ET is a disorder which causes the body to produce too many platelets.
Patients with essential thrombocythaemia (ET) have an elevated platelet count – their blood contains too many platelets. The high number of platelets causes blood to be ‘sticky’, so people with ET are a higher risk of both clotting. People with ET can also have bleeding problems because their platelets do not always work well. However, some people with ET don’t experience any symptoms at all.
People generally develop ET as adults. Most people who develop ET are diagnosed at age sixty or older, but it appears that the disorder is becoming more common in younger people, especially women under forty.
Recent research has shown that about 50% of patients have a mutation (or change) in a protein called JAK2. Another 2-5% of patients have a mutation in a protein called MPL. Both JAK2 and MPL are proteins which regulate blood cell production. Researchers don’t currently understand what causes these mutations to occur.
Essential thrombocythaemia (ET) is sometimes called essential thrombocytosis or primary thrombocytosis (PT). In the US this disorder is called essential thrombocythemia or essential thrombocytosis.
You might have come to your doctor to ask about symptoms, or your doctor may have discovered a high platelet count when you had a routine blood test. Your doctor will run diagnostic tests to determine whether you have ET or some other condition.
It’s possible for conditions other than ET to cause a high platelet count. Your haematologist will need to rule out any other possible underlying causes before making a diagnosis. Some conditions that increase the platelet count include:
Many people with ET do not feel any symptoms at all. Others may experience symptoms such as:
If your haematologist suspects you have ET, he or she may suggest some of the following tests:
If you receive a diagnosis of ET, your haematologist may tell you that you are a low, intermediate or high-risk patient. Risk levels are based on a combination of features including your age, your symptoms - especially if you have had a blood clot - and your laboratory results. Your haematologist will consider your risk level when making recommendations about your treatment plan.
Treatment is a balancing act – patients and haematologists must work together to judge whether the benefits of treatment outweigh the downsides. The goal of ET treatment is reducing the risk of potential complications while keeping side effects to a minimum.
The first step in any treatment plan is to take good care of yourself. Maintaining a healthy body weight and controlling your blood pressure and cholesterol can go a long way toward protecting your long-term health. It is very important to stop smoking. Your GP or consultant can give you more information on how to best to care for your overall health.
In the early stages of ET you may not have any symptoms and you may be considered low-risk. If this is the case, your haematologist may suggest observation. Observation means that your ET will not be treated with medication (other than possibly low-dose aspirin), but that your medical team will test your blood from time to time for any sign of changes.
ET patients who have intermediate to high-risk have an increased risk of clotting (thrombotic) or bleeding (haemorrhagic) events, so the first goal of treatment is to reduce the likelihood of these events. Haematologists can use a number of different drugs to treat ET. The following treatments are the commonly used to treat ET – read more about them in our Treatment section.
People with ET are at high risk of blood clots (thrombosis) and bleeding (haemorrhagic) events. Medication can reduce the platelet count, make the platelets less ‘sticky’, and decrease the likelihood of bleeding and clotting complications. Clotting episodes are more common and can be serious. Examples of the different types of blood clots include those listed below. You can read more about preventing and coping with serious clots in our Living with MPDs section.
The risk factors for these clotting events include being over sixty years of age, your general health, and whether or not you have experienced a clot in the past. There are many other risk factors for heart attacks and stroke, including:
Bleeding complications are less common than clots. Bleeding problems are also less likely if your platelet count is lower than 1000 million per millilitre. Bleeding can appear in a variety of forms from easy bruising and nosebleeds to bleeding from the digestive system and sometimes in the brain.
Less common ET complications include a risk of developing acute myeloid leukaemia, (AML) or myelofibrosis (MF). Some of the drugs used to treat ET can slightly increase your risk of developing acute leukaemia. If you have any concerns about your treatment, please discuss this with your consultant.
If you have ET, your prognosis depends on many factors, including your age and whether you have other illnesses or complications.
ET patients who do not suffer from severe thrombotic (clotting) or haemorrhagic (bleeding) complications can probably expect a near-to-normal lifespan.
Some patients with ET develop acute myeloid leukaemia (AML) or myelofibrosis (MF) at a late stage of the illness. When ET ‘transforms’ to leukaemia or myelofibrosis, the outlook can be poor, as these diseases are often resistant to treatment. Your haematologist will monitor your blood and general health regularly. If there are any signs of leukaemia or myelofibrosis, your haematologist will find these and offer the appropriate treatment.
Your doctor may have found your high platelet count during a routine blood test, or after you experienced a clot.