High white blood cell count

Symptoms

Definition

A high white blood cell count is an increase in cells in the blood that fight infections.

What's considered high in a white blood cell count varies from one lab to another. This is because laboratories set their own reference ranges based on the populations they serve. In general, for adults a count of more than 11,000 white blood cells in a microliter of blood is considered high.

Causes

A high white blood cell count usually means one of the following has increased the making of white blood cells:

  • An infection.
  • Reaction to a medicine.
  • A bone marrow disease
  • An immune system issue.
  • Sudden stress such as hard exercise.
  • Smoking.

Specific causes of a high white blood cell count include:

  • Allergy, especially severe allergic reactions
  • Asthma
  • Bacterial, viral, fungal or parasitic infections
  • Burns
  • Churg-Strauss syndrome
  • Medicines, such as corticosteroids and epinephrine
  • Hay fever (allergic rhinitis)
  • Leukemia
  • Lymphoma
  • Myelofibrosis (a bone marrow disorder)
  • Polycythemia vera
  • Pregnancy
  • Rheumatoid arthritis
  • Sarcoidosis
  • Smoking
  • Tuberculosis
  • Vasculitis
  • Whooping cough

When to see a doctor

A test a health care provider orders to diagnose a condition can reveal a high white blood cell count. A high white blood cell count is rarely found by chance.

Talk to your care provider 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.