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Serum/Plasma Leukocyte Count (Absolute)

Published: August 9, 2026Updated: August 16, 2026

This test measures the number of white blood cells in your blood, which helps assess your immune system and detect infections or inflammation.

Quick summary

["A white blood cell count helps doctors monitor immune health and identify possible infections or conditions like leukemia."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
49068-0
Short code
SLEV IgG+IgM CSF-Imp
Synonyms
SLEV IgG+IgM CSF-Imp
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why This Test Matters

White blood cells are crucial for fighting infections and protecting your body from illness. This test helps track how well your immune system is functioning, especially if you have symptoms like frequent infections, fatigue, or unexplained fevers.

When You Might Need It

Your doctor may order this test if you have symptoms like frequent infections, unexplained weight loss, swollen lymph nodes, or if you’re undergoing treatment for conditions like cancer or autoimmune diseases.

What to Expect Before the Test

You’ll typically have a simple blood draw from a vein in your arm. No special preparation is usually needed, but let your doctor know about any medications or conditions that might affect results.

What the Results Mean

Results show the total number of white blood cells, broken down into different types (neutrophils, lymphocytes, etc.). Abnormally high or low counts can signal infections, inflammation, or other health issues.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Absolute White Blood Cell Count

Frequently asked questions

What causes a high white blood cell count?
High white blood cell counts can be caused by infections (like colds or pneumonia), inflammation, stress, or certain medical conditions. Chronic diseases, such as leukemia or autoimmune disorders, may also lead to elevated counts.
What causes a low white blood cell count?
Low white blood cell counts can result from infections, bone marrow disorders (like leukemia), certain medications, or immune system issues. Chronic illnesses or autoimmune conditions may also contribute.
Do lifestyle factors affect this test?
Yes, lifestyle factors like stress, diet, and sleep can influence white blood cell counts. Avoiding heavy exercise or smoking for a day before the test may help provide more accurate results.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy