White Blood Cell Count WBC Count

Also known as: WBC Count, Leukocyte Count, White Count

Why do you need to get tested?

This test is ordered by the doctor to screen for and/or diagnose conditions that can impact the number of white blood cells or affect white blood cells adversely. The test is also used to monitor treatments of disorders or monitor therapy that can impact white blood cells.

When do you need to get tested?

The test can be ordered as part of a complete blood cell count, a routine health check-up, when the patient has signs and symptoms of conditions that can have an impact on white blood cells, or if the patient is receiving treatment that is known to impact white blood cells.

Which kind of sample is required?

This test involves a blood sample being drawn from a vein in the arm using a syringe. Sometimes, a fingerstick is used for adults and children while a heel stick is used for newborn babies.

Do you need to prepare for the test?

There is no preparation needed for the test.

What is being tested in White Blood Cell Count?

This test measures the number of leukocytes, also known as white blood cells, in the blood. These cells are found in the blood, the lymphatic system, tissues and play a pivotal role in the defense system of the body. They help in protecting against infections and play a role in inflammation and allergic reactions. There are five types of white blood cells, each of which has a different function. When there is an infection or inflammatory process somewhere in the body, the bone marrow releases white blood cells into the blood and they move into the site of infection or inflammation. When the condition resolves, the production of white blood cells by the bone marrow subsides and the number of white blood cells drops to normal levels once more. Conditions like cancer and immune disorders also impact the number of white blood cells, increasing or decreasing them. Higher levels of leukocytes in the bloodstream indicate an infection. Leukocytes may also be found in a urinalysis. A high level of white blood cells in the urine, suggests that the patient has an infection. Here, the body is trying to fight off an infection in the urinary tract, such as the bladder or the urethra.

How is the test used?

The test may be used as part of a complete blood count to:

Help screen for various kinds of diseases and conditions
Aid in the diagnosis of an infection or inflammatory process
Help diagnose other diseases which increase or decrease the number of white blood cells, such as allergies, leukemia, or immune disorders, to name a few.
Monitor the progression of various conditions
Assess and evaluate how the body responds to various treatments
Evaluate bone marrow function; some treatments, such as radiation and chemotherapy, have a known impact on white blood cells and are thus monitored using this test
Help detect a disease or a condition that affects white blood cells

The test cannot always determine the reason behind diseases and conditions. Thus, it is used in conjunction with other tests like the white blood cell differential, blood smear review, or bone marrow examination, which reveals abnormal or immature white blood cells.

When is the test ordered?

The test is ordered when the patient has general signs and symptoms of infection or inflammation. These include:

Fever and chills
Body aches and pain
Headaches

It may also be ordered when the patient displays symptoms of a urinary tract infection. The symptoms include:

Frequent urge to urinate
Burning sensation when urinating
Cloudy or pink-tinged urine
Strong-smelling urine
Pelvic pain, especially in women

The test may also be performed when the patient has signs or symptoms related to blood disorders, immune deficiency, and autoimmune disorders. Also, the test may commonly be ordered when the patient has an infection, blood, or autoimmune disorder which impacts the number and types of white blood cells.

What does the test result mean?

The test is often interpreted in light of other factors tested in a complete blood count. A high number of white blood cells occurs because of:

Infections caused by bacteria and some viruses
Inflammation or inflammatory conditions such as rheumatoid arthritis, vasculitis or inflammatory bowel disease
Leukemia or myeloproliferative neoplasms
Conditions that result in tissue death (necrosis) such as trauma, burns, surgery, or heart attack
Allergic responses (e.g., allergies, asthma)

Low white blood cell count occurs in:

Bone marrow damage (e.g., exposure to toxins, chemotherapy, radiation therapy, drugs)
Bone marrow disorders: the bone marrow fails to produce adequate WBCs (e.g., myelodysplastic syndrome, vitamin B12, or folate deficiency)
Lymphoma or other cancer that has spread (metastasized) to the bone marrow
Autoimmune disorders: the body attacks and destroys its own WBCs (e.g., lupus)
Dietary deficiencies (e.g., vitamin B12 deficiency)
Overwhelming infections (e.g., sepsis
Diseases of the immune system, such as HIV, which destroy T lymphocytes

Related Tests: Complete Blood Count (CBC blood test), Blood Smear, White Blood Cell Differential, Body Fluid Testing, Bone Marrow Aspiration, and Biopsy, Immunophenotyping by Flow Cytometry, Chromosome Analysis (Karyotyping)

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