Test Catalog

Test Id : PSYCF

Psychosine, Spinal Fluid

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

Aids in the biochemical diagnosis of Krabbe disease using cerebrospinal fluid specimens

 

Follow-up of individuals affected with Krabbe disease

 

Follow-up testing after an abnormal newborn screening result for Krabbe disease

 

Monitoring of individuals at risk to develop late onset Krabbe disease

 

Monitoring of individuals with Krabbe disease after hematopoietic stem cell transplantation

Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request

This test is used as a biomarker of Krabbe disease for individuals with reduced galactocerebrosidase (GALC) activity and for monitoring of patients with Krabbe disease and Saposin A cofactor deficiency. In cerebrospinal fluid (CSF), psychosine is typically ordered when CSF is collected primarily to determine protein content in a patient at risk of or monitored for the development of signs of Krabbe disease.

Highlights

Krabbe disease (globoid cell leukodystrophy) is an autosomal recessive lysosomal disorder caused by deficient activity of the enzyme galactocerebrosidase (GALC).

 

Krabbe disease is clinically variable and infantile-onset Krabbe disease is the most severe variant with rapid neurological regression resulting in early death.

 

Elevations in psychosine support a diagnosis of Krabbe disease; therefore, psychosine quantitation is a useful biomarker in determining if an individual has active disease. In addition, psychosine may be a valuable biomarker to monitor disease progression, or treatment response.

 

Psychosine may also be elevated in Saposin A cofactor deficiency, which results in a similar clinical phenotype to Krabbe disease, but patients typically have normal GALC activity in vitro.

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

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

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

Yes

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

Psychosine, CSF

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

Galactopsychosine

Galactosylphingosine

Krabbe disease

Psychosine

Specimen Type
Describes the specimen type validated for testing

CSF

Shipping Instructions

Send on dry ice. Avoid freeze thaw cycles.

Necessary Information

1. Patient’s age is required.

2. Date of hematopoietic stem cell transplantation (HSCT), if performed.

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

Collection Container/Tube: Sterile vial.

Specimen Volume: 0.150 mL

Collection Instructions: Do not aliquot.

Forms

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

0.100 mL

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

Gross hemolysis Reject

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

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

Aids in the biochemical diagnosis of Krabbe disease using cerebrospinal fluid specimens

 

Follow-up of individuals affected with Krabbe disease

 

Follow-up testing after an abnormal newborn screening result for Krabbe disease

 

Monitoring of individuals at risk to develop late onset Krabbe disease

 

Monitoring of individuals with Krabbe disease after hematopoietic stem cell transplantation

Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request

This test is used as a biomarker of Krabbe disease for individuals with reduced galactocerebrosidase (GALC) activity and for monitoring of patients with Krabbe disease and Saposin A cofactor deficiency. In cerebrospinal fluid (CSF), psychosine is typically ordered when CSF is collected primarily to determine protein content in a patient at risk of or monitored for the development of signs of Krabbe disease.

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

Krabbe disease (globoid cell leukodystrophy) is an autosomal recessive lysosomal disorder caused by deficient activity of the enzyme galactocerebrosidase (GALC). GALC facilitates the lysosomal degradation of psychosine (galactosylsphingosine) and 3 other substrates (galactosylceramide, lactosylceramide, and lactosylsphingosine). Krabbe disease is caused by mutations in the GALC gene, and it has an estimated frequency of 1 in 250,000 births.

Eighty-five percent to 90% of patients present before the first year of life with central nervous system impairment including increasing irritability, developmental delay, and sensitivity to stimuli. Rapid neurodegeneration including white matter disease follows, with death usually occurring by 2 years of age. Ten percent to 15% of individuals have later onset variants of the disease that are characterized by ataxia, vision loss, weakness, and psychomotor regression, presenting anytime from 6 months to the seventh decade of life. The clinical course of Krabbe disease can be variable, even within the same family.

 

Newborn screening for Krabbe disease has been implemented in some states. The early (presymptomatic) identification and subsequent testing of infants at risk for Krabbe disease may be helpful in reducing the morbidity and mortality associated with this disease. While treatment is mostly supportive, hematopoietic stem cell transplantation has shown some success if performed prior to onset of neurologic damage.

 

Psychosine (PSY) is a neurotoxin at elevated concentrations. Importantly, it is 1 of 4 substrates degraded by GALC. It has been shown to be elevated in patients with active Krabbe disease or with Saposin A cofactor deficiency, and therefore, may be a useful biomarker for the presence of disease or disease progression.

Reduced or absent GALC in leukocytes (CBGC / Galactocerebrosidase, Leukocytes) or dried blood spots (PLSD / Lysosomal and Peroxisomal Storage Disorders Screen, Blood Spot) along with psychosine analysis can indicate a diagnosis of Krabbe disease. Molecular sequencing of the GALC gene (KRABZ / Krabbe Disease, Full Gene Analysis and Large [30 kb] Deletion, PCR) allows for detection of the disease-causing mutations in affected patients and carrier detection in family members.

 

Individuals with a disease phenotype similar to Krabbe disease may have Saposin A cofactor deficiency. Saposin A cofactor deficiency also results in elevated psychosine levels. Testing for this condition via molecular analysis of PSAP is useful in those with elevated psychosine and normal to reduced GALC activity with normal molecular genetic GALC analysis.

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.

Normal < 0.04 nmol/L

Interpretation
Provides information to assist in interpretation of the test results

An elevation of psychosine is indicative of Krabbe disease or Saposin A cofactor deficiency.

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

Asymptomatic patients with later onset Krabbe disease may have a normal psychosine concentration in cerebrospinal fluid (CSF).

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

1. Kwon JM, Matern D, Kurtzberg J, et al: Consensus guidelines for newborn screening, diagnosis and treatment of infantile Krabbe disease. Orphanet J Rare Dis. 2018;13(1):30 doi: 10.1186/s13023-018-0766-x

2. Orsini JJ, Escolar ML, Wasserstein MP, et al: Krabbe Disease. In GeneReviews Edited by: MP Adam, HH Ardinger, RA Pagon: University of Washington, Seattle. 1993-2019. 2000 Jun 19 [Updated 2018 Oct 11]. Accessed May 2019. Available at: www.ncbi.nlm.nih.gov/books/NBK1238/

3. Turgeon CT, Orsini JJ, Sanders KA, et al: Measurement of psychosine in dried blood spots - a possible improvement to newborn screening programs for Krabbe disease. J Inherit Metab Dis. 2015;38: 923–929

4. Wenger DA, Escolar ML, Luzi P, Rafi MA: Krabbe disease (Globoid Cell Leukodystrophy). In The Online Metabolic and Molecular Bases of Inherited Disease. Edited by D Valle, AL BeaudetL, B Vogelstein, KW Kinzler, SE Antonarakis, A Ballabio, K Gibson, G Mitchell. New York, NY: McGraw-Hill; 2014 Accessed March 20, 2019. Available at: http://ommbid.mhmedical.com/content.aspx?bookid=971&sectionid=62644214

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

Psychosine is extracted from CSF and quantified using an isotopically labeled internal standard by LC-MS/MS.(Unpublished Mayo method)

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

No

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.

Tuesday, Thursday

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.

3 to 7 days

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

Indefinitely

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

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

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 was developed, and its performance characteristics 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.

82542

LOINC® Information

Test Id Test Order Name Order LOINC Value
PSYCF Psychosine, CSF 93686-4
Result Id Test Result Name Result LOINC Value
Result LOINC Value Tooltip
606150 Interpretation (PSYCF) 59462-2
606146 Psychosine, CSF 93686-4
605158 Reviewed By 18771-6

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