What is the cause of hyperthyroidism leukocytes low?

Hyperthyroidism appears white blood cell low phenomenon, mainly thyroid hormone affects the human hematopoietic system, causing the proportion of peripheral blood lymphocytes increased, resulting in a decrease in the total number of white blood cells. In addition, when taking antithyroid drugs, it will also cause white blood cell low phenomenon, severe cases will also cause granulocyte deficiency phenomenon.