Abnormal proliferation of the cells that produce blood platelets, leading to an excess of platelets in the blood and increasing risk either of thrombosis or of bleeding.
〔医〕血小板增多（症）
Example sentencesExamples
The blood dyscrasias that most commonly lead to leg ulceration are sickle cell disease, thalassaemia, thrombocythaemia, and polycythaemia rubra vera.
Erythromelalgia, a symptom complex of painful inflammatory vasodilatation of extremities, is usually idiopathic or due to thrombocythaemia.
I was diagnosed as having essential/primary thrombocythaemia three years ago.
Dehydration during the marathon combined with an underlying thrombocythaemia probably precipitated his thrombosis.
We report the clinical findings in a patient with essential thrombocythaemia who presented with partial third nerve paralysis.