What causes high white blood cell count and low platelet count?

The following are possible causes of high white blood cell count and low platelet count: 1. Acute upper respiratory tract infection—inflammation from infection can lead to increased white blood cell count, and the inflammatory response may trigger immune reactions in the body that reduce platelet levels. 2. Leukemia—both acute and chronic leukemia can present with elevated white blood cell counts and decreased platelet counts. If the abnormality is caused by infection, prompt treatment of the infection usually leads to a quick recovery. However, if these abnormalities persist, a bone marrow aspiration should be performed to determine whether leukemia is present.