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WBC count

Leukocyte count; White blood cell count; White blood cell differential; WBC differential; Infection - WBC count; Cancer - WBC count

A WBC count is a blood test to measure the number of white blood cells (WBCs) in the blood. It is a part of a complete blood count (CBC).

WBCs are also called leukocytes. They help fight infections. There are five major types of white blood cells:

Five major types of white blood cells

The blood differential test measures the percentage of each type of white blood cell (WBC) that you have in your blood. It also reveals if there are...

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Basophils
Eosinophils
Eosinophils
An absolute eosinophil count is a blood test that measures the number of one type of white blood cells called eosinophils. Eosinophils become active...
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Lymphocytes (T cells, B cells, and Natural Killer cells)
Monocytes
Neutrophils

How the Test is Performed

A blood sample is needed.

Blood sample

Venipuncture is the collection of blood from a vein. It is most often done for laboratory testing.

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How to Prepare for the Test

Most of the time, you do not need to take special steps before this test. Tell your health care provider the medicines you are taking, including the ones without a prescription. Some drugs may change the test results.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or slight bruising. This soon goes away.

Why the Test is Performed

You will have this test to find out how many WBCs you have. Your provider may order this test to help diagnose conditions such as:

An infection
Allergic reaction
Inflammation
Blood cancer such as leukemia or lymphoma

Normal Results

The normal number of WBCs in the blood is 4,500 to 11,000 WBCs per microliter (4.5 to 11.0 × 10⁹/L).

Normal value ranges may vary slightly among different labs. Some labs use different measurements or may test different specimens. Talk to your provider about your test results.

What Abnormal Results Mean

LOW WBC COUNT

A low number of WBCs is called leukopenia. A count less than 4,500 cells per microliter (4.5 × 10⁹/L) is below normal.

Neutrophils are one type of WBC. They are important for fighting infections.

A lower than normal WBC count may be due to:

Bone marrow deficiency or failure (for example, due to infection, tumor, or abnormal scarring)
Cancer treating drugs, or other medicines (see list below)
Certain autoimmune disorders such as lupus (SLE)
SLE
Systemic lupus erythematosus (SLE) is an autoimmune disease. In this disease, the immune system of the body mistakenly attacks healthy tissue. It c...
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Disease of the liver or spleen
Radiation treatment for cancer
Certain viral illnesses, such as mononucleosis (mono)
Mononucleosis (mono)
Mononucleosis, or mono, is a viral infection that causes fever, sore throat, and swollen lymph glands, most often in the neck.
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Cancers that damage the bone marrow
Very severe bacterial infections
Severe emotional or physical stress (such as from an injury or surgery)
An ethnic/genetic trait (not uncommon in African Americans)

HIGH WBC COUNT

A higher than normal WBC count is called leukocytosis. It may be due to:

Certain drugs or medicines (see list below)
Cigarette smoking
After spleen removal surgery
Spleen removal surgery
Spleen removal is surgery to remove a diseased or damaged spleen. This surgery is called splenectomy. The spleen is in the upper part of the belly, ...
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Infections, most often those caused by bacteria
Inflammatory disease (such as rheumatoid arthritis or allergy)
Leukemia or Hodgkin disease
Leukemia
Leukemia is a type of blood cancer that begins in the bone marrow. Bone marrow is the soft tissue in the center of the bones, where blood cells are ...
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Hodgkin disease
Hodgkin lymphoma is a cancer of lymph tissue. Lymph tissue is found in the lymph nodes, spleen, liver, bone marrow, and other sites.
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Tissue damage (for example, burns)
Pregnancy

There may also be less common reasons for abnormal WBC counts.

Drugs that may lower your WBC count include:

Antibiotics
Anticonvulsants
Antithyroid drugs
Arsenicals
Captopril
Chemotherapy drugs
Chlorpromazine
Clozapine
Diuretics (water pills)
Histamine-2 blockers
Sulfonamides
Quinidine
Terbinafine
Ticlopidine

Drugs that may increase WBC counts include:

Beta adrenergic agonists (for example, albuterol)
Corticosteroids
Epinephrine
Granulocyte colony stimulating factor
Heparin
Lithium

Risks

There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another, and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight, but may include:

Excessive bleeding
Fainting or feeling lightheaded
Multiple punctures to locate veins
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)

Open References

References

Marcogliese AN, Hensch L. Resources for the hematologist: interpretive comments and selected reference values for neonatal, pediatric, and adult populations. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 159.

Vajpayee N, Graham SS, Bem S. Basic examination of blood and bone marrow. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 31.

Basophil (close-up) - illustration

Basophils are a specific type of white blood cell. These cells are readily stained with basic dyes (this is where the name comes from). Note the dark grains inside the cellular fluid (cytoplasm) of this basophil. Basophils make up only a small portion of the number of white blood cells but are important parts of the body's immune response. They release histamine and other chemicals that act on the blood vessels when the immune response is triggered.

Basophil (close-up)

illustration
Formed elements of blood - illustration

Blood transports oxygen and nutrients to body tissues and returns waste and carbon dioxide. Blood distributes nearly everything that is carried from one area in the body to another place within the body. For example, blood transports hormones from endocrine organs to their target organs and tissues. Blood helps maintain body temperature and normal pH levels in body tissues. The protective functions of blood include clot formation and the prevention of infection.

Formed elements of blood

illustration
White blood cell count - series

Presentation

<strong>White blood cell count - series</strong><p>The White Blood Cell (WBC) Count measures two components; the total number of WBC's (leukocytes) and the differential count. The differential count measures the percentages of each type of leukocyte present. WBC's are composed of granulocytes (neutrophils, eosinophils, and basophils) and non-granulocytes (lymphocytes and monocytes). White blood cells are a major component of the body's immune system. Indications for a WBC count include infectious and inflammatory diseases; leukemia and lymphoma; and bone marrow disorders.</p>

<strong>Procedure</strong><p>How the test is performed. Adult or child; Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding. Infant or young child; The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding. How to prepare for the test. Adults; No special preparation is necessary. Infants and children; The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age; infant test or procedure preparation (birth to 1 year) toddler test or procedure preparation (1 to 3 years) preschooler test or procedure preparation (3 to 6 years) schoolage test or procedure preparation (6 to 12 years) adolescent test or procedure preparation (12 to 18 years) How the test will feel. When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing. What the risks are. Risks associated with venipuncture are slight; excessive bleeding fainting or feeling lightheaded hematoma (blood accumulating under the skin) infection (a slight risk any time the skin is broken) multiple punctures to locate veins. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.</p>

<strong>Results</strong><p>Interfering factors. Acute emotional or physical stress can increase WBC counts. There are various types of white blood cells (WBCs) that normally appear in the blood; neutrophils (polymorphonuclear leukocytes; PMNs), band cells (slightly immature neutrophils), T-type lymphocytes (T cells), B-type lymphocytes (B cells), monocytes, eosinophils, and basophils. T and B-type lymphocytes are indistinguishable from each other in a normal slide preparation. Any infection or acute stress will result in an increased production of WBCs. This usually entails increased numbers of cells and an increase in the percentage of immature cells (mainly band zcells) in the blood. This change is referred to as a shift to the left. People who have had a splenectomy have a persistent mild elevation of WBCs. Drugs that may increase WBC counts include epinephrine, allopurinol, aspirin, chloroform, heparin, quinine, corticosteroids, and triamterene. Drugs that may decrease WBC counts include antibiotics, anticonvulsants, antihistamine, antithyroid drugs, arsenicals, barbiturates, chemotherapeutic agents, diuretics and sulfonamides. Normal values. WBC - 4,500 to 10,000 cells/mcl. (Note cells/mcl = cells per microliter). What abnormal results mean. Low numbers of WBCs (leukopenia) may indicate; bone marrow failure (for example, due to granuloma, tumor, fibrosis) presence of cytotoxic substance collagen-vascular diseases (such as lupus erythematosus) disease of the liver or spleen radiation High numbers of WBCs (leukocytosis) may indicate; infectious diseases inflammatory disease (such as rheumatoid arthritis or allergy) leukemia severe emotional or physical stress tissue damage (for example, burns).</p>

Basophil (close-up) - illustration

Basophils are a specific type of white blood cell. These cells are readily stained with basic dyes (this is where the name comes from). Note the dark grains inside the cellular fluid (cytoplasm) of this basophil. Basophils make up only a small portion of the number of white blood cells but are important parts of the body's immune response. They release histamine and other chemicals that act on the blood vessels when the immune response is triggered.

Basophil (close-up)

illustration
Formed elements of blood - illustration

Blood transports oxygen and nutrients to body tissues and returns waste and carbon dioxide. Blood distributes nearly everything that is carried from one area in the body to another place within the body. For example, blood transports hormones from endocrine organs to their target organs and tissues. Blood helps maintain body temperature and normal pH levels in body tissues. The protective functions of blood include clot formation and the prevention of infection.

Formed elements of blood

illustration
White blood cell count - series

Presentation

Tests for WBC count

Review Date: 2/2/2023

Reviewed By: Mark Levin, MD, Hematologist and Oncologist, Monsey, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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WBC count

Five major types of white blood cells

Eosinophils

How the Test is Performed

Blood sample

How to Prepare for the Test

How the Test will Feel

Why the Test is Performed

Normal Results

What Abnormal Results Mean

SLE

Mononucleosis (mono)

Spleen removal surgery

Leukemia

Hodgkin disease

Risks

References

Basophil (close-up) - illustration

Basophil (close-up)

Formed elements of blood - illustration

Formed elements of blood

White blood cell count - series