1) Symptom 
Thrombocytosis (or thrombocythemia) is the presence of high platelet counts in the blood, and can be either primary (also termed essential and caused by a myeloproliferative disease) or reactive (also termed secondary). Although often symptomless (particularly when it is a secondary reaction), it can predispose to thrombosis in some patients. In a...
increased numbers of platelets in the peripheral blood.
<haematology> Increased numbers of platelets in the peripheral blood. ... (18 Nov 1997) ... 
(throm″bo-si-to´sis) an increase in the number of circulating platelets; it may be essential or primary (see essential thrombocythemia) or secondary to a disease process such as an infection, inflammation, neoplasm, or rheumatoid process. Called also thrombocythemia.
Type: Term Pronunciation: throm′bō-sī-tō′sis Definitions: 1. An increase in the number of platelets in the circulating blood. Synonyms: thrombocythemia
Thrombocytosis: See thrombocythemia.
[n] - increase in the number of platelets in the blood which tends to cause clots to form
noun increase in the number of platelets in the blood which tends to cause clots to form; associated with many neoplasms and chronic infections and other diseases