Leukocyte count

Also known as WBC, white blood cell count, white count, leucocyte count

cell count · no single molecular formula

LOINC 6690-2 code verified whole_blood 10*3/uL

What this substance is

A leukocyte is a cell, not a compound. The cell type is already recorded in the anatomy graph as CL:0000738; there is no molecular identity to give.

Reference ranges

Checking your own result against this range needs the running application; this is a static copy. Nothing you type anywhere in Empeiria is ever sent to a server.

This open edition shows a range only where a public-domain or openly licensed source states one, and none does for this marker yet. Compare your result with the range printed on your own lab report.

How it is measured

In practice

A health worker takes a small amount of blood from a vein in your arm with a needle. Babies give blood from a heel prick; older babies and children may give it from a fingertip or arm. You do not need any special preparation, but tell your provider what medicines you take.

Venous whole blood collected by venipuncture into an EDTA tube and run as part of a CBC; in newborns and young infants a heel-stick sample, and in older infants and children a fingertip or arm sample. No special preparation; some medicines may need to be stopped on the provider's advice.

Where: laboratory

Sources: Laboratory Procedure Manual, Complete Blood Count (NHANES 2007-2008), CDC National Center for Health Statistics; White Blood Count (WBC), MedlinePlus (U.S. National Library of Medicine) cited · not yet checked by a person

In the lab

flow cytometry

Fluorescence flow cytometry

The cells are made to file past a beam of light one at a time. How each one scatters the light and glows tells the machine what kind it is, and it counts them as they go.

Cells are hydrodynamically focused into single file through a flow cell; forward scatter, side scatter and fluorescence intensity separate the cell populations, which are counted.

What can throw it off

Clumped platelets or nucleated red cells can be counted as white cells, giving a falsely high count.

Why labs disagree: Normal counts genuinely differ between populations. Many people of sub-Saharan African or Arab ancestry carry the Duffy-null blood type and have an inherited lower neutrophil count that causes no symptoms. This was previously called benign ethnic neutropenia.

Sources: Analytical agreement and clinical interchangeability of routine complete blood count parameters between the Atellica HEMA 580 and Sysmex XN-1000 analyzers: a CLSI EP09c study. Front Med 2026 (PMC open access); Isolated Chronic Neutropenia in Adults: Causes, Diagnostic Work-Up, and Management - A Narrative Review. J Clin Med 2025 (PMC open access); Unreliable Automated Complete Blood Count Results: Causes, Recognition, and Resolution. Ann Lab Med 2022 (PMC open access) cited · not yet checked by a person

What it reports on

leukocyte structural component of
A white blood count is a count of the white blood cells (leukocytes) in the blood.
bone marrow synthesized by
White blood cells are made in the bone marrow.
immune system structural component of
White blood cells are part of the immune system and help the body fight infection.

Associated symptoms

Conditions this marker features in

When low

low Low white blood cell count · defining
Leukopenia is defined by the white cell count. MedlinePlus uses below 4,500 per microlitre; some studies use below 4,000. The two cutoffs differ, so check which one a lab uses.

Ordered as part of

cbc