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Background/Purpose

Leukocytes or white blood cells (WBCs) are immune cells that fight infection, neoplasms and other inflammatory conditions, and mediate allergic responses. There are five types of WBCs normally present in the circulation that are all derived from a similar stem cell in the bone marrow. The five type of WBCs are divided into two groups based on the presence or absence of granules in the cytoplasm. The granulocytes include the neutrophils, basophils and eosinophils. The non-granulocytes include the lymphocytes and the monocytes. The neutrophils fight infection by ingesting and digesting bacteria. Eosinophils and basophils respond to allergic reactions and are capable of ingesting antigen-antibody complexes. Monocytes phagocytose bacteria and release interferon to stimulate the immune system. Lymphocytes are divided into T-cells and B-cells. T-cell immunity is cellular and involves the activation of phagocytes and B-cell immunity uses antibodies to fight infection. Both elevated and low leukocyte counts can be markers of infection and malignancy, and low leukocyte counts are associated with a variety of primary and secondary immunodeficiencies, depending on the WBC type(s) that are out of range. (Mosby's manual of diagnostic and laboratory tests, Kathleen Deska Pagana; Timothy James Pagana, Elsevier St. Louis, Mo ©2010)

Procedure

This test is often performed as part of a larger panel of tests including the Complete Blood Count.
A blood draw is made from the patient.
Specimen: Whole blood
Volume: Fill tube to capacity.
Minimum Volume: 0.5 mL (500 μL for pediatric microtainer capillary tubes; fill tube to capacity)
Container: Lavender-top (EDTA) tube
Collection: Invert tube 8 to 10 times immediately after tube is filled at the time of collection.
Storage Instructions: Maintain specimen at room temperature.
Performed: Axially

Dialog

WBC Count

Criteria

• Normal number of WBCs
• Normal type of WBCs

Measurement

x10E3 uL

LOINC Code

6690-2

Scale/Grading

selection range; grade - LOINC ID
Option - Value option selection range; grade - LOINC IDNormal between 3.4-10.8 x10E3 uL ; Pass - High > 10.8 x10E3 uL ; Fail - Low < 3.4 x10E3 uL ; Fail -