Essential Thrombocythaemia

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 researched.

How is ET diagnosed?

The following tests or examinations may be used to diagnose or manage the condition:

  • 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. Treatments include:

  • Anti-platelet therapy which reduces the ability of platelets to clump together
  • Platelet-lowering therapy which reduces the number of platelets in the blood

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