PSY - Overview: Psychosine, Blood Spot

Test Catalog

Test Name

Test ID: PSY    
Psychosine, Blood Spot

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

Aids in the biochemical diagnosis of Krabbe disease


Follow-up of individuals affected with Krabbe disease


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

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 second-tier assay for newborn screens with reduced GALC (galactocerebrosidase) activity and to diagnose and monitor patients with Krabbe disease.


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


Although Krabbe disease is clinically variable, the most common and severe form of the disorder is early infantile onset that presents with rapid neurological regression and results 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, to monitor disease progression, or treatment response.

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

See Newborn Screen Follow-up for Infantile Krabbe Disease in Special Instructions.


For more information, see Newborn Screening Act Sheet Krabbe Disease: Decreased Galactocerebrosidase in Special Instructions.

Special Instructions and Forms Library of PDFs including pertinent information and consent forms, specimen collection and preparation information, test algorithms, and other information pertinent to test

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

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

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


Reporting Name A shorter or abbreviated version of the Published Name for a test; an abbreviated test name

Psychosine, BS

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

Krabbe disease