I had a CBC done in september and my WBC was 7.4, I just had another done recently as a routine visit and the WBC was 5.8. Should I be concerned about the drop in WBC? Both numbers are still normal and in reference range, but I can't help but think. My RBC and Platelets were normal and no where near the "low" mark. If this was Leukemia, wouldn't something else show up abnormal in the blood?