Essential thrombocythemia (ET, PT, primary or idiopathic thrombocythemia) is a form of blood cancer in which there is an excess production of platelets. This increases the risk of blood clots (thrombosis). Read here how the disease progresses and how it is treated!
ICD codes for essential thrombocythemia : D47
- What is essential thrombocythemia? Essential thrombocythemia (ET) is a chronic disease of the bone marrow. Due to a significantly increased production of blood platelets (thrombocytes), the risk of blood clots increases.
- Course and prognosis: ET cannot be cured, but can be treated well with medication. Those affected have an almost normal life expectancy. If detected and treated early, the prognosis is good.
- Treatment: reduction of the tendency to blood clots, specific therapy with drugs (acetylsalicylic acid, chemotherapy, other active ingredients)
- Symptoms: Headaches, dizziness, blue fingers and toes, blurred vision, bruising, ringing in the ears, tinnitus, nose or gum bleeding, fatigue, stroke, heart attack, thrombosis, pulmonary embolism, upper abdominal pain.
- Causes: Acquired gene change (mutation) in the blood-forming cells of the bone marrow.
- Risk factors: Genetic predisposition (familial accumulation).
- Diagnostics: symptoms, blood test, ultrasound test, molecular genetic test
- Prevention: No specific prevention possible
What is essential thrombocythemia?
Essential thrombocythemia (ET, PT, primary or idiopathic thrombocythemia) is a chronic disease of the bone marrow. Along with polycythemia vera (PV), chronic myeloid leukemia (CML) and primary myelofibrosis (PMF), it is one of the myeloproliferative diseases. This refers to blood cancers that originate in the blood-forming cells of the bone marrow (stem cells).
In essential thrombocythemia, the blood platelets (thrombocytes) multiply largely uncontrollably. They are responsible for blood clotting : Even with the smallest of injuries, the blood platelets attach themselves to the damaged tissue, clump together and form a plug that seals the injured blood vessel. In the case of external injuries, the visible result of this process is the formation of a scab.
If there are too many platelets in the blood, as in ET, the risk of blood clots increases. The platelets clump together even without injury. Clots form (thrombosis) which block the blood vessels (embolism). Tissues or organs behind the blood clot become starved of oxygen and die. In the worst case, vital organs such as the heart (heart attack) or brain (stroke) are affected.
Paradoxically, it is also possible that those affected have an increased tendency to bleed. The reason for this is that the blood platelets bind clotting factors. If platelets are present in excess, they filter out a large number of clotting factors. These are then missing for blood clotting and the tendency to bleed increases. Signs of this are frequent or severe bleeding from the nose or gums.
“Essential” or “idiopathic” means that there is no identifiable cause for the high platelet count. Conversely, platelets are also elevated when there is inflammation, iron deficiency, or internal bleeding. The doctor then speaks of secondary thrombocythemia.
Normally, the platelet count in healthy people is between 150,000 and 450,000 per μl of blood. In the case of thrombocythemia, the blood of the sick person sometimes contains well over a million platelets per μl of blood.
Compared to other myeloproliferative diseases such as polycythemia vera (PV) and primary myelofibrosis (PMF), essential thrombocythemia is usually mild and life expectancy is almost normal. However, the course of the disease varies significantly from case to case. While the quality of life of most patients is not or only slightly affected, others feel ill and have difficulties in coping with everyday life.
If, for example, they are unable to go about their work, those affected have the option of applying for a rehabilitation measure (cure). In the case of persistently severe symptoms, you also have the option of submitting an application to the responsible social security office for the determination of a severe disability.
Essential thrombocythemia is a rare disease: it is estimated that 2.4 per 100,000 people develop it each year, women twice as often as men. It occurs more frequently between the ages of 50 and 70, younger people are less frequently affected. In five percent of cases, it is children who develop ET.
Is essential thrombocythemia fatal?
It is difficult to predict how essential thrombocythemia will progress, since the disease takes an individual course in each patient. Usually, ET is not fatal.
Although ET is a form of blood cancer, with appropriate treatment, patients have a near-normal life expectancy. Compared to other myeloproliferative disorders, essential thrombocythemia is relatively benign.
Most patients live for many years or even decades without symptoms. Complications such as vascular occlusion do not necessarily occur. However, the risk is higher compared to healthy people.
In rare cases, the disease progresses. Within 15 years, about five to ten percent of patients develop osteomyelofibrosis. The bone marrow scars and progressive anemia occurs. Acute myeloid leukemia (AML), a malignant form of blood cancer, develops from ET in about three percent of patients.
Can ET be cured?
Essential thrombocythemia is a chronic disease of the bone marrow. Since the cause of the disease is a change (mutation) in the genes of the stem cells in the bone marrow, a cure is not possible – but it can be treated well with medication.
The disease progresses differently in each patient. Therefore, there is no uniform therapy recommendation. How ET is treated depends on the age of the patient, the stage of the disease, the symptoms and the individual risk of thrombosis.
As long as there are no symptoms, ET patients do not need treatment. However, it is important for patients to have regular check-ups. Doctors speak of “wait and see”.
General measures to reduce the risk of thrombosis
- Normal weight
- Regular exercise
- Balanced nutrition
- Drink enough
- No long sitting
- Travel compression stockings
- Treat risk factors such as arterial hypertension, diabetes, hypercholesterolemia
- Do not smoke.
ET patients who develop symptoms are given medication therapy. Since it is a chronic disease, patients must take the medication for life.
Acetylsalicylic acid: If the first symptoms appear that indicate circulatory disorders , such as blue fingers or toes, patients are given the active ingredient acetylsalicylic acid. It has a blood-thinning effect and thus prevents blood clots.
Chemotherapy: If acetylsalicylic acid has no effect or if treatment with it is not possible (e.g. if there is an increased tendency to bleed), patients receive chemotherapy with the active ingredient hydroxyurea. It is the drug of first choice for ET. Hydroxyurea inhibits the growth of blood platelets. Chemotherapy causes the number of platelets to decrease. The same applies if complications such as thrombosis, heart attack or stroke have already occurred.
Alternatively, the doctor treating you uses the following active ingredients:
- Anagrelide (AG): inhibits the maturation of progenitor cells and in this way restricts new formation
- Interferon-alpha: also reduces platelet counts, but does not work in all patients.
What are the symptoms of essential thrombocythemia?
Most patients live years without symptoms. However, over time, the increase in platelets increases the tendency for poor circulation and blood clots.
Possible symptoms are:
- Blue fingers and toes (as a sign of circulatory problems)
- Visual disturbances
- Bruising (hematoma) with hardening or swelling that is slow to go away
- Ringing in the ears, tinnitus
- Leg cramps
- Pain in the legs
- Bleeding gums
- Heavy or light menstruation
- Painful redness, swelling, tingling, burning, or numbness in your fingers or toes
- Heart attack
- Thrombosis in the deep leg arteries (deep vein thrombosis)
- Pulmonary embolism
- Abdominal vein thrombosis
- Upper abdominal pain (enlargement of the spleen and/or liver).
In the event of sudden shortness of breath, swelling of the legs or chest pain, call an ambulance immediately!
Causes and risk factors
In most cases, the cause of essential thrombocythemia is a gene change (mutation) in the blood-forming cells (stem cells) in the bone marrow. All blood cells develop from these stem cells. As in some other myeloproliferative disorders (CML, PV, PMF), ET involves a mutation on chromosome 9. In the case of ET, it leads to the blood platelets multiplying largely uncontrollably. So far, three different gene changes have been identified that trigger ET.
JAK2 mutation : Around 50 percent of all ET patients carry the JAK2 mutation. JAK stands for Janus kinase, an enzyme that plays an important role in signal transduction. The enzyme is permanently activated in cells that carry this mutation. The cells are constantly dividing. In essential thrombocythemia, it is primarily the blood platelets that multiply uncontrollably.
CALR mutation: In some patients, the CALR mutation (calreticulin mutation) triggers the disease. The protein calreticulin is affected here.
MPL mutation: A genetic change in the so-called thrombopoietin receptor (also a protein) is a possible trigger for ET.
In a very small number of ET patients, none of the three gene changes can be detected. Doctors refer to these as “triple negative”.
How does the genetic change come about?
It is not clear why such genetic changes occur. Essential thrombocythemia is not congenital, but only develops over the course of life. Possible – but not yet certain – triggers are radioactive radiation, viral infections and chemical substances as well as age, with which the probability of gene mutations increases.
Even if the disease is not directly passed on to the offspring, doctors suspect a certain genetic predisposition. It is striking that ET occurs more frequently in affected families.
Examination and diagnosis
ET causes no symptoms in most patients for years and even decades. The diagnosis is therefore often made incidentally during routine examinations. The blood test initially shows high platelet counts.
In other cases, patients come to the doctor because they suffer from headaches or blurred vision, have blue fingers or toes, or have suffered a thrombosis.
If essential thrombocythemia is suspected due to the large number of platelets in the blood, a specialist in blood diseases (haematologist) is the right contact person.
The doctor carries out the following examinations:
Blood test: When analyzing the blood, high platelet counts (> 450,000 per μl of blood) are noticeable.
Ultrasound examination of the abdomen: The spleen has the task of breaking down changed and old blood platelets. Since a particularly large number of platelets are formed during ET, the spleen enlarges as the disease progresses. This change can be clearly seen on ultrasound.
Molecular genetic testing: The molecular genetic testing aims to detect gene changes. To do this, the doctor takes blood from the patient and analyzes the blood cells for mutations. Corresponding changes (JAK2, CALR or MPL mutations) can be detected in most ET patients. In “triple negative” patients, on the other hand, no genetic changes are found.
Bone marrow biopsy: During a bone marrow biopsy, the doctor removes a small sample of tissue from the bone marrow. The pathologist then examines the removed cells under the microscope. Since the blood platelets have a typical appearance in ET, the disease can be clearly identified by this examination.
The doctor usually takes the bone marrow sample from the pelvic bone. For this, the patient lies on his side or stomach. The doctor numbs the area, disinfects it, and sticks a special needle through the skin and pelvic bone into the bone marrow. The puncture is usually not painful, but some people feel a brief ache when the doctor opens the syringe to collect the sample.
A bone marrow biopsy Is usually performed on an outpatient basis and under local anesthesia, sometimes under a brief general anaesthetic.
Essential thrombocythemia is a disease that develops over the course of life. Since it has not yet been clarified why this happens, there are currently no concrete measures to prevent the disease.
Reduce personal risk of thrombosis
Patients who have already been diagnosed with ET reduce their personal risk of thrombosis by taking the following measures:
- Refrain from nicotine.
- Get regular exercise; Endurance sports and vein gymnastics are ideal
- Drink enough, preferably 1.5 to 2 liters of water or unsweetened tea daily
- Avoid being overweight ; eat a healthy and balanced diet
- Wear thrombosis stockings on long car journeys or long-haul flights; try to move in between
- Treatment of diseases that increase the risk of thrombosis: cardiovascular diseases, diabetes mellitus, high cholesterol.
It is important for ET patients to have regular check-ups with their doctor.
- Clinical examination
- Blood test: initially every one to two weeks, during the stable phase every four to twelve weeks, then every six months
- Annual abdominal (spleen) ultrasound
- Bone marrow aspiration if disease progression is suspected.