C4U - Overview: C4 Acylcarnitine, Quantitative, Urine

Test Catalog

Test Name

Test ID: C4U    
C4 Acylcarnitine, Quantitative, Urine

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

Evaluation of patients with abnormal newborn screens showing elevations of iso-/butyrylcarnitine (C4) to aid in the differential diagnosis of short-chain acyl-CoA dehydrogenase and isobutyryl-CoA dehydrogenase deficiencies

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

Useful for differentiating the potential diagnoses of short chain acyl-CoA dehydrogenase (SCAD) versus isobutyryl-CoA dehydrogenase deficiency. The results are not informative when patient is receiving L-carnitine supplements.


Elevated iso-/butyrylcarnitine (C4) in plasma or newborn screening blood spots is due to either short chain acyl-CoA dehydrogenase (SCAD) deficiency or isobutyryl-CoA dehydrogenase (IBD) deficiency.


Urine C4 results can distinguish between SCAD deficiency, which results in normal C4 in urine, and IBD deficiency, which results in elevated C4 in urine.


If patient is receiving L-carnitine supplementation, the result of this urine acylcarnitine test will not be informative.

Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.

See Newborn Screening Follow-up for Isolated C4 Acylcarnitine Elevations (also applies to any plasma or serum C4 acylcarnitine elevation) in Special Instructions.

Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test

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

Flow Injection Analysis-Tandem Mass Spectrometry (FIA-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/abbreviated version of the Published Name for a test; an abbreviated test name

C4 Acylcarnitine, QN, U

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

Acylcarnitines, urine
IBDH (Isobutyryl-CoA Dehydrogenase) Deficiency
Isobutyryl-CoA Dehydrogenase (IBDH) Deficiency
Short Chain Acyl-CoA Dehydrogenase (SCAD) Deficiency