<prompt> An asymptomatic patient on regular health checkup has platelet counts of 8,00,000. Next line of management is:Follow up and observeBone marrow biopsyPlasmapheresisPhelobotomy Packed cell transfusion  <response>: A i.e. Follow-up and observeRef: Harrisons Principles of Internal Medicine, 19th edition, page 678Explanation:An elevated platelet count in an asymptomatic patient without cardiovascular risk factors requires no therapy.When the platelet count rises above 1 x 106pL, a substantial quantity of high-molecular-weight von Willebrand multimers are removed from the circulation and destroyed by the enlarged platelet mass, resulting in an acquired form of von Willebrands disease.THROMBOCYTOSISThrombocytosis, also called thrombocythemia, is generally defined as a platelet count greater than a defined upper limit of normal that may vary between 350,000pl to 600,000pl, depending on the laboratory or medical reference. The most common cut off for normal is 450,000pl.Elevated platelet counts are often an incidental or unexpected finding on a complete blood count CBC conducted to evaluate an unrelated condition.For those individuals found to have thrombocytosis without associated bleeding or thrombosis, the first challenge is to find the cause.The causes of thrombocytosis are separated into two categories:Autonomous primary thrombocytosisOccurs as a result of myeloproliferative disorders, myelodysplastic disorders, or rarely as a result of a hereditary condition.Reactive secondary thrombocytosis is:Most often a normal physiologic response to coexistent inflammatory condition e.g., infection, chronic inflammatory condition.Management of essential thrombocytosis by risk factorsRisk categoryRisk factorsManagementLowAge 60 and no prior cardiovascular eventNil. Follow-up and observeIntermediateGeneric cardiovascular risk factorsLow dose aspirin no consensusHighAge 60 andor prior cardiovascular eventsMyelosuppression Low dose aspirin 