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Test Code AFP, CSF Alpha-Fetoprotein (AFP), Spinal Fluid

Reporting Name

Alpha-Fetoprotein, CSF

Useful For

An adjunct in the diagnosis of central nervous system (CNS) germinomas and meningeal carcinomatosis

 

Evaluating germ-cell tumors, including testicular cancer metastatic to the CNS in conjunction with beta-human chorionic gonadotropin measurement(1)

 

An adjunct in distinguishing between suprasellar dysgerminomas and craniopharyngiomas

 

A supplement to cerebrospinal fluid cytologic analysis


Specimen Required


Container/Tube: Sterile vial

Specimen Volume: 1 mL


Specimen Type

CSF

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
CSF Frozen (preferred) 7 days
  Refrigerated  7 days

Day(s) and Time(s) Performed

Monday through Friday; 5 a.m.-12 a.m., Saturday; 6 a.m.-6 p.m.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

Immunoenzymatic Assay

Method Description

The instrument used is a Beckman Coulter UniCel Dxl 800. The Access alpha-fetoprotein (AFP) immunoassay is a 2-site immunoenzymatic sandwich assay. A sample is added to a reaction vessel with mouse monoclonal anti-AFP alkaline phosphatase conjugate, and paramagnetic particles coated with a second mouse monoclonal anti-AFP antibody. The AFP in the sample binds to the immobilized monoclonal anti-AFP on the solid phase while, at the same time, the monoclonal anti-AFP-alkaline phosphatase conjugate reacts with different antigenic sites on the sample AFP. After incubation in a reaction vessel, materials bound to the solid phase are held in a magnetic field while unbound materials are washed away. Then a chemiluminescence substrate Lumi-Phos 530 is added to the reaction vessel and light generated by the reaction is measured with a luminometer. The light production is directly proportional to the amount of AFP in the sample. The amount of analyte in the sample is determined by means of a stored multipoint calibration curve. Because the protein matrix is less concentrated in cerebrospinal fluid, a "protein spike" is added to each specimen prior to analysis. A correction is made for the dilution effect prior to reporting.(Beckman Coulter package insert, Beckman Coulter, Brea, CA, 2015)

Reference Values

<1.5 ng/mL

Values for alpha-fetoprotein in cerebrospinal fluid have not been formally established for newborns and infants. The available literature indicates that by 2 months of age, levels comparable to adults should be reached.(Ann Clin Biochem 2005;42:24-29)

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

86316

LOINC Code Information

Test ID Test Order Name Order LOINC Value
AFPSF Alpha-Fetoprotein, CSF 1833-3

 

Result ID Test Result Name Result LOINC Value
AFSF Alpha-Fetoprotein, CSF 1833-3

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

NA

Icterus

NA

Other

NA