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Unidentified Analyte, Cerebrospinal Fluid — Substance Concentration

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

Measures the amount of a specified substance in cerebrospinal fluid. The analyte abbreviation in this code is ambiguous, so confirm the exact substance with the laboratory.

Quick summary

["This test measures a substance in cerebrospinal fluid, but the exact analyte should be confirmed with the laboratory."]

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

Key facts at a glance

LOINC
26587-6
Short code
AAA CSF-sCnc
Synonyms
AAA CSF-sCnc
Category
liver
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

What is this test?

This is a cerebrospinal fluid, or CSF, test that measures the concentration of a substance in the fluid surrounding the brain and spinal cord. The abbreviation used for the substance in this code is not unambiguous, so the laboratory report or ordering clinician should identify the exact analyte.

Why might I need this test?

CSF testing may be used to evaluate suspected infections, inflammation, bleeding, metabolic conditions, or other disorders affecting the brain and spinal cord. The reason for testing and the substance measured depend on the clinical situation.

How is the test performed?

Cerebrospinal fluid is usually collected through a lumbar puncture, also called a spinal tap. The laboratory then measures the concentration of the specified substance using an appropriate laboratory method.

How do I prepare for the test?

Follow the instructions provided by the clinician who ordered the test. A lumbar puncture may require you to lie on your side or curl forward, and the care team will explain the position, procedure, and any steps needed beforehand.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

A concentration outside the laboratory's expected range may reflect infection, inflammation, bleeding, metabolic changes, medication effects, or another condition affecting the nervous system. Results must be interpreted with symptoms, other laboratory findings, and the laboratory's reference information. The meaning of an abnormal result cannot be determined until the exact analyte is confirmed.

Short name

CSF substance concentration

Frequently asked questions

Is cerebrospinal fluid the same as blood?
No. Cerebrospinal fluid is a clear fluid that surrounds and protects the brain and spinal cord, whereas blood circulates throughout the body.
How is cerebrospinal fluid collected?
It is most often collected with a lumbar puncture, commonly called a spinal tap. A trained clinician performs the procedure in a controlled setting.
What does an abnormal result mean?
It may indicate a condition affecting the brain, spinal cord, or metabolism, but the significance depends on the substance measured and your overall clinical findings. Ask the ordering clinician to interpret the result in context.
  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