
- abdominal discomfort due to an enlarged spleen;
- shortness of breath (often when lying down); and
- blurred vision.
Some people with PV have a very distinctive appearance. Their face may have a marked reddish-blue colour (plethora). This is particularly obvious on the lips, cheeks, ears and tip of the nose. The hands and feet may have a similar coloration.
Bruising and a tendency to bleed are also common.
The cause of polycythaemia vera is not fully understood but it is known that most people with polycythaemia vera have a genetic mutation — called JAK2 — that affects a protein in bone marrow cells, causing them to produce too many red blood cells.
It’s not clear what causes this mutation, but it is not an inherited problem, so it’s not passed from parents to children.
Polycythaemia vera affects men slightly more than women, and is most common in those older than 60 years.
In people with PV, a blood test called a full blood count generally shows an increased number of red blood cells and elevated haemoglobin (the protein in red blood cells that carries oxygen). Sometimes there are also increased numbers of platelets and white blood cells.
Blood tests may also reveal low levels of erythropoietin – the hormone that stimulates the production of red blood cells.
A bone marrow aspiration or biopsy can be done to look for evidence of PV in the bone marrow. A sample of bone marrow can be taken from the hip bone using a long, thin needle. This test is usually performed using local anaesthetic.
Tests can also be performed on blood and bone marrow cells to look for the JAK2 gene mutation.
The most significant complication of PV is thrombosis (blood clots). Blood clots can cause a variety of serious problems, including stroke, heart attack and pulmonary embolism (blood clots in the lungs).
The increased number of red blood cells can also cause gout; kidney stones; and ulcers in the stomach, oesophagus (gullet) and small intestine.
Some people with PV develop a condition called myelofibrosis, where the bone marrow is replaced with scar tissue. A small number of people with PV develop leukaemia (cancer of the bone marrow).
Treatment of polycythaemia vera
There is no cure for PV, but there are treatments available to keep the condition under control. The treatment depends on the severity of the condition and the symptoms and complications experienced.
Reducing red blood cells
Venesection, or removing blood in the same way as for blood donation, is the main treatment for PV. Venesection (sometimes called phlebotomy) reduces the volume of red blood cells, thereby improving the thickness of the blood. Venesection may initially need to be done weekly, but once the red blood cell numbers are close to normal, every few months.
Medicines can also be used to reduce the number of red blood cells. Hydroxyurea is a medicine that can suppress the production of red blood cells in the bone marrow. Immunotherapy medicines such as interferon alpha can help your body fight bone marrow cells that are overproducing red blood cells.
Radiation treatment can also suppress overactive bone marrow cells.
Treating symptoms and complications
Low-dose aspirin may be recommended to reduce your risk of blood clots and relieve burning pain in the hands and feet.
Itchy skin can be treated with medicines and ultraviolet light therapy. It’s also a good idea to bathe in cool water, pat your skin dry and use moisturiser on your skin.