hematology and oncology
Reactive Thrombocytosis (Secondary Thrombocythemia)
Introduction
Reactive thrombocytosis is an elevated platelet count (>450,000/mcL [>450×109/L]) that develops secondary to another disorder. (See also Overview of Myeloproliferative Neoplasms .) Some causes of reactive thrombocytosis include Chronic inflammatory disorders (eg, Rheumatoid Arthritis (RA) , Acute infection Hemorrhage Iron Deficiency None Hemolysis Cancer Splenectomy or hyposplenism There are also congenital familial thrombocytoses such as those due to thrombopoietin and thrombopoietin receptor gene mutations. For thrombocytosis that is not secondary to another disorder, see Essential Thrombocythemia . Platelet function is usually normal. Unlike in Essential Thrombocythemia , reactive thrombocytosis does not increase the risk of thrombotic or hemorrhagic complications unless patients have arterial disease. With secondary thrombocytosis, the platelet count is usually<1,000,000/mcL (<1000×109/L), and the cause may be obvious from the history and physical examination and with confirmatory testing as indicated. Complete blood count and peripheral blood smear findings may help suggest iron deficiency or hemolysis. If a cause of secondary thrombocythemia is not obvious, patients should be evaluated for a Overview of Myeloproliferative Neoplasms . Such evaluation may include testing for Treatment of the underlying disorder usually returns the platelet count to normal. 