Overview
Leukocytosis means the white blood cell (WBC) count is higher than normal. White blood cells are part of the immune system and help fight infection.
In many cases, an elevated WBC count is the body’s normal response to infection, inflammation, injury, or stress. Once the underlying problem is resolved, the count typically returns to normal.
However, when a high WBC count does not return to normal and no infection or inflammation is found, it may indicate something more serious—such as a bone marrow condition—requiring evaluation by a hematologist.
Causes
Many different conditions can increase WBC production. Common causes include:
Normal Immune Responses
Other Common Triggers
More Serious Causes
A WBC count above 11,000 cells/µL in adults is generally considered leukocytosis.
Symptoms
Leukocytosis itself may not cause symptoms. When symptoms do appear, they are usually related to the underlying condition, not the elevated WBC count alone.
Possible Symptoms Include:
How We Diagnose it
Your care team may use:
Blood Tests
Further Testing
If the cause is unclear or levels remain high, testing may include:
Your physician will consider your medical history, medications, symptoms, and trends in your blood counts over time.
Treatment Options
Treatment focuses on addressing the cause of the elevated WBC count.
Common approaches include:
Treating infection (antibiotics or antivirals if indicated)
Reducing inflammation
Adjusting medications that may contribute
Treating underlying chronic conditions
Most cases resolve once the underlying trigger is treated. Rarely, procedures such as leukapheresis may be used in severe cases to rapidly lower extremely high WBC counts.
Living With Leukocytosis
For many people, leukocytosis is a temporary finding and resolves on its own. Follow-up blood counts help ensure levels normalize. Persistent elevation may require hematology evaluation to rule out more serious causes.
When To See Your Provider
Seek urgent medical care if you experience:
Chest pain or trouble breathing
Severe headache, confusion, or stroke‑like symptoms
Bleeding that won’t stop
New abdominal, arm, or leg pain
Make an appointment if you notice fever, unexplained bruising, fatigue, weight loss, or if symptoms worsen.
Why Choose Illinois CancerCare
A blood disorder diagnosis can feel overwhelming. At Illinois CancerCare, we are committed to ensuring you never have to face it alone. Providing advanced, comprehensive hematology and oncology care for our patients is at the heart of everything we do. Since 1977, our specialists have focused on individualized, evidence-based treatment plans, access to world-class clinical trials, and thorough follow-up. With Illinois CancerCare, you can move forward with confidence knowing trusted expertise and compassionate support are always close to home.‑based treatment plans, access to world‑class clinical trials, and thorough follow‑up.
Sources & Patient Friendly References
Information sourced from Mayo Clinic and Cleveland Clinic.