What are possible causes of high white blood cell counts over a long period of time?

Bone Marrow stimulat: Inflammation, bad teeth, chronic bowel infections etc can cause high white counts. Bone marrow problems are usually dealt with by seeing a haematologist. They are in the best place to talk about the state of the individual, after the general doctor has sorted out the other components. If you have no symptoms, go and talk to your family doctor and make a plan.

Multiple: Normal white blood count/ WBC may range from 4, 600 to 10, 300 cells/ cubic mm. Slight elevation of WBC may be due to stress, infection, inflammation, auto-immune condition, etc. But persistently higher counts may suggest serious conditions including leukemia and lymphoma, esp. If there's accompanying symptoms, -fever, night sweats, weight loss . Go see a dr or a hematologist to appease your fear.