Increased platelet counts may synergistically accompany any condition in which the bone marrow has been stimulated.
In primary thrombocytosis, megakaryocytes are produced in the bone marrow at an increased rate, no longer being controlled by the normal regulatory mechanisms. This results in a marked increase in the number of circulating platelets. Causes of primary thrombocytosis include:
- Essential thrombocythemia
- Chronic myelogenous leukemia
- Polycythemia vera
- Myelofibrosis with myeloid metaplasia
- Idiopathic refractory sideroblastic anemia
Secondary (reactive) thrombocytosis is a platelet reaction to another process taking place in the body such as:
- Acute hemorrhage
- Chronic inflammatory disease
- Iron deficiency
- Acute bacterial infection
Thrombocytosis may also be transient, occurring after such things as vigorous exercise, epinephrine injection, or childbirth.
Platelets are increased in number. In primary thrombocytosis, the platelet count is usually >1000 x 109/L and most patients have abnormal platelet aggregation results.