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This information is about essential thrombocythaemia (ET), also known as primary thrombocythaemia. This is one of a group of conditions known as the chronic myeloproliferative diseases (CMPDs).
The myeloproliferative diseases are a group of conditions affecting the function of the bone marrow. They involve an over-production of one or more of the blood cells that are produced in the bone marrow.
The main types of chronic myeloproliferative disease are:
These conditions usually develop very slowly and, as most people who are affected are older, it usually doesn't affect their normal life span.
Some people may eventually develop more progressive forms of the chronic myeloproliferative diseases (CMPDs), such as myelofibrosis. This is a condition in which the bone marrow is replaced by fibrous (scar) tissue. Rarely people with CMPDs will develop leukaemia.
The bone marrow is the spongy material in the centre of some of our bones. It produces cells known as stem cells. Stem cells are immature cells that develop into three different types of blood cells:
Essential thrombocythaemia (ET) is a chronic myeloproliferative disease affecting the cells in the bone marrow that produce platelets.
ET is a rare condition that can affect people at any age, including children, but it's rare in anyone under 50.
Some people have a change (mutation) in a gene|, called the JAK2 gene, that may have caused their condition. This gene produces an important protein involved in blood production. Finding this faulty gene can help to make the diagnosis.
Having too many platelets in the blood may not cause any symptoms and some people are diagnosed with ET during a routine blood test, when they have no symptoms.
A high number of platelets can cause the blood to clot more easily. It may also cause abnormal bleeding, because the platelets are immature and cannot function properly.
Symptoms can occur because a blood clot (thrombosis) has formed in a vein in the body. Clotting problems are more common in people over 60, or those who have already had a previous blood clot or with conditions such as high blood pressure or diabetes. The symptoms will depend upon where in the body a clot forms. Common sites for a clot to form are:
Problems caused by abnormal bleeding are less common than clotting problems. They can include:
If you develop any of these symptoms in between check-ups, you should discuss them with your doctor or haematologist (a specialist in blood disorders).
ET is usually diagnosed by a haematologist. The diagnosis may be suspected after the results of a simple blood test called a full blood count. This counts the number of red cells, white cells, and platelets. In ET there will be a high platelet count.
You may have a blood test to check for a change (mutation) in the JAK2 gene.
Other conditions can cause the platelet count to be increased, such as infection, arthritis, chronic bleeding, or a lack of iron in the blood. These need to be ruled out before a diagnosis of essential thrombocythaemia can be made.
This involves taking a sample of bone marrow from the back of the hipbone (pelvis). The sample is then examined under a microscope to see if it contains any abnormal cells.
The bone marrow sample is taken under a local anaesthetic. You are given an injection to numb the area, and a needle is passed gently through the skin and into the bone. A tiny sample of the marrow is then drawn (aspirated) into a syringe.
Sometimes a small core of marrow is also needed. This takes a few minutes longer. This procedure can be painful for a few seconds, and you may feel some discomfort for a few hours afterwards. You may need to take some mild painkillers, such as paracetamol.
The aim of treatment is to control the number of platelets and so reduce the risk of abnormal clotting or bleeding (and the associated complications). If treatment is successful, the outlook for someone with ET can be very similar to that of someone of the same age who doesn’t have the condition.
If you have been diagnosed with an ET which is not causing any problems, you may not need any treatment for a while. You will be seen by your doctor who will monitor your condition with regular blood tests.
Aspirin is often used as it can affect the way the platelets ‘stick’ together, which can help to reduce the risk of clotting. However, aspirin will not reduce the platelet count. Side effects of aspirin include an increased risk of bleeding, and ulcers in the stomach. You will be advised to use other simple painkillers, like paracetamol, should you need them.
Chemotherapy| is the use of anti-cancer (cytotoxic) drugs to destroy cancer cells. It may be given to try to reduce the platelet count.
The main drug used is hydroxycarbamide|, which is given as a tablet. It can cause side effects, although generally these will be mild. Side effects can include lowered resistance to infection|, diarrhoea|, anaemia, feeling sick| (nausea), mouth ulcers| and leg sores or ulcers.
Hydroxycarbamide may also affect fertility|. People taking it are advised not to get pregnant or father a child, as there may be a risk of harming the developing foetus. It's advisable to use effective contraception while taking the drug and also for a few months afterwards.
If hydroxycarbamide is used in combination with other chemotherapy drugs over a long period of time it may increase the chance of the ET developing into a leukaemia.
The chemotherapy drug busulphan| may also be used. Busulphan is usually given as a tablet but can be given as an injection into a vein. It can cause similar side effects to hydroxycarbamide.
Interferon| is a protein that occurs naturally in the body. It can also be made as a drug. It is given to stimulate the body’s defence system, and can help to slow down the production of platelets. Interferon is given as an injection under the skin, usually three times a week. Side effects include flu-like symptoms, dizziness, and extreme tiredness (fatigue)|.
Anagrelide is a drug that reduces the number of platelets in the blood. It's given as a capsule. Side effects can include headaches and palpitations (sensation of a fast heartbeat).
It doesn't seem to affect fertility but anagrelide should never be taken during pregnancy or if you are thinking of getting pregnant. It's important to use effective contraception when taking anagrelide.
Anagrelide is usually given when other treatments have already been tried. Some studies suggest that anagrelide may increase the chances of developing myelofibrosis.
Radioactive phosphorus may be used to treat ET. It is given as an injection into a vein. It irradiates the bone marrow and can lower the number of platelets being produced. The effects of a single injection can last months to years. Treatment with radioactive phosphorus over many years can cause an increased risk of leukaemia. Your doctor or nurse will explain your treatment to you and will answer any questions that you have.
Research into new ways of treating essential thrombocythaemia is ongoing. Doctors use clinical trials| to assess new treatments. You may be asked to take part in a clinical trial.
Before any trial is allowed to take place it must be approved by a research ethics committee, which protects the interests of those taking part. Before you enter a trial, your doctor or research nurse must discuss the treatment with you so that you have a full understanding of the trial and what it involves. You may decide not to take part, or to withdraw from the trial at any stage. You will then receive the best standard treatment available.
Your treatment may continue for a number of years, and you will need to have regular check-ups and blood tests. These will probably be ongoing. If you have any problems, or notice any new symptoms in between these times, let your nurse or doctor know as soon as possible.
Everyone has their own way of dealing with their condition and the different emotions| they experience. Some people find it helpful to talk things over with family and friends or their doctor or nurse. You can also contact our cancer support specialists| for more information and support.
This section has been compiled using information from a number of reliable sources including:
For further references, please see the general bibliography|.
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