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Did you know why essential thrombocythemia is accidentally discovered during a routine blood test?
Essential thrombocythemia (ET) is a rare, chronic blood cancer and myeloproliferative neoplasm characterized by excessive production of platelets by megakaryocytes in the bone marrow. Patients often have no obvious symptoms at the time of diagnosis and are diagnosed unexpectedly because of elevated platelet counts during routine blood tests. How did this happen?
Symptoms and signs
Most people with essential thrombocythemia will not have any obvious symptoms at the time of diagnosis. Compared with other blood cancers, the symptoms of ET are relatively difficult to detect. The most common symptoms include:
Bleeding (due to abnormal platelet function), blood clots (such as deep vein thrombosis or pulmonary embolism), fatigue, headache, nausea, vomiting, abdominal pain, visual disturbances, dizziness, fainting, and paralysis of the limbs.
During a physical examination, the most common signs are an increase in the number of white blood cells, a decrease in the number of red blood cells, and an enlarged spleen.
Cause analysis
In cases of ET, the sensitivity of megakaryocytes to growth factors is increased, leading to activation of produced platelets, which in turn increases the potential for thrombosis. When the number of platelets exceeds 1 million, von Willebrand factor (vWF) may be trapped by excess platelets due to excess platelets, resulting in insufficient vWF formation for platelet adhesion, thereby increasing the risk of bleeding.
JAK2 kinase (V617F) mutations are present in 40-50% of cases and their presence confirms the diagnosis.
Additionally, in patients lacking JAK2 or MPL mutations, calreticulin mutations were discovered in 2013, becoming the second most common mutation in hematoproliferative neoplasms. These mutations affect the final exon, causing a shift in the reading frame, causing the formation of new terminal peptides, and triggering the loss of endoplasmic reticulum retention signals.
Diagnostic criteria
According to the diagnostic criteria proposed in 2005, the diagnosis of essential thrombocythemia requires the following conditions to be met at the same time:
- A1: Platelet count > 400 × 10³/μL for at least 2 months
- A2: Existing V617F JAK2 mutation
- B1: Reactive thrombocythemia without other causes
- B2: No evidence of iron deficiency
- B3: No evidence of polycythemia
- B4: No evidence of chronic myelogenous leukemia
- B5: No evidence of myelofibrosis
- B6: No evidence of myelodysplasia
Treatment methods
Not all cases require treatment, and patients are often classified as low or high risk based on age, medical history and blood test results. Low-risk patients are usually treated with aspirin, while high-risk patients may be treated with hydroxyurea, interferon-alpha, or anglido.
There are currently unapproved drugs in clinical trials, such as bomedemstat, that are expected to lower platelet counts.
In patients with ET, hydroxyurea reduces the incidence of arterial blood clots, and Aglitide reduces the incidence of serious bleeding in some cases.
Prognosis and epidemiology
Essential thrombocythemia is generally described as a slowly progressive disease with long asymptomatic periods that may be accompanied by thrombotic or hemorrhagic events. And under good medical control, the average lifespan of patients is not much different from that of non-ET patients. According to statistics, the annual incidence of ET is approximately 0.6-2.5/100,000, with most cases occurring between the ages of 65 and 70, with a higher incidence in women than men.
Association with pregnancy
During pregnancy, hydroxyurea and anglitide are contraindicated because essential thrombocythemia increases the risk of miscarriage threefold. Therefore, the mother and fetus need to be closely monitored and treated with low-dose low-molecular-weight heparin if necessary.
Conclusion
Essential thrombocythemia is often discovered accidentally during routine blood tests. Its subtle characteristics and multiple complex conditions caused by mutations make the diagnosis process extremely difficult. Have you ever thought about how to detect and treat this type of invisible blood cancer more effectively in the future medical development?
