Your blood work results are in and your white blood cell (WBC) count is flagged as high. Even if you feel fine, that result alone can raise questions and concerns.
White blood cells play an important role in keeping you healthy. They protect your body from infection, support healing and respond to stress. So what does it mean when your WBC count is high?
“A white blood cell count reflects how active the immune system is at that moment in time,” said Danielle Nance, MD, a hematologist with Banner Health. “Most of the time, it’s a normal response to being alive.”
We spoke with Dr. Nance to understand common reasons it may be elevated, how doctors determine the cause and when you should follow up with your health care provider.
What is a white blood cell count?
A white blood cell count is part of a complete blood count (CBC) test. It measures the number of immune cells moving around in your bloodstream.
White blood cells are not all the same. “There are different types of white blood cells and each plays a different role in defending the body against infection, wounds and other stress,” Dr. Nance said.
There are five types of white blood cells:
- Neutrophils: Protect against infections by killing pathogens like bacteria and fungi
- Lymphocytes: Protect against viral infections and produce proteins to help fight infection
- Monocytes: Break down bacteria and clean up dead cells in the body
- Basophils: Produce an allergic response like hives, sneezing or a runny nose
- Eosinophils: Identify and destroy parasites and play a role in allergic responses
What “high” means
For most adults, a normal WBC count ranges from about 4,000 to 11,000 cells per microliter of blood. Normal ranges can vary slightly by age, health factors and the lab performing the test.
When your white blood cell count is above the normal range, it’s called leukocytosis. This is the term you may see listed on your lab results.
“Leukocytosis doesn’t point to a specific diagnosis on its own,” Dr. Nance said. “It simply means the immune system is responding to something.”
Common causes for a high white blood cell count
A high WBC count can happen for many reasons. Some causes are temporary and go away on their own. Others are chronic (long-lasting) and may need further investigation.
Infections
Infections are the most common cause of leukocytosis.
“Viral, bacterial and fungal infections can all trigger the body to make more white blood cells to fight off germs,” Dr. Nance said.
Infections like pneumonia, urinary tract infections and strep throat can all spike WBCs.
Inflammation
Chronic, inflammatory conditions can also raise WBC levels, including
- Arthritis
- Asthma
- Allergies
- Inflammatory bowel disease like Crohn’s disease
Ongoing inflammation keeps the immune system activated, which can increase counts.
Stress on the body
Physical and emotional stress can temporarily increase WBCs.
“People with very stressful jobs can have higher white blood cell counts due to chronic stress,” Dr. Nance said. “Surgery, injury, trauma or intense exercise can also cause a short-term increase.”
Dr. Nance notes that being overweight can also contribute to higher-than-normal levels.
Medications
Some medications can affect WBCs.
“Corticosteroids, such as those used during an asthma flare, can raise white blood cell levels,” Dr. Nance said. “But most medications don’t cause this.”
Smoking and nicotine use
Smoking and other nicotine products can lead to chronic, mild elevations in WBCs.
Blood and bone marrow disorders (less common)
In rare cases, leukocytosis can be caused by conditions that affect how blood cells are made.
“Sometimes, white blood cells are increased because of cancer but most of the time, they’re not,” Dr. Nance said. These causes are typically considered only when counts are high, persist over time or occur alongside other abnormal lab findings.
Symptoms that may come with a high white blood cell count
Symptoms depend on what’s causing the increase. Some people feel sick, while others feel completely fine.
Possible symptoms include:
- Fever, chills or night sweats
- Fatigue
- Body aches
- Coughs, congestion or sore throat
- Abdominal pain
“If an infection or injury is present, people may have symptoms like fever, chills, cough or abdominal pain,” Dr. Nance said. In many cases, there are no symptoms and leukocytosis is found on routine blood work.
When should I worry about a high white blood cell count?
In many cases, a high WBC is not something to immediately worry about. It is normal for blood cell count to go up and down, so usually you don’t need any additional evaluation.
“If there are concerns, your provider may refer you to a hematologist or blood doctor,” Dr. Nance said. “They can review lab results, examine blood cells under a microscope and determine if additional testing, if any, is needed.”
Contact your provider if:
- Your WBC count is very high or continues to rise
- You have symptoms like fever, shortness of breath or severe pain
- You have a chronic condition with new or worsening symptoms
- You’re unsure what your lab results mean
Your provider can help you understand your results and next steps.
Ways to support a healthy white blood cell count
You can’t always control your WBC levels but you can support your immune system and overall health.
- Take care of infections: If you’re sick or injured, follow your provider’s guidance and finish prescribed treatments. This helps your body recover and return to normal balance.
- Manage chronic conditions: Keep conditions like asthma and inflammatory disorders well controlled to reduce ongoing inflammation and stress.
- Reduce stress when possible: Chronic stress can raise WBC counts. Get enough sleep, stay physically active and find ways to manage stress.
- Avoid smoking and nicotine: Quitting can improve overall health and reduce strain on your immune system.
- Maintain a healthy lifestyle: Eat a balanced diet, exercise and maintain a healthy body weight.
Takeaway
A high white blood cell count, or leukocytosis, is often your body’s normal response to infection, inflammation or stress. In most cases, it’s temporary and improves as the underlying cause resolves.
If you have questions about your lab results or symptoms, a Banner Health specialist can help you understand what’s behind the numbers and guide your care.
