Had my annual physical October 22. My WBC was found to be 2.7 and neutrophils 38. This was very alarming to me, because I am very healthy, I take no meds and I am aware of many reasons that a wbc count can be low. I asked a doctor friend of mine, what he thought I should do. He advised me to have it rechecked right away. I called my doctor's office; who was very reluctant to have it rechecked but consented to have it done. On November 1st my recheck showed that my WBC was 4.0. My doctor explained many logical reasons for the variation in the results, possible viral infection was one reason. I recommend that if you experience this to make sure the result is accurate by having a recheck of your lab work or having it rechecked at a later date as recommended by your doctor.
Blood tests are only a snapshot of what is occuring that second, it can change. If the doctor is not worried, then relax, however, by all means get another test if he recommends it, any illness can affect the WBC reading.