Skip to main content
Your session has expired. Reloading...

Doctor's Assessment Included

Every result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.

Hematology

Leukocytes in your blood: what high or low levels can mean

A leukocyte count measures the total number of white blood cells in your blood. White blood cells are a crucial part of your immune system and defend your body against infections, viruses, and other harmful invaders. Unlike red blood cells, which carry oxygen, white blood cells focus on defending against invaders. In young children the normal leukocyte count is often somewhat higher than in adults.

Reference Ranges

Male
10^9/l
Low 4 Normal 10 High
Female
10^9/l
Low 4 Normal 10 High

Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.

What It Measures

This test measures the total number of white blood cells per volume of blood. There are several types of white blood cells: neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Each type of white blood cell plays an important role in your defence.

Unlike red blood cells, which carry oxygen, these cells focus on defending against invaders. The test gives a useful overall picture of how active your immune system is.

Why It Matters

Your white blood cell count reflects how active your immune system is overall. A raised count may point to an infection, inflammation, or a stress response. A low count can suggest a weakened defence, a bone marrow problem, or the effect of certain medications. Monitoring helps with the early detection of immune-related conditions.

If your leukocytes are elevated, this can point to an infection, inflammation, or a stress response. A low value may instead relate to certain medications or conditions. Your GP can review your values in context.

When to Test

A leukocyte count is included in a complete blood count (CBC). Your GP may request it as part of a routine health check, when an infection is suspected, during treatment for a condition that affects your immune system, or to keep an eye on the side effects of medication.

Symptoms

Low Levels

A decreased white blood cell count (below 4.0 × 10⁹/L) is called leukopenia. It means your immune defences function less effectively. You often notice this by being more susceptible to infections: you get sick more often, recover more slowly, or develop infections you would not normally get. With a severely decreased count (below 1.0 × 10⁹/L), the risk of serious infections is significantly elevated and medical supervision is necessary.

High Levels

An elevated white blood cell count (above 10.0 × 10⁹/L) is called leukocytosis. The most common cause is an acute infection, where symptoms relate to the infection itself: fever, fatigue, pain, swelling, or coughing.

Leukocytosis also occurs in inflammatory diseases, allergic reactions, physical or emotional stress, and smoking. After intense physical exercise, the leukocyte count can temporarily rise without anything being wrong.

A very significantly elevated value (above 30 × 10⁹/L) without a clear infection warrants further investigation for a bone marrow disorder. This is rare, but a differential blood count can help identify the cause.

Lifestyle Tips

Your leukocyte count is primarily determined by your health status and is less modifiable through lifestyle than many other blood values. However, some factors play a role.

Smoking chronically elevates the leukocyte count and is one of the most common non-infectious causes of leukocytosis. Stopping smoking typically normalises the value within a few months.

Chronic stress and sleep deprivation can disrupt your immune system, causing leukocytes to either rise or fall. Regular exercise, adequate sleep, and stress reduction support stable immune function.

A varied diet with sufficient vitamins (particularly C, D, and B12), minerals (zinc, iron), and protein is important for the production of healthy white blood cells. With a demonstrable deficiency, targeted supplementation may be useful.

Frequently Asked Questions

What is a normal white blood cell count?
The normal value is between 4.0 and 10.0 × 10⁹/L (billion per litre). This applies to both men and women. In children, normal values are higher and age-dependent.
What does a high white blood cell count mean?
An elevated white blood cell count (leukocytosis) most commonly indicates an active infection or inflammation. Other causes include allergic reactions, smoking, stress, intense exercise, and in rare cases a bone marrow disorder.
What does a low white blood cell count mean?
A decreased white blood cell count (leukopenia) indicates reduced immune function. This can be caused by medication use (chemotherapy, immunosuppressants), viral infections that suppress the bone marrow, or autoimmune conditions.
Do I need to fast before a white blood cell test?
No, fasting is not required. The white blood cell count is not affected by food intake. The test is a standard component of the complete blood count.
Can stress affect my white blood cell count?
Yes, both acute and chronic stress can influence the white blood cell count. Acute stress (such as a fright response) can cause a temporary increase. Chronic stress can disrupt the immune system, causing values to either rise or fall.
What is the difference between a white blood cell count and a differential?
The white blood cell count gives the total number of white blood cells. The differential breaks this down into the five subtypes (neutrophils, lymphocytes, monocytes, eosinophils, and basophils). The ratio between these types helps identify the cause of an abnormal total.