Why would someones white blood cell count be up...cancer/leukemia & lupus has been ruled out. White blood cell count seems to be rising slowly.

Would there be any suggestions to take to the doctor to run a test on something else? I know having a higher white blood cell count is an infection in the body, but what type of infection could it be? There is no change in body weight or level of energy. Thank you all, suggestions would be greatly appreciated!