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HealthInfo Canterbury

Primary polycythaemia (high red blood cells)

Your blood is made of white blood cells, red blood cells, platelets, and plasma

Primary polycythaemia, also called primary polycythaemia vera or PV, is caused by your bone marrow making too many red blood cells. Most people with polycythaemia remain well, but they do have a higher risk of getting blood clots. These can lead to deep vein thrombosis (DVT), pulmonary embolism, strokes, or heart attacks.

Sometimes, after many years people with polycythaemia can develop other blood problems, such as anaemia, scarring of their bone marrow (a condition called myelofibrosis), or even leukaemia.

Primary polycythaemia is diagnosed with a blood test. You may also need a bone marrow biopsy.

Treatment to lower your red blood cells to the normal level reduces your risk of blood clots. This is either done by regularly removing blood (called blood letting or venesection) or with medication.

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Written by Haematology Department, Christchurch Hospital. Adapted by HealthInfo clinical advisers. Endorsed by clinical director, Haematology, Canterbury DHB. Last reviewed May 2020.

See also:

Understanding your complete blood count results

Page reference: 31421

Review key: HIPPO-31421