What a high platelet count means
Platelets help blood clot. A count above the laboratory reference range, often around 450,000 per microlitre, is called thrombocytosis. It may be reactive, meaning the marrow is responding to another problem, or clonal, meaning the marrow is producing platelets abnormally.
Reactive causes are more common and include infection, inflammation, iron deficiency, recent surgery, trauma, bleeding, cancer and some medicines. The platelet count usually returns to normal when the underlying problem is treated.
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Reactive versus clonal thrombocytosis
Clonal thrombocytosis is suspected when the count is persistently high, the blood film shows abnormal platelet forms or other lineage abnormalities, or there are features of a myeloproliferative neoplasm such as an enlarged spleen, thrombosis, bleeding or a known JAK2, CALR or MPL mutation.
Essential thrombocythemia is diagnosed with sustained thrombocytosis, characteristic marrow findings and mutation testing, after reactive causes are excluded. Polycythemia vera, primary myelofibrosis and chronic myeloid leukaemia can also raise the platelet count and need different tests.
| Cause | Clue | Next step |
|---|---|---|
| Infection or inflammation | Fever, CRP rise, recent illness | Treat the cause and repeat the count |
| Iron deficiency | Low MCV, low ferritin, heavy periods | Iron studies and replacement |
| Essential thrombocythemia | Persistent count, JAK2 or CALR mutation | Marrow review and risk stratification |
| Post-splenectomy or surgery | Known clinical context | Observe and repeat |
Tests and treatment
Assessment includes a repeat blood count, blood film, iron studies, inflammatory markers and liver and kidney tests. Mutation testing for JAK2, CALR and MPL is used when a clonal disorder is suspected. A bone marrow biopsy is arranged when the diagnosis remains unclear or when myelofibrosis is a consideration.
Treatment depends on the cause and the risk of thrombosis or bleeding. Low-risk essential thrombocythemia may be monitored with aspirin in selected patients, while higher-risk disease may need cytoreduction with hydroxyurea, interferon or another agent. The target is to control the count and reduce complications, not simply to normalise a number.
Access and booking
Dr. Baniya consults at Kathmandu Neurology Clinic & Cognitive Center, Durbar Marg, and also practises at Kathmandu Cancer Center (KCC) Nepal, Civil Service Hospital, Kathmandu, and Advanced Care Hospital. Appointments are arranged at the Durbar Marg clinic or through the respective hospital or cancer centre. Bring all blood counts, blood film, marrow, flow cytometry and molecular reports.