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Cerebrospinal Fluid White Blood Cell Count (with Differential Analysis)

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

This test measures the number of white blood cells in your cerebrospinal fluid (CSF), which is the fluid surrounding your brain and spinal cord. It helps assess for infections, inflammation, or other conditions affecting the central nervous system.

Quick summary

["A CSF white blood cell count can help diagnose or monitor conditions affecting your brain and spinal cord."]

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

Key facts at a glance

LOINC
46090-7
Short code
WBC tube4 # CSF
Synonyms
WBC tube4 # CSF
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Ref low
4.5
Ref high
11
Critical range
2 N/A – 30 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85004
SNOMED
900000000000003002
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why This Test Is Done

Doctors may order this test if you have symptoms like headaches, neck stiffness, fever, confusion, or neurological problems. It’s often done when there’s suspicion of meningitis, encephalitis, multiple sclerosis, or other inflammatory or infectious conditions in the central nervous system.

What to Expect Before the Test

You may receive a mild anesthetic to numb the area where the fluid is taken. A small needle is inserted into your lower back to collect a small amount of CSF. The procedure usually takes a few minutes and may cause mild discomfort.

What Happens During the Test

A healthcare provider will insert a needle into your back to collect CSF. The fluid is then sent to the lab for analysis, including counting white blood cells and examining their types.

What the Results Mean

Elevated white blood cells in CSF can indicate infections (like bacterial or viral meningitis), autoimmune diseases, or other inflammatory processes. Lower than expected counts may suggest normal findings or certain neurological disorders.

Reference range

Adult: 4.5-11.0 x 10^9/LN/A

Specimen: csf

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Elevated White Blood Cells in CSF

Short name

CSF WBC Count

Frequently asked questions

What causes elevated white blood cells in CSF?
Elevated white blood cells in CSF are most commonly due to infections (e.g., bacterial or viral meningitis), but they can also occur with autoimmune diseases (e.g., multiple sclerosis), brain tumors, or other inflammatory conditions. Your doctor will consider your symptoms and other test results to determine the cause.
How long does it take to get results?
Results from a CSF white blood cell count are typically available within a few hours to a day, depending on lab processing times. Your doctor will discuss the findings with you during a follow-up visit.
Can lifestyle changes affect this test?
No specific lifestyle changes are known to affect CSF white blood cell counts directly. However, if you have an infection or illness, it’s important to inform your doctor before the test, as it may impact 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