LAB TEST

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 : Basophils Eosinophils Lymphocytes (T cells, B cells, and Natural Killer cells) Monocytes Neutrophils

How the Test is Performed

A blood sample is needed.

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 × 10 9 /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 × 10 9 /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…

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…

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,…

This is a summary. Read the full article at www.ucsfbenioffchildrens.org (reviewed 02/02/2023).

This page is general information and is not medical advice. It does not replace a registered doctor, and it is not a prescription or a recommendation to use any medicine or test. Prices are listed prices and may change. Always follow the advice of your doctor or pharmacist.