Test Catalog

Test Id : AFPSF

Alpha-Fetoprotein (AFP), Spinal Fluid

Useful For
Suggests clinical disorders or settings where the test may be helpful

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


Evaluating the presence of germ-cell tumors in the CNS, in conjunction with cerebrospinal fluid (CSF) beta-human chorionic gonadotropin measurement 


A supplement to CSF cytologic analysis

Method Name
A short description of the method used to perform the test

Immunoenzymatic Assay

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Alpha-Fetoprotein, CSF

Lists additional common names for a test, as an aid in searching

AFP (Alpha-Fetoprotein)

Alpha-Fetoprotein (AFP)

Fetoprotein, Alpha

Tumor Markers

Specimen Type
Describes the specimen type validated for testing


Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Container/Tube: Sterile vial

Preferred: Vial number 1

Acceptable: Any vial

Specimen Volume: 1 mL


Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.

0.5 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Gross icterus OK

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

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

Useful For
Suggests clinical disorders or settings where the test may be helpful

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


Evaluating the presence of germ-cell tumors in the CNS, in conjunction with cerebrospinal fluid (CSF) beta-human chorionic gonadotropin measurement 


A supplement to CSF cytologic analysis

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Alpha-fetoprotein (AFP) is an oncofetal glycoprotein, homologous with albumin, that is produced in early fetal life and in tumors arising from midline embryonic structures. AFP is synthesized in the yolk sac, liver, and gastrointestinal track of the fetus. In adults, the liver synthesizes AFP. AFP is not normally expressed in the central nervous system (CNS). AFP concentrations are increased in hepatomas and hepatocellular and colon carcinomas, as well as in germ-cell tumors arising from the ovaries and nonseminomatous germ-cell tumors of the testes and testicular teratocarcinomas.


Based on histologic components and differentiation, CNS germ cell tumors (GCT) are classified as either germinomatous or nongerminomatous germ cell tumors (NGGCT). NGGCT include embryonal carcinomas, yolk sac tumors, choriocarcinomas, and mixed tumors. Teratomas (including teratomas of testicular origin) are sometimes considered to be NGGCT. Germinomas comprise two-thirds of the CNS GCT, whereas NGGCT account for the other third. However, CNS GCT are rare, comprising only 1% to 2% of all primary CNS neoplasms. The presence of germinomas in the CNS, CNS involvement in metastatic cancer, and meningeal carcinomatosis may result in increased concentrations of AFP (and/or beta–human chorionic gonadotropin [hCG]) in cerebrospinal fluid (CSF). In some patients with primary or metastatic intracranial or intraspinal tumors containing trophoblasts, AFP secreted by trophoblasts can diffuse into the CSF. Following treatment, AFP elevation in CSF is a potential marker of tumor recurrence.


Increased concentrations of AFP in CSF are more indicative of sac tumors/yolk sac components in mixed GCT. High concentrations of hCG in CSF support the presence of choriocarcinomas/choriocarcinomatous components in mixed GCT. If a germ cell tumor is suspected, the measurement of CSF and serum AFP and hCG may be considered. The secretion of these tumor markers in the CSF is pathognomonic for NGGCT.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

<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)

Provides information to assist in interpretation of the test results

Alpha-fetoprotein (AFP) concentrations that exceed the upper end of normal are consistent with the presence of central nervous system (CNS) germinoma. The presence of germinomas in the CNS, CNS involvement in metastatic cancer, and meningeal carcinomatosis may result in increased cerebrospinal fluid AFP concentrations in approximately 20% of germinomas.

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Malignancy may occur without an elevation of alpha-fetoprotein in cerebrospinal fluid .Measurement of beta-human chorionic gonadotropin is recommended to improve sensitivity of detection.


Values obtained with different assay methods or kits may be different and cannot be used interchangeably.


Test results cannot be interpreted as absolute evidence for the presence or absence of malignant disease.


In rare cases, some individuals can develop antibodies to mouse or other animal antibodies (often referred to as human anti-mouse antibodies [HAMA] or heterophile antibodies), which may cause interference in some immunoassays. Caution should be used in interpretation of results and the laboratory should be alerted if the result does not correlate with the clinical presentation.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Jubran RF, Finlay J: Central nervous system germ cell tumors: controversies in diagnosis and treatment. Oncology. 2005 May;19(6):705-711

2. Seregni E, Massimino M, Nerini Molteni S, et al: Serum and cerebrospinal fluid human chorionic gonadotropin (hCG) and alpha-fetoprotein (AFP) in intracranial germ cell tumors. Int J Biol Markers. 2002 Apr-Jun;17(2):112-118

3. Hu M, Guan H, Lau CC,et al: An update on the clinical diagnostic value of beta-hCG and alpha FP for intracranial germ cell tumors. Eur J Med Res. 2016 Mar 12;21:10. doi: 10.1186/s40001-016-0204-2

4. Shi Q, Tian C, Pu C, Yu S, Huang X: CSF and serum AFP in patients without gestational or neoplastic AFP-secretion. Scand J Clin Lab Invest. 2012 Dec;72(8):619-22. doi: 10.3109/00365513.2012.725865

5. Coakley J, Kellie SJ: Interpretation of alpha-fetoprotein concentrations in cerebrospinal fluid of infants. Ann Clin Biochem. 2005 Jan;42:24-29

6. Shajani-Yi Z, Martin IW, Brunelle AA, Cervinski MA: Method validation of human chorionic gonadotropin and alpha-fetoprotein in cerebrospinal fluid: Aiding the diagnosis of intracranial germ cell tumors. J Appl Lab Med. 2017 Jul 1;2(1):65-75. doi: 10.1373/jalm.2016.022822

Method Description
Describes how the test is performed and provides a method-specific reference

The instrument used is a Beckman Coulter UniCel Dxl 800. The Access alpha-fetoprotein (AFP) immunoassay is a 2-site immunoenzymatic sandwich assay. The 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 the monoclonal anti-AFP-alkaline phosphatase conjugate reacts with different antigenic sites on the sample AFP. After incubation, materials bound to the solid phase are held in a magnetic field, while unbound materials are washed away. A chemiluminescence substrate is then 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. Prior to reporting, a correction is made for the dilution effect.(Package insert: Access AFP. Beckman Coulter; 04/2020)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Saturday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

1 to 3 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

12 months

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


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Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

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 US Food and Drug Administration.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
AFPSF Alpha-Fetoprotein, CSF 1833-3
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
AFSF Alpha-Fetoprotein, CSF 1833-3

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports