3.16 WBC count. Back pain, fatigue. Normal ct, labs (blood work) came back great for a woman my age. So why is my WBC low? Is this a low-normal? .

It can be. The normal range is roughly 4-10.5. The differential is important. If the neutrophils are over 40% and you are not having recurrent infections or mouth sores, more work up may not be needed. If clinical concern, a bone marrow biopsy and aspiration could be performed, but very low yield given what we know so far.