OVERVIEW

What is essential thrombocythemia?

Essential thrombocythemia (ET), also known as idiopathic thrombocythemia or hemorrhagic thrombocythemia, is a clonal proliferative disorder of hematopoietic multipotent stem cells.

The disease is characterized by persistent and significant elevation of peripheral platelet counts with abnormal function, excessive proliferation of megakaryocytes in the bone marrow, and is often clinically accompanied by bleeding, thrombosis, and splenomegaly.

Is essential thrombocythemia common?

Essential thrombocythemia (ET) is a rare hematologic disorder, with an incidence rate of approximately 0.4 to 2.5 per 100,000 people per year.

SYMPTOMS

What are the common manifestations of essential thrombocythemia?

• General symptoms: The onset is insidious, and symptoms vary. Mild cases may only present with fatigue and weakness, with no other symptoms. Some patients are diagnosed incidentally due to thrombocytosis or splenomegaly.

• Bleeding: Most patients seek medical attention due to bleeding tendencies. Common manifestations include gum bleeding, nosebleeds, skin purpura, and gastrointestinal bleeding. Bleeding episodes are often intermittent with long intervals.

• Thrombosis and embolism: Due to extreme thrombocytosis and increased platelet adhesiveness in some patients, arterial or venous thrombosis may occur. Common sites include the splenic, hepatic, mesenteric veins, lower limb veins, axillary artery, intracranial and peripheral arteries, often causing corresponding symptoms.

• Splenomegaly: About 25%–48% of patients have mild to moderate splenomegaly, mostly moderate, while massive splenomegaly is rare. Approximately half of the patients have mild hepatomegaly, usually without lymphadenopathy. 20% of patients may develop asymptomatic splenic infarction, leading to splenic atrophy. Splenectomy is contraindicated in this disease, as it may cause a further significant increase in platelets, leading to life-threatening thromboembolic complications.

What serious consequences can essential thrombocythemia cause?

Severe complications mainly arise from thromboembolic events, such as fatal pulmonary embolism caused by dislodged lower limb venous thrombosis. Additionally, studies have found that <2% of patients may progress to leukemia.

CAUSES

What causes essential thrombocythemia?

The exact cause of ET remains unknown. The main pathogenic mechanisms include:

• Activating mutations in the JAK2 tyrosine kinase gene (JAK2V617F), as well as JAK2 exon12 and CALR mutations, are associated with the pathogenesis.

• Gain-of-function mutations in the thrombopoietin receptor (MPL), such as MPLW515L/K.

Which populations should be particularly vigilant about essential thrombocythemia?

Essential thrombocythemia should be suspected in individuals with persistently elevated platelet counts and/or clinical thrombotic or hemorrhagic symptoms, as well as mild splenomegaly.

DIAGNOSIS

Essential Thrombocythemia: What Tests Are Needed?

Complete blood count (CBC), bone marrow examination, platelet and coagulation function tests, molecular biological tests.

Why Are These Tests Necessary for Essential Thrombocythemia? What Are Their Purposes?

• Complete Blood Count (CBC): Persistent elevation in platelet count, ≥450×10⁹/L, often accompanied by leukocytosis.

• Bone Marrow Examination: Hyperplasia of all cell lineages, predominantly megakaryocytes, with increased immature and mature megakaryocytes and abundant platelet formation. Bone marrow biopsy may reveal mild to moderate fibrosis.

• Platelet and Coagulation Function Tests: Most patients exhibit reduced platelet adhesion, abnormal ADP-induced platelet aggregation, and decreased platelet factor III effectiveness. Coagulation tests are generally normal, though some patients may show hypercoagulability. Bleeding time, prothrombin consumption test, and clot retraction may be abnormal.

• Molecular Biological Tests: Over 50% of ET patients test positive for the JAK2V617F mutation. Some JAK2V617F-negative ET patients may carry the MPLW515L/K mutation.

Which Diseases Are Easily Confused with Essential Thrombocythemia?

Secondary Thrombocythemia: Often secondary to splenectomy, hemolytic anemia, acute blood loss, chronic or acute infections, or neoplastic diseases.

TREATMENT

Which department should I visit for essential thrombocythemia?

Hematology.

How is essential thrombocythemia treated?

• The treatment goal of this disease is to prevent and treat thrombotic complications. Therefore, current treatment options are primarily based on the patient's thrombotic risk stratification. Doctors can choose different treatment plans depending on whether the patient has thrombosis.

• The ultimate goal of treatment: platelet count should be controlled at <600×10⁹/L, with an ideal target value of 400 × 10⁹/L.

• Commonly used cytoreductive drugs for this disease include:

• First-line drugs: Hydroxyurea, interferon. The specific drug choice is determined by the doctor based on individual circumstances.

• Second-line drugs: Anagrelide, busulfan, pipobroman, and ³²P. The specific drug choice is determined by the doctor based on individual circumstances.

DIET & LIFESTYLE

What should patients with essential thrombocythemia pay attention to in daily life?

• Avoid high-fat and high-salt diets, and keep blood pressure, blood sugar, and blood lipids within the ideal range;
• Avoid prolonged standing, sitting, or lying down;
• Seek medical attention immediately if the following symptoms occur:
• Redness and warmth in the hands and feet, often accompanied by a burning sensation;
• Tingling or other abnormal sensations in the fingertips, hands, or feet;
• Chest pain, headache, dizziness, weakness, etc.;
• Blurred vision or visible spots of light.

What should be considered in the care of patients with essential thrombocythemia?

Essential thrombocythemia is more common in the elderly. Older adults are more prone to thrombotic events in critical blood vessels (such as those of the heart and brain) because they often have conditions like atherosclerosis, which can itself lead to blood vessel blockages.

Therefore, while managing essential thrombocythemia, it is also important to schedule regular check-ups for the patient, encourage them to change unhealthy habits (such as excessive oil and salt intake, smoking, or lack of exercise), and maintain blood pressure, blood lipids, and blood sugar within the ideal range.

PREVENTION

Can essential thrombocythemia be prevented?

The pathogenesis of essential thrombocythemia is not yet fully understood, so there are no effective preventive measures.