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Alpha-Fetoprotein, Cerebrospinal Fluid — Mass Concentration

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

Measures the concentration of alpha-fetoprotein in cerebrospinal fluid to help evaluate certain AFP-producing tumors involving the central nervous system.

Quick summary

["This specialized test looks for alpha-fetoprotein in spinal fluid, which may support evaluation of certain tumors but is not diagnostic by itself."]

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

Key facts at a glance

LOINC
1833-3
Short code
AFP CSF-mCnc
Synonyms
AFP CSF-mCnc
Category
liver
Sample
csf
Container
Sterile tube
Units
N/A
Ref low
0
Ref high
10
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82105
SNOMED
394971007
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

What is this test?

Alpha-fetoprotein (AFP) is a protein that can be made by certain tumors and by the developing liver and fetus. This test measures its mass concentration in cerebrospinal fluid, the fluid surrounding the brain and spinal cord.

Why might I need this test?

This uncommon test may be used when imaging or other findings raise concern for a tumor involving the central nervous system that produces AFP. It is generally interpreted together with imaging, symptoms, and other laboratory results.

How is the test performed?

A clinician collects cerebrospinal fluid through a lumbar puncture, also called a spinal tap. The laboratory then measures the amount of AFP in the sample.

How do I prepare for the test?

Fasting is usually not required, but follow the instructions provided for the lumbar puncture. Tell the clinician if you have a bleeding disorder, take blood thinners, or have another condition that could make the procedure riskier.

Reference range

Normal: <10 ng/mLN/A

Specimen: csf

No special preparation required. For PSA, avoid sexual activity for 24-48 hours before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

AFP, CSF

Frequently asked questions

Is this the same as a routine AFP blood test?
No. Routine AFP testing usually measures the protein in serum, while this test measures it in cerebrospinal fluid. CSF AFP testing is specialized and is not routinely performed for everyone.
Does an elevated result mean I have cancer?
No. An elevated result may increase concern for an AFP-producing tumor, but it can have other explanations and must be interpreted with the full clinical picture. Additional imaging or laboratory testing may be needed.
Does the test require sedation or a hospital stay?
A lumbar puncture is usually performed while the person lies on their side. Some settings use local anesthetic, and brief observation afterward is generally required, but the exact procedure and recovery depend on the clinical setting.
  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