Polycythaemia

When to seek immediate medical advice

Polycythaemia can cause blood clots. These put you at risk of life-threatening problems such as:

• pulmonary embolisms – a blockage in the blood vessel that carries blood from the heart to the lungs
• deep vein thrombosis (DVT) – a blockage that forms in the blood vessels in your leg before moving elsewhere in your body

Seek medical help immediately if you or someone you're with shows signs of DVT or a pulmonary embolism. These include:

• pain, swelling, redness and tenderness in one of your legs
• a heavy ache in the affected area
• warm skin in the area of the clot
• breathlessness
• chest or upper back pain
• coughing up blood
• feeling lightheaded or dizzy
• fainting

Polycythaemia also increases your risk of heart attack and stroke. Seek emergency medical help if you think that you or someone you're with is having a heart attack or stroke.

How polycythaemia is diagnosed

Polycythaemia can be diagnosed by carrying out a blood test to check:

• the number of red blood cells in your blood (red blood cell count)
• the amount of space the red blood cells take up in the blood (haematocrit level)

A high concentration of red blood cells suggests you have polycythaemia.

Polycythaemia is sometimes only discovered during a routine blood test for another reason.

Your GP may refer you to a haematologist (a specialist in blood disorders) for more tests, to confirm the diagnosis and to determine the underlying cause.

These may include:

• a blood test to look for the changed JAK2 gene
• an ultrasound scan of your tummy to look for problems in your kidneys

Outlook for polycythaemia

The outlook for polycythaemia largely depends on the underlying cause.

Many cases are mild and may not lead to any further complications. However, some cases – particularly cases of PV – can be more serious and require long-term treatment.

If well controlled, polycythaemia should not affect your life expectancy, and you should be able to live a normal life. However, people with PV can have a slightly lower life expectancy than normal due to the increased risk of problems, such as heart attacks and strokes.

PV can also sometimes cause scarring of the bone marrow (myelofibrosis), which can eventually lead to you having too few blood cells. In some rare cases, it can develop into a type of cancer called acute myeloid leukaemia (AML).