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Polycythaemia vera (PV)

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Polycythaemia vera (PV) symptoms and diagnosis

You may not have any symptoms at all before or when you’re diagnosed. That’s why many people with PV are diagnosed following a routine blood test.

The increase in red blood cells makes it hard for blood to flow smoothly through your blood vessels. This is known as hyperviscosity and may mean you get some of these symptoms:

  • headaches
  • confusion
  • blurred vision
  • skin reddening (plethora)
  • itchy skin (pruritus).

A less common complication of PV is gout, which can cause inflammation of the joints.

Thrombosis (blood clots)

People with PV are at an increased risk of thrombosis (blood clots). Thrombosis is a serious condition and may occur in the blood vessels of your:

  • brain (causing a stroke or mini-stroke/TIA – transient ischaemic attack)
  • eyes (causing blurred vision or loss of vision)
  • heart (causing a heart attack).

Blood clots can also form in the veins of your legs. This is known as deep vein thrombosis or DVT. Clots can also form in the vessels in your abdomen (stomach area). If a clot dislodges and travels to the lung, it may cause a pulmonary embolism (or PE). This usually results in low oxygen levels, sharp chest pain and shortness of breath. In some cases this may be fatal. The risk of clots is highest if the PV isn’t treated.

You’ll have regular blood tests so your healthcare team can monitor your condition and spot any early signs of a blood clot.

Get urgent medical help if you have any of these symptoms:

  • sudden chest pain or shortness of breath
  • swelling and/or pain in your calf on one side
  • slurred or abnormal speech, weakness in your arms or legs, or drooping on one side of your face
  • swelling in your abdomen or jaundice (your skin turning a yellow colour)
  • sudden loss of vision in one eye.

Tests to diagnose PV

Most people are suspected of having PV after a routine blood test or by going to their GP with symptoms. You’d then have a set of tests to confirm the exact diagnosis of PV.

Polycythaemia (rather than polycythaemia vera) is defined as a persistent increase in the proportion of your blood that’s made up of red blood cells. Your doctor may refer to this as your ‘packed cell volume’ (or PCV). This is usually checked using a test called a full blood count.

For this test a small sample of your blood will be taken, then the cells will be studied under a microscope in a laboratory.

Some people need tests on their bone marrow done before their doctors can make a diagnosis. Before these tests can be carried out, doctors will need to take a bone marrow sample (biopsy). This helps to rule out any other bone marrow problems.

The result of these tests alone aren’t enough for your doctor to diagnose PV, as there are a number of other reasons and conditions that can mean you have too many red blood cells.

These include:

  • smoking,
  • lung diseases,
  • sleep apnoea (where your normal breathing is disrupted while you’re asleep),
  • living at high altitudes,
  • some kinds of tumours,
  • anabolic steroids (prescription performance-enhancing drugs),
  • testosterone treatment, and
  • some rare inherited genetic disorders

Find out more about bone marrow biopsies.

The discovery of the JAK2 genetic fault in 2005 has made it easier to diagnose PV. Some of your DNA will be taken from a sample of your blood, and tested. If you have this genetic fault, doctors will be able to confirm you have PV.

Further tests

If there’s no clear cause for your polycythaemia and you don’t have the JAK2 genetic fault, your doctor will do more tests to confirm a diagnosis.

These may include:

  • further blood tests for erythropoietin (a hormone that increases red blood cell production) levels and other genetic tests,
  • red cell mass studies (using radioisotopes) to distinguish ‘apparent’ polycythaemia from actual polycythaemia,
  • tests on blood samples taken from an artery (instead of vein) to measure your oxygen levels,
  • tests on samples of your bone marrow,
  • lung function tests, and
  • scans to see if your spleen is swollen or other possible causes – for example, a tumour which is releasing erythropoietin

Your doctor will be able to talk to you about any of these tests and explain how they’re done and what they’re looking for. Be sure to ask them any questions about these tests if you’re unsure.

Worried about anything or have questions?

If you have any questions, worries, or just need someone to talk to, please don't hesitate to contact our Support Services Team via phone or email.

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