What is essential thrombocythaemia (ET)?
Essential thrombocythaemia is a condition where there are too many platelets
in the blood. In ET the platelet levels are
> 600x109/L whilst normal platelet levels are in the range 150 –
400x109/L or 150 - 400 billion platelets per litre of blood.
Platelets circulate in your blood, and help the blood to clot. When there
are too many platelets in your blood, your blood can become ‘sticky’ and you
may be at increased risk of suffering from blood clots where you don’t need
them, or from excess bleeding.
Platelets are tiny fragments of megakaryocytes that are cells made in the
bone marrow. People with ET have an increased number of megakaryocytes which
make platelets that are released into the blood.
What are the signs and symptoms of ET?
It is common not to have any symptoms from ET, however in some patients high
platelet counts may cause blood clots in blood vessels and can cause strokes
and heart attacks.
Other patients may experience reduced clotting which may result in increased
bleeding for example nose bleeds.
Who is likely to be at risk of ET?
Each year 24 per 100,000 people are diagnosed with ET.
In older patients, men are as likely to get ET as women are. However, in younger
patients, the disease occurs more often in women.
Unfortunately, nobody knows why people with ET make too many megakaryocytes.
There may be a genetic cause in some patients, but this is still being
How is ET diagnosed?
The following tests or examinations may be used to diagnose or manage the
- Full blood count (blood test)
- Chest x-ray
- Ultrasound scan
- Bone marrow biopsy
What are the treatments for ET?
The main aim of treatment of ET is to prevent clotting and bleeding events.
- Anti-platelet therapy which reduces the ability of platelets to clump
- Platelet-lowering therapy which reduces the number of platelets in the blood
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