Is 450 platelets normal?

The platelet content in the human body should be controlled within a normal range. If it is too high or too low, it will have a great impact on the human body. We often talk about the disease of low platelet count, but Xie Xiao is not very clear about the disease of high platelet count. So if someone tests their platelet count at the hospital and it is 450, is this a normal condition, and what causes it?

The platelet count constant is 100~300, and a count exceeding 400 is called thrombocytosis. There are two reasons: 1. Primary increase is seen in myeloproliferative diseases, such as chronic myeloid leukemia, polycythemia vera and essential thrombocythemia, early myelofibrosis, etc. 2: Secondary (reactive) thrombocythemia: The most common causes are bleeding, tissue inflammation and necrosis, malignant tumors, iron deficiency, post-splenectomy, Kawasaki disease, etc.

Causes

1. Reactive thrombocytosis

It occurs in infection, post-surgery, malignant tumors, post-splenectomy, acute blood loss or iron deficiency, trauma, non-infectious inflammation, etc. These causes lead to increased release of platelet-stimulating growth factors (such as thrombopoietin and interleukin-6), leading to thrombocytosis.

2. Spontaneous thrombocytosis

It is seen in myeloproliferative diseases, such as polycythemia vera, early myelofibrosis, chronic myeloid leukemia, etc.

3. Essential thrombocythemia

The pathogenesis may be related to changes in thrombopoietin and thrombopoietin receptors and activation of downstream pathways. 50% of patients with essential thrombocythemia have JAK2V617F gene mutation, 3% to 5% have MPL gene mutation, and 15% to 25% have CALR gene mutation.

Clinical manifestations

Patients with reactive thrombocytosis and spontaneous thrombocytosis have manifestations of the primary disease. Patients with essential thrombocythemia have an insidious onset of disease, with nonspecific symptoms such as fatigue and weakness, and are occasionally diagnosed based on a routine blood test or the discovery of an enlarged spleen. Patients have an increased incidence of thrombosis, including arterial thrombosis and venous thrombosis causing related symptoms. Some patients also experience headaches, visual symptoms, erythromelalgia, etc. due to microvascular thrombosis. A small number of patients have bleeding symptoms, including gastrointestinal bleeding, nose bleeding, gingival bleeding, hematuria, etc. 50% to 80% of patients have splenomegaly, which is mostly moderate, and splenomegaly is rare.

examine

Essential thrombocythemia

1. Complete blood test

The platelet count is ≥450×109/L, mostly between (600-3000)×109/L. The smear shows that the platelets are aggregated into piles, and occasionally giant, deformed or small platelets are seen. The white blood cell count may increase, (10-30)×109/L, and the classification is mainly neutrophils with segmented nuclei.

2. Bone marrow cytology examination

Nucleated cell proliferation is active or significantly active, and megakaryocyte proliferation is particularly obvious, characterized by an increase in large mature megakaryocytes and a large number of platelet aggregations.

3. Platelet and coagulation function tests

Platelet function is often abnormal, and in aggregation tests, platelet aggregation responses to collagen, ADP, and arachidonic acid are decreased. Bleeding time may be prolonged, prothrombin consumption time shortened, and blood clot retraction poor.

4. Gene mutation detection

JAK2V617F gene mutation can be found in 50% of patients, MPL gene mutation in 3% to 5% of patients, and CALR gene mutation in 15% to 25% of patients.