cells (WBCs), also called leukocytes, are an important part of the immune
system. These cells help fight infections by attacking bacteria, viruses, and
germs that invade the body. White blood cells originate in the bone marrow, but
circulate throughout the bloodstream. There are five major types of white blood
A WBC count is
a test that measures the number of white blood cells in your body. This test is
often included with a complete blood count (CBC). Your blood contains a
percentage of each type of white blood cell. Sometimes, however, your white
blood cell count can fall or rise out of the healthy range.
Purpose of a WBC count
It is normal
for doctors to order a complete blood count and check your WBC count during an
annual physical examination. Your doctor may recommend a WBC count if you complain
of persistent body aches, fever, chills, or headaches. A WBC count can detect
hidden infections within your body and alert doctors to undiagnosed medical
conditions, such as autoimmune diseases, immune deficiencies, and blood
disorders. This test also helps doctors monitor the effectiveness of
chemotherapy or radiation treatment in cancer patients.
What to expect from
a WBC count
provider or lab technician will draw blood to check your WBC count. This blood
sample is taken either from a vein in your arm or a vein on the back of your
hand. It only takes a couple of minutes to draw your blood and you may
experience minor discomfort. The healthcare provider will clean the needle site
to kill any germs and then tie an elastic band around the upper section of your
arm. This elastic band helps the blood fill your vein, making it easier for the
blood to be drawn.
healthcare provider slowly inserts a needle into your arm or hand, and collects
the blood in an attached tube. The provider then removes the elastic band from
around your arm and slowly removes the needle. The technician will apply gauze
to the needle site to stop the bleeding.
providers use a different technique when drawing blood from young children and
infants. With these patients, providers first puncture the skin with a lancet
(a pricking needle) and then use a test strip or a small vial to collect the
blood. Results are sent to a lab for review.
How to prepare for a
A WBC count
requires no specific preparation. You simply schedule an appointment with your
doctor or set up an appointment at a local medical laboratory. Certain
medications can interfere with your lab results and either lower or increase
your WBC count.
that may affect your test results include:
- chemotherapy medication
having your blood drawn, tell your doctor about all prescription and
nonprescription medications that you’re currently taking.
count test results
normal range is between 4,500 and 10,000 white blood cells per microliter (mcL).
Abnormal test results are classified by numbers that are higher or lower than
this range. It’s important to note that age can also affect the number of white
blood cells, with infants having a higher count than adults.
A low or
high WBC count can point to a blood disorder or other medical condition. To
identify the exact cause of a high or low WBC count, your doctor will take
several factors into consideration, such as your list of current medications,
symptoms, and medical history.
is the medical term used to describe a low WBC count. A low number can be
- autoimmune disorders
- bone marrow disorders/damage
- severe infections
- liver and spleen diseases
- radiation therapy
is the medical term used to describe a high WBC count. This can be triggered by:
- tumors in the bone marrow
- inflammatory conditions, such as
arthritis and bowel disease
- tissue damage
diagnosing the cause of a high or low WBC count and recommending a treatment
plan, doctors will periodically recheck your white blood cells. If your white
blood cell count remains high or low, this can indicate that your condition has
worsened. Your doctor may adjust your treatment. If your WBC count shows a
normal range, this usually indicates that the treatment is working.
blood drawn is a simple procedure, and complications are extremely rare. It can
be difficult to take blood from people with small veins. The lab technician may
be unable to locate a vein, or once the needle is inside the arm or hand, they
may have to move the needle around in order to draw blood. This can cause a
sharp pain or a stinging sensation. Rare complications include:
- infection at the needle site
- excessive bleeding
- lightheadedness or fainting
- bleeding underneath the skin (hematoma)