My white blood cell count was extremely low, 3.4 thousand/ul, what does this mean?

Wbc: white blood cell counts vary from minute to minute, hour to hour, day to day. A WBC count of 3.4 is not that low and does not necessarily mean that you are in danger. It could just reflect your bodies response to a minor viral infection. Often people of Asian or African American descent can have lower WBC counts and that can be normal for them. I would have your WBC count repeated first

Borderline: That will be borderline leukopenia. It also depends on the lower range for that specific lab. To better define it we use the differential where we can decide which fraction- neutrophils/ lymphocytes/ monocytes/ is decreased. Talk to your doc about your worries.

Virus: Viral infections can actually cause a low WBC. This is the most common condition and is not dangerous. Other conditions such as aplastic anemia, cancer, autoimmune disorders and immunocompromising diseases can lower WBC as well. In the absense of any other symptoms your FP will probably want to recheck the count in a week or two.

Leukopenia : Leukopenia could be a normal variant especially in African-American people. Most common causes of Leukopenia are acute virus infection, HIV, Hepatitis B and C, some bacterial infection, Vitamin b12 deficiency and medications. To make a diagnosis it's important to know the differential of WBC and also other cell lines like Red blood cells and Platelet count. Talk to your Provider for evaluation