High white blood cell count
Learn the causes of this increase in disease-fighting cells in the blood.
Definition
A high white blood cell count is a rise in the number of cells in the blood that fight infections.
What's thought of as high in a white blood cell count varies from one lab to another. This is because labs set their own reference ranges based on the people they serve. Most often, a count of more than 11,000 white blood cells in a microliter of blood is thought to be high for adults.
Causes
A high white blood cell count most often means one of the following has led to a rise in white blood cells:
- An infection
- Reaction to a medicine
- A bone marrow condition
- An immune system issue
- Sudden stress such as hard exercise
- Smoking
Specific causes of a high white blood cell count include:
- Allergy, mainly bad allergic reactions
- Asthma
- Bacterial, viral, fungal or parasitic infections
- Burns
- EGPA (formerly Churg-Strauss syndrome)
- Medicines, such as corticosteroids and epinephrine
- Hay fever
- Leukemia
- Lymphoma
- Myelofibrosis
- Polycythemia vera
- Pregnancy
- Rheumatoid arthritis
- Sarcoidosis
- Smoking
- Tuberculosis
- Vasculitis
- Whooping cough
When to see a doctor
A test a healthcare professional orders to diagnose a condition can show a high white blood cell count. A high white blood cell count rarely is found by chance.
Talk to your healthcare professional about what your results mean. A high white blood cell count plus results from other tests might show the cause of your illness. Or you might need other tests for more information about your condition.
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