I am 71 years old, female. In my latest annual checkup, the lab test showed my white cell count is 2.51 way below the normal range of 4.40. My past years records showed 3.1, 2.93, 2.68, 2.95 and 4.98 (last year). I saw a hematologist last year. He said I was okay. What could be possibly wrong with me? My family doctor told me I should check with an endoctriologist. Is she right? I feel physically very normal without any pain or discomfort. Occasionally I woke up in the middle of night due to this concern. Years back (about 15 years ago)I was being treated for hyperthyroid but got well by taking PTU, a German drug.