Normal White Blood Cell (WBC) Count by Age

If you have had your blood tested, you may have seen the letters WBC among the results. This is your white blood cell (WBC) count.

The WBC count test is among several that can help your healthcare provider figure out if something is going on inside of your body. It is also used to monitor chronic health conditions and check your response to treatment.

This article discusses the WBC count test. It explains the different types of WBCs and what they do, and the normal WBC count by age.

white blood cell count ranges

Verywell/Nez Riaz

What Is a WBC Test?

A WBC count test is a blood test that assesses the percentage and types of white blood cells in your body.

White blood cells are a group of blood cells that fight infection and inflammation in the body. They also protect your body from damage due to toxins (like air pollution) and aid wound healing and tissue repair.

White blood cells are produced in the bone marrow and are an essential part of your immune system. Although they make up less than 1% of your total blood cells, they play a vital role in keeping you healthy.

A WBC count is a test that involves a simple blood draw. A healthcare practitioner will use a thin needle to collect blood from one of your veins, usually in your arm. You can generally get the test results back from the lab in a few days.

You don't need any special preparations for a WBC count test. You do not need to fast for it and it can be taken at any time of day.

What It Measures

A WBC count measures the total number of all white blood cells in your blood. There are five different types:

  • Neutrophils: These cells help fight bacteria and fungal infections. They usually make up 50% to 75% of all your white blood cells.
  • Lymphocytes: These cells help fight infections and produce immune proteins called antibodies. and attack tumors. Lymphocytes are found in both your blood and lymph tissues.
  • Monocytes: These cells help damaged or dead cells from the body. They also travel into tissues like the lungs and liver and become another type of cell that helps ease inflammation.
  • Eosinophils: These cells fight infections caused by parasites. They also respond to allergic reactions and inflammation.
  • Basophils: These cells release a chemical called histamine during an allergic response. This triggers symptoms like a runny nose or watery eyes.

If you see these five cell types on your results along with numeric values, it is because your healthcare provider ordered a WBC differential test. The "diff" test looks at each of the cell types to figure out what's going on in the body based on which values are either high or low. Doing so helps narrow the possible causes.

WBC counts are often part of a more comprehensive test called a complete blood cell (CBC) count. The CBC count looks not only at white blood cells but also at red blood cells (that transport oxygen throughout the body) and platelets (that are responsible for blood clotting).

A CBC count is a common test used to evaluate your overall health and detect a wide range of illnesses, including anemia, infections, and disease like leukemia.

Normal WBC Count by Age

No hard-and-fast number defines a "normal" WBC count—it differs from one person to the next. Factors like age, sex, race, smoking status, and others can influence what is normal for you.

WBCs are normally high at birth, steadily decrease through infancy, then gradually decline until adulthood. They are measured by the number of white blood cells per cubic millimeter of blood (cells/mm3).

Normal WBC counts by age are as follows:

  • Babies 0 to 2 weeks old: 9,000 to 30,000 cells/mm3
  • Babies 2 to 8 weeks old: 5,000 to 21,000 cells/mm3
  • Children 2 months to 6 years old: 5,000 to 19,000 cells/mm3
  • Children 6 to 18 years old: 4,800 to 10,800 cells/mm3
  • Adults: 4,500 to 11,00 cells/mm3

Normal results fall within these ranges. Results below these ranges are considered low, and anything above is considered high. However, what is normal can vary from one person to the next and can fluctuate throughout the day.

Normal WBC ranges can also be different from lab to lab. It is possible to have a normal WBC at one lab and find that you have a low or high WBC count at another. (This is why people who require ongoing blood tests are advised to use the same lab provider for all tests.)

What Is a Good WBC Level for a Woman?

The normal WBC count range for women is typically wider than that of men. For women, a normal WBC can vary from 4,500 to 11,000 cells/mm3. The normal range for men is between 5,000 and 10,000 cells/mm3.

What Does a High WBC Mean?

The WBC count isn't specific enough to diagnose any particular disease. Abnormal values are simply an indication that something may be wrong and what the possible causes may be.

If your WBC count is high, you have what is called leukocytosis. Some of the possible causes of leukocytosis include:

  • A bacterial, fungal, or parasitic infection
  • Inflammatory conditions
  • Burns
  • Corticosteroid use
  • Cigarette smoking
  • Pregnancy
  • Leukemia

What Does a Low WBC Mean?

If your WBC count is low, you are said to have leukopenia. On its own, it may not mean anything, though some of the possible causes of leukopenia include:

  • A blood or bone marrow disorder
  • Autoimmune disorders
  • Medication side effects
  • Chemotherapy or radiation therapy
  • A viral infection

Don't jump to worst-case scenarios if you see a "high" or "low" notation on your WBC count results. This test needs to be evaluated along with other blood test values and possibly more testing before your healthcare provider can narrow down the possible causes.

Medications Can Cause Abnormal WBC Counts

Many prescription and over-the-counter drugs can cause an abnormal WBC count. It is essential always to review your medication history with your healthcare provider.

Certain drugs can cause your WBC count to drop below the normal range of values. These include:

  • Antibiotics: Used to treat bacterial infections
  • Anticonvulsive drugs: Use to treat epilepsy and chronic pain
  • Chemotherapy: Used to treat cancer
  • Rituxan (rituximab): Used to treat autoimmune diseases and certain cancers

Some medicines can raise your WBC count. The more common include:

  • Albuterol: Used to treat asthma and other breathing problems
  • Beta-blockers: Used to treat high blood pressure
  • Corticosteroid drugs: Used to reduce inflammation
  • Epinephrine: Used to treat severe allergic reactions
  • Heparin: A blood thinner used to prevent blood clots
  • Lithium: Used to treat bipolar disorder

When to See Your Healthcare Provider

Symptoms that indicate your WBC count may be off include:

If you have these symptoms, your healthcare provider might order a WBC count test.

Further Testing

If your WBC count results come back as abnormal, your healthcare provider may order additional tests depending on your symptoms and medical history. These may include tests to see if you have:

  • An infection: Your healthcare provider may order a urinalysis, for example, if they think you have a urinary tract infection. If they believe you have a viral infection, it might contain a polymerase chain reaction (PCR) test to identify the suspected virus.
  • An inflammation problem: Your healthcare provider may order a C-reactive protein (CRP) test. CRP is a type of protein that increases if you have inflammation anywhere in the body.
  • An autoimmune disorder: Your healthcare provider may order an antinuclear antibody test (ANA) to detect if there are immune proteins, called autoantibodies, in your blood.
  • An allergy: Your healthcare provider may order a skin prick test or food allergy test to see what you may be allergic to.
  • Leukemia: Your healthcare provider may order a bone marrow biopsy or a microscopic evaluation of your blood using a tool called flow cytometry.

Summary

White blood cells help fight infection and inflammation. A white blood cell count test measures the number of white blood cells in a sample of blood. Many conditions, including infections, medications, inflammatory diseases, and blood or bone marrow disorders, can cause an abnormal WBC count.

The WBC count is measured in a reference range of values by the number of blood cells in a cubic millimeter of blood. Test results can vary by the lab you use and how it defines a low, normal, or high range.

Normal WBC counts vary by age. They start out high at birth and decline through childhood. The normal range also varies by sex and can fluctuate throughout the day.

A WBC count isn't specific enough to diagnose a particular disease or condition. Still, the test can provide valuable clues as to what is causing your symptoms.

15 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. King W, Toler K, Woodell-May J. Role of white blood cells in blood- and bone marrow-based autologous therapies. Biomed Res Int. 2018;2018:6510842. doi:10.1155/2018/6510842

  2. Kabat GC, Kim MY, Manson JE. White blood cell count and total and cause-specific mortality in the Women's Health Initiative. Am J Epidemiol. 2017 Jul 1;186(1):63–72. doi:10.1093/aje/kww226

  3. U.S. National Library of Medicine: MedlinePlus. White blood count (WBC).

  4. MedlinePlus. Complete blood count (CBC).

  5. University of Rochester Medical Center. White blood cell count.

  6. Coates S, Wang D, Pierscionek T, et al. Time- and race-specific haematological reference intervals for healthy volunteer trials: a retrospective analysis of pooled data from multiple phase I trials. Front Pharmacol. 2020 Mar 13;11:314. doi:10.3389/fphar.2020.00314

  7. Leukemia and Lymphoma Society. Understanding blood counts.

  8. Riley LK, Rupert J. Evaluation of patients with leukocytosis. Am Fam Physician. 2015;92(11):1004-11.

  9. Newburger PE, Dale DC. Evaluation and management of patients with isolated neutropenia. Semin Hematol. 2013;50(3):198-206. doi:10.1053/j.seminhematol.2013.06.010

  10. Moore DC. Drug-induced neutropenia: a focus on rituximab-induced late-onset neutropenia. P T. 2016 Dec;41(12):765–8.

  11. Van Seventer JM, Hochberg NS. Principles of infectious diseases: transmission, diagnosis, prevention, and controlInt Encycloped Pub Health. 2017;22-39. doi:10.1016/B978-0-12-803678-5.00516-6

  12. MedlinePlus. C-reactive protein (CRP) test.

  13. American College of Rheumatology. Antinuclear antibodies (ANA).

  14. American College of Allergy, Asthma & Immunology. Allergy testing,

  15. Davis AS, Viera AJ, Mead MD. Leukemia: an overview for primary careAm Fam Physician. 2014;89(9):731-8.

By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.