Thrombocytopenia
（重定向自Thrombopenia）
Thrombocytopenia and thrombopenia refer to a disorder in which there is a relative decrease of thrombocytes, commonly known as platelets, present in the blood.
A normal human platelet count ranges from 150,000 to 450,000 platelets per microliter of blood. These limits are determined by the 2.5th lower and upper percentile, so values outside this range do not necessarily indicate disease. One common definition of thrombocytopenia that requires emergency treatment is a platelet count below 50,000 per microliter.