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White blood cells

A white blood cell or WBC count is a common blood test, usually done during a complete blood count, that measures how many white blood cells are in the body. This test is also known as a leukocyte test. A complete blood count (WBC) is usually included in a common screening test for conditions that may affect your overall health.

White blood cell count is the general term for the number of white blood cells in the body. Different white blood cells are in the body, and the blood contains a certain percentage of each. Some conditions, such as an infection, can increase or reduce the white blood cell count.

Why is a white blood cell count necessary?

A WBC count is usually part of a CBC. Your doctor will likely order this test during your routine blood test. White blood cells (leukocytes) are an essential part of the body’s immune system.

The body produces these cells in the bone marrow but transports them through the bloodstream. White blood cells fight infection by attacking germs, viruses and bacteria that invade the body. A WBC count can diagnose infection in the body and help the doctor know about undiagnosed medical conditions such as immune deficiencies, blood disorders, and autoimmune diseases. 

The WBC count can also help the doctor monitor the effectiveness of radiation treatment, chemotherapy and other therapies people with cancer need.

White blood cell differential

Your doctor may recommend a white blood cell count differential. This test gives a breakdown of the white blood cell count, separating the count of different white blood cells to determine if they are within the normal range.

Five major types of white blood cells are available, and each plays a different role in protecting the body from infection and getting rid of infected cells. The main types of white blood cells include:

Normal WBC count

If your white blood cell count is normal, your immune system functions properly. The normal white blood cell count is between 4000 and 11,000/microliters.

Different factors, such as sex and age, determines the normal WBC count. The following are the normal white blood cell count ranges for the groups below.

Age range WBC per microliter (µL) of blood
Children 5000 – 10000
Adult women 4500 – 11000
Adult men 5000 – 10000

Pregnant women may have a varying white blood cell count from the above ranges. Children under two years and newborns may also have different WBC from the above range.

The normal ranges may also vary in different labs. The lab performing your test will include the reference range on your report.

Another measurement for blood volume is cubic millimetres (mm3). A cubic millimetre and a microliter are the same amounts.

The normal percentage of the WBC in the overall count is within the ranges in the table below.

Type of  WBC Normal percentage of the overall WBC count
Basophil 0.5 – 1%
Eosinophil 1 – 4%
Monocyte 2 – 8%
Lymphocyte 20 – 40%
Neutrophil 55 – 70%

An underlying condition may be present if your white blood cells are higher or lower than the normal ranges.

A high or low WBC count may indicate a blood disorder or other medical condition. Your doctor will consider several factors to determine the specific cause of your low or high WBC count, such as your medical history, symptoms and current medications.

Low white blood cell count

A low WBC count is medically knowns as leukopenia. This may result from the following:

A low white blood cell count may also be known as neutropenia, but this term is usually for a low number of neutrophils. Leukopenia usually results from a low number of neutrophils.

Neutropenia can increase your risk of illness, infection, and death because you may have insufficient white blood cells to protect you from bacteria and germs. If you have neutropenia, ensure you take precautions such as wearing a mask in public areas to reduce your risks and exposure to infection.

High white blood cell count

A high WBC is known as leucocytosis, and it can result from:

High WBC may be long-lasting or chronic with the following conditions 

Your doctor may order additional tests to determine why you have an abnormal white blood cell count. After diagnosing why you have a low or high WBC and recommending the right treatment, you will have periods WBCs and other tests.

If the WBC count remains low or high, it means the conditions may be worse, but your doctor will use the information to recommend a better treatment. A normal WBC count from retesting indicates the treatment is working.   

Symptoms of abnormal WBC count

The symptoms of a low WBC include:

A high WBC doesn’t usually cause symptoms, but the underlying conditions that cause the elevated count may cause their symptoms.

If you show symptoms of a low WBC, your doctor will order a WBC count. The doctor may also order a CBC, which includes a WBC count.

Preparing for a WBC count

No specific preparation applies for a WBC. You can schedule the appointment for your WBC count at any time.

Some medications can either increase or lower your WBC count. These medications include:

Before your blood sample collection, inform the healthcare provider of your non-prescription and prescription medications.

What to expect during a WBC count

The healthcare provider will draw your blood sample for the WBC count. The blood sample collection will be from a vein on the back of your hand or arm. This process takes only a few minutes and causes only minor discomfort.

For the blood sample collection, the healthcare professional will clean the site to kill any germ, then tie an elastic band on the upper part of your arm. The elastic bands help blood fill your vein, making the blow draw easier.

The professional will insert the needle into our hand or arm to collect the blood into an attached tube. After collecting the blood, your provider will remove the elastic band around your arm and remove the needle, then apply gauze or bandage to the site to prevent bleeding.

Drawing blood from infants and young children follows a different procedure, including puncturing the skin with a lancet and then using a test strip or a small vial for blood collection.

Complications from a WBC count procedure

A blood sample collection is a simple procedure which rarely causes complications. However, drawing blood from people with small veins may be difficult. The healthcare professional may not easily locate the vein at first. The professional may have to move the needle around after insertion to draw blood. This may result in a stinging sensation or sharp pain.

Rare complications from a blood test include:

If you need a WBC count, our healthcare professionals draw your blood for the test. You can call us on 02071830244 to book an appointment for your WBC count, including other blood tests.