Thrombocythemia

Thrombocythemia is a condition of high platelet (thrombocyte) count in the blood. Normal count is in the range of 150,000 to 450,000 platelets per microlitre of blood.
When the cause is unknown, the term thrombocythemia is used, as either primary thrombocythyemia or essential thrombocythemia. This is caused by problems found in the bone marrow, cells that overproduce the platelets. The cause of these problems is unknown.