Test ID: GCT    
Galactosemia Reflex, Blood

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

Preferred test for diagnosis, carrier detection, and determination of genotype of galactose-1-phosphate uridyltransferase deficiency, the most common cause of galactosemia


Differentiating Duarte variant galactosemia from classic galactosemia


Confirming results of newborn screening programs

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

Preferred test to evaluate for possible diagnosis of galactosemia, routine carrier screening, and follow-up of abnormal newborn screening results. Comprehensive reflex test begins with quantitative galactose-1-phosphate uridyltransferase (GALT) enzyme analysis. If quantitative GALT enzyme value is less than 24.5 nmol/h/mg of hemoglobin, full gene sequencing of the GALT gene is performed.

Reflex Tests Lists tests that may or may not be performed, at an additional charge, depending on the result and interpretation of the initial tests.

Test IDReporting NameAvailable SeparatelyAlways Performed
GALZGalactosemia, Full Gene AnalysisYesNo

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

Testing begins with galactose-1-phosphate uridyltransferase (GALT) enzyme analysis. If GALT activity is greater than or equal to 24.5 nmol/h/mg of hemoglobin, testing is complete. No molecular test will be performed. If GALT activity is less than 24.5 nmol/h/mg of hemoglobin, galactosemia full gene sequencing will be performed at an additional charge.


For more information see Galactosemia Testing Algorithm

Special Instructions Library of PDFs including pertinent information and forms related to the test

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

Enzyme Reaction followed by 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.


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

Galactosemia Reflex, B

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

Galactosemia Carrier Testing
Galactosemia Confirmation Test
Galactosemia Gene Analysis
Galactose-1-Phosphate Uridyltransferase (GALT)
Galactosemia Enzyme
Galactosemia Diagnostic Testing