White blood cell counts are a good indicator of immune system function. Elevated white blood cell counts can indicate bacterial or viral infection, though bacterial is more common. Other causes of elevated counts include an autoimmune disorder, deficient immune system, and blood disorder. Common symptoms of high white blood cell count include headache, dizziness and possible localized symptoms of inflammation.

Patients with lower than normal white blood cell counts are considered unhealthy. Low counts can be contributed to sepsis, autoimmune disorders, lymphoma or conditions that affect bone marrow function.

The test is nearly always ordered as part of a complete blood count, or CBC. CBCs are typically ordered as part of a yearly physical exam and used as a diagnostic tool.

Normal White Count Ranges

• Negative Pregnancy Adult: 3.5 to 9.1X103/mm3X103/µl or 3.5 to 9.1X109/L
• Pregnancy Trimester One: 5.7 to 13.6X103/mm3X103/µl or 5.7 to 13.6X109/L
• Pregnancy Trimester Two: 5.6 to 14.8X103/mm3X103/µl or 5.6 to 14.8X109/L
• Pregnancy Trimester Three: 5.6 to 16.9X103/mm3X103/µl or 5.6 to 16.9X109/L