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Cerebrospinal fluid hair cell count (substance concentration)

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

This test measures the number of hair cells (microglia) in your cerebrospinal fluid (CSF). Hair cells are a type of immune cell found in the brain and spinal cord.

Quick summary

["Hair cells in CSF can help diagnose or monitor certain neurological conditions."]

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

Key facts at a glance

LOINC
50842-4
Short code
Cr Hair-sCnt
Synonyms
Cr Hair-sCnt
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Might This Test Be Ordered?

Your healthcare provider may order this test if they suspect conditions like multiple sclerosis, meningitis, or other inflammatory or infectious processes affecting the central nervous system. It can also be used to assess the effectiveness of treatments for these conditions.

What Does the Test Involve?

A small amount of cerebrospinal fluid is collected through a procedure called a lumbar puncture (spinal tap). The fluid is then examined under a microscope to count the hair cells present.

What to Expect Before the Test

You may be asked to fast for a few hours before the test, depending on your specific situation. Inform your healthcare provider about any medications you’re taking, as some may affect the procedure or results.

What to Expect During the Test

You’ll lie on your side with your back bent at the waist. A needle is inserted into your lower back to collect the CSF. You may feel pressure or a slight pinch, but the procedure is usually quick and painless.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CSF Hair Cell Count

Frequently asked questions

What does an abnormal hair cell count mean?
An abnormal count could signal an underlying neurological issue, such as inflammation, infection, or a condition affecting the brain or spinal cord. Your healthcare provider will discuss the results with you and may recommend further testing or treatment.
How long does it take to get results?
Results from this test are usually available within a few days. The timing can vary depending on the lab and your healthcare provider’s workflow.
Can I drink or eat before this test?
Follow your healthcare provider’s instructions regarding food and fluids before the test. Typically, you may need to fast for a few hours, but always confirm with them to avoid any delays or complications.
  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