White Blood Cell (WBC) Count Test

This test counts the total number of white blood cells in a microliter of your whole blood, reported in thousands per microliter. It does not separate the result into neutrophils, lymphocytes, monocytes, eosinophils and basophils; that breakdown, called the differential, is part of the CBC with Differential.

People whose clinician wants their white cell count followed, for example while taking a medicine that can lower it; people re-checking a previous high or low WBC; and people with a known condition affecting white cells. If you have signs of infection such as fever, chills or a wound that will not heal, see a clinician; for a general check, choose the full CBC with differential.

Any time of day, with no fasting. The count can rise temporarily during an infection, with stress or in pregnancy, so if you are checking your baseline, test when you are well. When monitoring a medicine, follow the schedule your prescribing clinician sets.

Quest's reference range for adults over 18 is 3.8-10.8 thousand per microliter (children have higher, age-specific ranges). A high count (leukocytosis) is most often due to infection, and can also reflect inflammatory disease such as rheumatoid arthritis, allergy, tissue damage from burns or surgery, smoking, stress, pregnancy, a medicine reaction or, less often, leukemia. A low count (leukopenia) can result from bone marrow damage from infection, disease or treatments such as chemotherapy, cancers affecting the bone marrow, autoimmune disorders such as lupus, HIV, or liver or spleen disease. A WBC count alone cannot confirm a diagnosis; clinicians interpret it with the differential, the rest of the CBC and your symptoms. Review your result with a clinician, and seek care promptly if a low count comes with fever. JustLabs results are informational and do not replace medical care.