Primary thrombocythemia in the young patient.

Primary thrombocythemia is typically a disease of older patients and frequently is associated with thrombosis and hemorrhage. Seven female and two male patients younger than 30 years were evaluated because of platelet counts exceeding 1 million/mm3. No hemorrhagic or thrombotic problems existed before diagnosis or developed during the follow-up period of 14 months to 10 years. Platelet function studies done in six of the nine patients showed absent aggregation with epinephrine and variable aggregation with adenosine diphosphate, as are seen in other chronic myeloproliferative states. One patient had spontaneous aggregation. Secondary causes of thrombocytosis were excluded. Only one patient received specific chemotherapy, which was given before 1973. Thus, thrombocythemia without a secondary cause appears to be much more benign in the young patient than in the older, and aggressive chemotherapy to lower the platelet count is not necessarily justified unless serious complications develop.