IN MANY of the myeloproliferative syndromes, such as polycythemia vera, primary hemorrhagic thrombocythemia, chronic granulocytic leukemia, and agnogenic myeloid metaplasia, platelet counts may be in excess of 1,000,000/cu mm. This is especially true of primary hemorrhagic thrombocythemia and agnogenic myeloid metaplasia when the spleen has been removed.1 Other conditions known to be associated with thrombocytosis, such as malignancy, iron deficiency anemia, and chronic inflammatory diseases (eg, rheumatoid arthritis or collagen disorders), are less likely to produce platelet counts in excess of 1 million. Even a patient who has had a splenectomy for other reasons will rarely have platelet counts above 1 million. Transient increases in platelets seen in the ten-day postoperative period do not appear to increase morbidity.
In the myeloproliferative syndromes, platelet counts in excess of 1 million are frequently associated with thrombotic episodes and hemorrhagic manifestations. Thrombosis tends to involve the large vessels, such as the mesenteric
Hoagland HC, Perry MC. Thrombocythemia (Thrombocytosis). JAMA. 1976;235(21):2330–2331. doi:10.1001/jama.1976.03260470048031
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