Tertiary reduction is when the number of red blood cells, white blood cells, and platelets in the peripheral blood is below the normal range. Clinically, the diagnostic criteria for triple thrombocytopenia are: leukopenia, which is defined as a decrease in the number of leukocytes below 4,000 per milliliter of peripheral blood, and a decrease in the number of neutrophils below 2,000 per milliliter of blood. Red blood cell count is less than 4 million red blood cells per milliliter of blood and hemoglobin concentration is less than 120g/L for adult males, and less than 3.5 million red blood cells per milliliter of blood and hemoglobin concentration is less than 110g/L for adult females.Thrombocytopenia is a condition in which the number of platelets per milliliter of blood is less than 100,000, which is a diagnostic criterion for the reduction of all the three systems. At the same time, the more serious the reduction of the three systems, often means the more serious the disease, in the clinic, the most common disease of the three system reduction is aplastic anemia.